Embedded Processor and Microcontroller primer and FAQ

[Russ Hersch]

Archive-name: microcontroller-faq/primer
Posting-Frequency: monthly
Last-modified: January, 5, 1997

This article is a primer and general FAQ about embedded processors and
microcontrollers. Included is a collection of information sources.

The following topics are addressed:

0) Rantings and ravings (to make the FAQ zero-based)

1) ABOUT THIS FAQ
1.1) Who put this FAQ together?
1.2) How can I contribute to this FAQ?
1.3) What newsgroups will this FAQ be posted to?
1.4) May I distribute this FAQ or post it somewhere else?

2) MICROCONTROLLERS
2.1) What is a Microcontroller?
2.2) Applications
2.3) Flavors

3) THE MICROCONTROLLER MARKET
3.1) Shipments
3.2) Industrial applications
3.3) Deciding whose microcontroller to use
3.4) The players

4) MICROCONTROLLER FEATURES
4.1) Fabrication techniques
4.2) Architectural features
4.3) Advanced Memory options
4.4) Power Management and Low Voltage
4.5) I/O
4.6) Interrupts
4.7) Special microcontroller features

5) SOME POPULAR MICROCONTROLLERS

6) GETTING STARTED WITH MICROCONTROLLERS
6.1) Evaluation Kits/Boards
6.2) Easy chips to use
6.3) Software (cheap and easy)

7) MICROCONTROLLER PROGRAMMING LANGUAGES
7.1) Machine/Assembly language
7.2) Interpreters
7.3) Compilers
7.4) Fuzzy Logic and Neural Networks

8) DEVELOPMENT TOOLS
8.1) Simulators
8.2) Resident Debuggers
8.3) Emulators
8.4) Good Stereo System

9) FINDING OUT MORE ABOUT MICROCONTROLLERS
9.1) Books
9.2) Data and Reference Books
9.3) Periodicals
9.4) USENET newsgroups
9.5) Internet sources of information on specific microcontrollers

10) MICROCONTROLLER FREE SOFTWARE SOURCES
10.1) FTP sites
10.2) WEB pages
10.2) BBSs
10.3) Mailing lists

0) Rantings and ravings

Disclaimer: Just so it is understood, the "rantings and ravings" are
my rantings and ravings. My readers are refined and sophisticated
and would never rant or rave. I, on the other hand, sit in front of
the TV in torn underwear and drink beer out of the bottle.

Stefan Ward (of Diamond Chip) writes that for over two years his
company has used a micro programmable logic controller (MPLC-1000)
for internal projects. The MPLC-1000 has been designed with the
ST62T25 micro processor and enabled them to put working and stable
products on the market very quickly.

They programmed the ST62T25 chip as a token interpretor. Tokens are
read from a serial EEPROM and executed. Tokens vary from 4 to about
20 bits and are very compact and fast to execute. To simplify coding,
they designed their own BASIC compiler (of which they are very
proud). This is similar to, but much more advanced than the PIC Basic
stamp product.

They are now offering the BASIC chip (programmed ST62T25) at a very
good price for use by third party developers. They also sell a
developer's kit complete with a MPLC-1000 controller board. All
developer's information (i.e. circuit diagrams, BASIC compiler,
examples, etc) is available free of charge. See their web site for
more information: http://www.dchip.com

Stefan Ward, Diamond Chip
Tel +27 (0)12 803-6287
Fax +27 (0)12 803-4350
BBS +27 (0)12 803-5683
WWW: http://www.dchip.com

A bit ;-) of thanks to Magnus Danielson who pointed out my omission
of the 1 bit MC14500 chip. In his words, "This is an awesome chip
that everyone should know by heart... why? It's so weird compared to
most other chips... it is really worth reading up on the details. It
lives its life inside a 16 pin DIP and has 16 instructions."

Motorola was the manufacturer of this powerhouse, which is now out of
production. And no, there isn't a C compiler for it. Maybe Dave
Dunfield (hi Dave ;-) wouldn't mind adding this to his C compiler
suite.

Although the MC14500 is a bit bizarre (one bit's worth) and may be
somewhat limited, it does have a few noteworthy features:
- RISC processor with 16 instructions (well, what did you expect
from a 1 bit processor)
- no memory boundary (an infinite amount of memory)
- small package (16 pin)

Find a copy of the data sheet on this chip and give it a careful
going over. I'm sure you'll agree that this was an interesting chip
and I imagine was probably quite useful. Seems to me that the new
wave of scaled-down micros such as the Atmel 2051, MicroChip PIC, and
Philips 752 probably caused its demise.

A really great new book on the PIC has just come out - Easy PIC'n, A
Beginner's Guide to Using PIC 16/17 Microcontrollers from Square 1,
published by Square 1 Electronics. If you're a beginner at
microcontrollers, and even if you haven't programmed much on the PC,
but are interested in tinkering, this is THE book for you. Perfect
for the hobbyist or engineer for self study, or as a text for a
college engineering course in microcontrollers.

Based on the MPASM assembler (free from Micro Chip), the book is
written in an easy to understand tutorial format. Starting with just
the necessary details in order to get started, the reader is
introduced to more and more advanced concepts and techniques as the
book progresses. Complete with copious circuit diagrams and
illustrations, and plenty of sample code, the user is never left with
a feeling of not knowing of what's going on.

Examples of assembly language programs range from a simple one to
turn on LED's, to more complex ones for timing and for
event-counting. Writing programs is covered in-depth and the use
of flow charts as an aid to visualizing what a program does is
emphasized. The approach is hands-on with lots of examples, all of
which may be demonstrated using a very simple demo board project
described in the beginning of the book.

The objective with this book is to provide the core information
needed by the beginner to successfully program and use the PIC16/17
microcontrollers in his/her own projects, all with a minimum of
hassles.

Easy PIC'n, A Beginner's Guide to Using PIC 16/17 Microcontrollers
- ISBN 0-9654l62-0-8
- by David Benson, published by Square 1 Electronics
- squa...@zapcom.net
- 707/279-8881 Fax: 707/279-8883

After working your way through Easy PIC'n, you'll be a "just a PIC'n
and a Grin'n".

Take care of yourselves,

Uncle Russ

1) ABOUT THIS FAQ

1.1) Who put this FAQ together?

From time to time, general questions about microcontrollers and
embedded processors (from beginners to experienced designers) pop up
in the newsgroups. It seemed that a general primer/FAQ might be
useful.

Much of this document could be considered as a sort of a primer on
microcontrollers, with some material on embedded processors being
slowly added. For those of you with previous experience, sections 9
and 10 might be of special interest (especially for those of you
looking for that elusive "free COBOL compiler for the 1802").

1.2) How can I contribute to this list?

I please ask that if you have any suggestions or additions, or you
would like to correct any of the information contained herein, please
send me a note.
My Email address is: ru...@shani.net
My Smail address is:
Russ Hersch
HaVradim 11
Ginot Shomron
ISRAEL

Thanks to recent contributors:
David Benson (Square 1 Electronics)
Deborah Lamoree (Western Design Center)
Siegfried Ratzlaff
Gary Creager (Xicor)
Magnus Danielson
Stefan Ward (Diamond Chip)

Very special thanks to Robin L. Getz (National Semiconductor) who
probably could be considered an honorary co-author of this FAQ. :-)

Also, thanks to those who have posted questions and to those who have
posted answers. Thanks to "my new friends" who send suggestions and
encouragement, as well as the occasional question. Special thanks to
my mother-in-law, who thankfully will probably never read this
document ;-).

1.3) What newsgroups will this FAQ be posted to?

This FAQ will be posted to the following newsgroups:
comp.arch.embedded
comp.robotics.misc
comp.realtime
sci.electronics.design
alt.comp.hardware.homebuilt
comp.answers
sci.answers
alt.answers
news.answers

I will post once a month - on or about the 26th of each month.

1.4) May I distribute this FAQ or post it somewhere else?

I am putting no restrictions on the use of this FAQ except - It must
be distributed in its entirety with the copyright notice, and no
financial gain may be realized from it. After all, I have spent, and
continue to spend, a lot of time on this.

For this reason I have appended a copyright statement to the end of
this FAQ. I feel pretty silly doing this, but I just want to protect
myself. The copyright does not limit the use of this list for
noncommercial purposes. I hereby give my permission to one and all
to pass this list around and post it wherever you want - as long as
it is not for financial gain.

Thank you.

2) MICROCONTROLLERS AND EMBEDDED PROCESSORS

2.1) What is a Microcontroller?

A controller is used to control (makes sense!) some process or aspect
of the environment. A typical microcontroller application is the
monitoring of my house. As the temperature rises, the controller
causes the windows to open. If the temperature goes above a certain
threshold, the air conditioner is activated. If the system detects
my mother-in-law approaching, the doors are locked and the windows
barred. In addition, upon detecting that my computer is turned on,
the stereo turns on at a deafening volume (for more on this, see the
section on development tools).

At one time, controllers were built exclusively from logic
components, and were usually large, heavy boxes (before this, they
were even bigger, more complex analog monstrosities). Later on,
microprocessors were used and the entire controller could fit on a
small circuit board. This is still common - you can find many [good]
controllers powered by one of the many common microprocessors
(including Zilog Z80, Intel 8088, Motorola 6809, and others).

As the process of miniaturization continued, all of the components
needed for a controller were built right onto one chip. A one chip
computer, or microcontroller was born. A microcontroller is a highly
integrated chip which includes, on one chip, all or most of the parts
needed for a controller. The microcontroller could be called a
"one-chip solution". It typically includes:
CPU (central processing unit)
RAM (Random Access Memory)
EPROM/PROM/ROM (Erasable Programmable Read Only Memory)
I/O (input/output) - serial and parallel
timers
interrupt controller

By only including the features specific to the task (control), cost
is relatively low. A typical microcontroller has bit manipulation
instructions, easy and direct access to I/O (input/output), and quick
and efficient interrupt processing. Microcontrollers are a "one-chip
solution" which drastically reduces parts count and design costs.

2.2) What is an embedded controller?

Hah! Why not ask an easy question like "Did Adam have a navel?" or
"Did Eve?" <Can't say about Adam, but well, Eve probably did. She
would have looked pretty silly in a fig leaf, without a navel.>

Simply (and naively stated) an embedded controller is a controller
that is embedded in a greater system. A rigid definition is
difficult if not impossible to formulate, since the usual response is
"most embedded controllers are...". The problem here is "most". We
can't seem to shake that word from the definition. No matter how
clever you feel your definition is, some wiseguy will come along and
find an exception, or two, or 50.

You COULD say that an embedded controller is a controller (or
computer) that is embedded into some device for some purpose other
than to provide general purpose computing. Of course, someone will
eventually prove you wrong, but who cares?

A common example of a general purpose computer, would be a typical PC
clone. The x86 processor in this machine can't really be considered
an embedded controller, since the machine is typically used for
general purpose computing. However, what is general purpose
computing? Take this same PC clone, turn it into a multi-media
machine, and voila! You have an appliance - much on the order of a
microwave oven or television. Is the x86 processor now considered an
embedded controller Or, is the PC clone itself now considered an
embedded controller, controlling the multi-media peripherals? Hey -
I don't know about you, but I'm getting too old for this nonsense.

Is a microcontroller an embedded processor? Is an embedded processor
a microcontroller? What's the difference between an embedded
processor and a microcontroller? Well, today - not much. With the
continuing process of high scale integration continuing at a dizzying
pace, many standard architecture processors are turning up as
microcontrollers. A few such examples are the Motorola 68EC300,
Intel 386 EX, and the IBM PowerPC 403GB. These chips could be called
super-microcontrollers.

So, what's the difference between an embedded processor and a
microcontroller? I wouldn't touch that question with a ten foot
logic probe.

We might be safe by stating that an embedded processor controls
something (for example controlling a device such as a microwave oven,
car braking system, or a cruise missile). Is this always true?
Maybe. Maybe not. You know, it just doesn't end.

The main thing is not to get to hung up on precise definitions.
Black and white? Hell no, we've got grey scale, dithering,
diffusion, you name it! Same thing goes here with embedded
controllers, just go with the flow. It all depends on your point of
view.

Alright, if you really must insist, we'll take a stab at defining
what an embedded controller is - realize however that there will be
many exceptions. Embedded controllers adhere to a
philosophy similar to that of microcontrollers, high integration. By
including [many] features necessary for the task at hand, an embedded
controller (processor) can be a powerful yet cost effective solution.
However, where a microcontroller [almost by definition] is a computer
on a chip, an embedded controller might need external components
before it is considered a "computer." This is especially true
regarding RAM. Since including large amounts of RAM (megabytes) on a
processor is not really practical (due to cost and available silicon
real estate) and because many embedded controllers are real
powerhouses requiring large amounts of RAM, the RAM is often external
to the processor.

2.3) Applications

In addition to the above home monitoring system, embedded processors
and microcontrollers are frequently found in: appliances (microwave
oven, refrigerators, television and VCRs, stereos), computers and
computer equipment (laser printers, modems, disk drives), automobiles
(engine control, diagnostics, climate control), environmental control
(greenhouse, factory, home), instrumentation, aerospace, and
thousands of other uses. In many items, more than one processor can
be found.

Microcontrollers are typically used where processing power isn't so
important. Although some of you out there might find a microwave
oven controlled by a Unix system an attractive idea, controlling a
microwave oven is easily accomplished with the smallest of
microcontrollers. On the other hand, if you're putting together a
cruise missile to solve the problem of your neighbor's dog barking at
3 in the morning, you'll probably need to use processors with a bit
more computing power.

Embedded processors and microcontrollers are used extensively in
robotics. In this application, many specific tasks might be
distributed among a large number of controllers in one system.
Communications between each controller and a central, possibly more
powerful controller (or micro/mini/mainframe) would enable
information to be processed by the central computer, or to be passed
around to other controllers in the system.

A special application that microcontrollers are well suited for is
data logging. Stick one of these chips out in the middle of a corn
field or up in a ballon, and monitor and record environmental
parameters (temperature, humidity, rain, etc). Small size, low power
consumption, and flexibility make these devices ideal for unattended
data monitoring and recording.

2.4) Flavors

Embedded processors come in many flavors and varieties. Depending on
the power and features that are needed, you might choose a 4,
8, 16, or 32 bit microcontroller. Standard microprocessors (such as
the Motorola 68000 or National 32032) are frequently used as powerful
embedded controllers. In addition, specialized processors are
available which include features specific for communications,
keyboard handling, signal processing, video processing, and other
tasks.

3) THE MICROCONTROLLER MARKET

Thanks to Robin Getz of National Semiconductor for supplying much of
the material in this section.

3.1) Shipments

WorldWide Microcontroller Shipments (in millions of dollars)

'90 '91 '92 '93 '94 '95 '96 '97 '98 '99 '00
4-bit 1,393 1,597 1,596 1,698 1,761 1,826 1,849 1,881 1,856 1,816 1,757
8-bit 2,077 2,615 2,862 3,703 4,689 5,634 6,553 7,529 8,423 9,219 9,715
16-bit 192 303 340 484 810 1,170 1,628 2,191 2,969 3,678 4,405

WorldWide Microcontroller Shipments (in Millions)

'90 '91 '92 '93 '94 '95 '96 '97 '98 '99 '00
4-bit 778 906 979 1036 1063 1110 1100 1096 1064 1025 970
8-bit 588 753 843 1073 1449 1803 2123 2374 2556 2681 2700
16-bit 22 38 45 59 106 157 227 313 419 501 585

Source: WSTS & ICE - 1994

If you were wondering why you should bother learning about
microcontrollers - well, the tables above should fairly scream the
answer at you. Microcontrollers will be *BIG* business - we're
talking piles of cash - billions!

Notice that even the lowly 4-bit device is holding its own - what use
is a 16-bit part in a toaster oven? Also notice that the 8-bit
market just keeps growing, and will probably continue to grow. 8-bit
devices account for over half of the market, and will eventually grab
even more. Now do you understand why every silicon manufacturer is
really pushing their 8-bit microcontrollers?

3.2) Industrial applications

Average Semiconductor Content per Passenger Automobile (in Dollars)

'90 '91 '92 '93 '94 '95 '96 '97 '98 '99 '00
$ 595 634 712 905 1,068 1,237 1,339 1,410 1,574 1,852 2,126

Source: ICE - 1994

The automotive market is the most important single driving force in
the microcontroller market, especially at it's high end. Several
microcontroller families were developed specifically for automotive
applications and were subsequently modified to serve other embedded
applications.

The automotive market is demanding. Electronics must operate under
extreme temperatures and be able to withstand vibration, shock, and
EMI. The electronics must be reliable, because a failure that causes
an accident can (and does) result in multi-million dollar lawsuits.
Reliability standards are high - but because these electronics also
compete in the consumer market - they have a low price tag.

Automotive is not the only market that is growing. DataQuest says
that in the average North American's home there are 35
microcontrollers. By the year 2000 - that number will grow to 240.
Consumer electronics is a booming business.

3.3) Deciding whose microcontroller to use

When deciding which devices to implement in a design, there are lots
of things to consider besides who else is using these devices (and
how many are they using).
- Can I expect help when I am having problems?
- What development tools are available and how much do they cost?
- What sort of documentation is available (reference manuals,
application notes, books)?
- Can I work a deal by purchasing more devices at one manufacturer?
That is, purchasing not only the microcontroller, but also
peripherals (A/D, memory, voltage regulator, etc.) from one
company).
- Do they support OTPs, windowed devices, mask parts?

3.4) The players

MICROPROCESSORS
Rank Sales ($ millions)
1995 1994 Company 1995 1994
-----------------------------------------------
1 1 Intel $10,800 $8,036
2 3 AMD 881 992
3 2 Motorola 781 827
4 11 IBM 468 297
5 6 TI 219 202
6 4 Cyrix 210 240
7 5 Hitachi 188 66
8 7 NEC 100 82
9 8 LSI Logic 58 51
10 10 IDT 45 25

Source: In-Stat Inc.

MICROCONTROLLERS
Rank Sales ($ millions)
1995 1994 Company 1995 1994
-----------------------------------------------
1 1 Motorola $1,781 $1,511
2 2 NEC 1,421 1,208
3 4 Mitsibishi 945 708
4 3 Hitachi 899 782
5 5 Intel 835 605
6 6 TI 807 534
7 8 Philips 524 345
8 7 Matsushita 500 413
9 10 Lucent (AT&T) 492 275
10 9 Toshiba 400 328

Source: In-Stat Inc.

4) MICROCONTROLLER FEATURES

Thanks to Robin Getz of National Semiconductor who supplied some of
the material in this section.

4.1) Fabrication techniques

CMOS - Complementary Metal Oxide Semiconductor

This is the name of a common technique used to fabricate most (if
not all) of the newer microcontrollers. CMOS requires much less
power than older fabrication techniques, which permits battery
operation. CMOS chips also can be fully or near fully static,
which means that the clock can be slowed up (or even stopped)
putting the chip in sleep mode. CMOS has a much higher immunity
to noise (power fluctuations or spikes) than the older fabrication
techniques.

PMP - Post Metal Programming (National Semiconductor)

PMP is a high-energy implantation process that allows
microcontroller ROM to be programmed AFTER final metalization.
Usually ROM is implemented in the second layer die, with nine or
ten other layers then added on top. That means the ROM pattern
must be specified early in the production process, and completed
prototypes devices won't be available typically for six to eight
weeks. With PMP, however, dies can be fully manufactured through
metalization and electrical tests (only the passivation layers
need to be added), and held in inventory. This means that ROM can
be programmed late in production cycle, making prototypes
available in only two weeks.

4.2) Architectural features

Von-Neuman Architecure

Microcontrollers based on the Von-Neuman architecture have a
single "data" bus that is used to fetch both instructions and
data. Program instructions and data are stored in a common main
memory. When such a controller addresses main memory, it first
fetches an instruction, and then it fetches the data to support
the instruction. The two separate fetches slows up the
controller's operation.

Harvard Architecture

Microcontrollers based on the Harvard Architecture have separate
data bus and an instruction bus. This allows execution to occur
in parallel. As an instruction is being "pre-fetched", the
current instruction is executing on the data bus. Once the
current instruction is complete, the next instruction is ready to
go. This pre-fetch theoretically allows for much faster execution
than a Von-Neuman architecture, but there is some added silicon
complexity.

CISC

Almost all of today's microcontrollers are based on the CISC
(Complex Instruction Set Computer) concept. The typical CISC
microcontroller has well over 80 instructions, many of them very
powerful and very specialized for specific control tasks. It is
quite common for the instructions to all behave quite differently.
Some might only operate on certain address spaces or registers,
and others might only recognize certain addressing modes.

The advantages of the CISC architecture is that many of the
instructions are macro-like, allowing the programmer to use one
instruction in place of many simpler instructions.

RISC

The industry trend for microprocessor design is for Reduced
Instruction Set Computers (RISC) designs. This is beginning to
spill over into the microntroller market. By implementing fewer
instructions, the chip designed is able to dedicate some of the
precious silicon real-estate for performance enhancing features.
The benefits of RISC design simplicity are a smaller chip, smaller
pin count, and very low power consumption.

Among some of the typical features of a RISC processor:
- Harvard architecture (separate buses for instructions and
data) allows simultaneous access of program and data, and
overlapping of some operations for increased processing
performance
- Instruction pipelining increases execution speed
- Orthogonal (symmetrical) instruction set for programming
simplicity; allows each instruction to operate on any
register or use any addressing mode; instructions have no
special combinations, exceptions, restrictions, or side
effects

SISC

Actually, a microcontroller is by definition a Reduced Instruction
Set Computer (at least in my opinion). It could really be called
a Specific Instruction Set Computer (SISC). The [original] idea
behind the microcontroller was to limit the capabilities of the
CPU itself, allowing a complete computer (memory, I/O, interrupts,
etc) to fit on the available real estate. At the expense of the
more general purpose instructions that make the standard
microprocessors (8088, 68000, 32032) so easy to use, the
instruction set was designed for the specific purpose of control
(powerful bit manipulation, easy and efficient I/O, and so on).

Microcontrollers now come with a mind boggling array of features
that aid the control engineer - watchdog timers, sleep/wakeup
modes, power management, powerful I/O channels, and so on. By
keeping the instruction set specific (and reduced), and thus
saving valuable real estate, more and more of these features can
be added, while maintaining the economy of the microcontroller.

4.3) Advanced Memory options

EEPROM - Electrically Erasable Programmable Read Only Memory

Many microcontrollers have limited amounts of EEPROM on the chip.
EEPROM seems more suited (becuase of its economics) for small
amounts of memory that hold a limited number of parameters that
may have to be changed from time to time. This type of memory is
relatively slow, and the number of erase/write cycles allowed in
its lifetime is limited.

FLASH (EPROM)

Flash provides a better solution than regular EEPROM when there is
a requirement for large amounts of non-volatile program memory.
It is both faster and permits more erase/write cycles than EEPROM.

Battery backed-up static RAM

Battery backed-up static RAM is useful when a large non-volatile
program and DATA space is required. A major advantage of static
RAM is that it is much faster than other types of non-volatile
memory so it is well suited for high performance application.
There also are no limits as to the number of times that it may be
written to so it is perfect for applications that keep and
manipulate large amounts of data locally.

Field programming/reprogramming

Using nonvolatile memory as a place to store program memory allows
the device to be reprogrammed in the field without removing the
microcontroller from the system that it controls. One such
application is in automotive engine controllers. Reprogrammable
non-volatile program memory on the engine's microcontroller allows
the engine controller program to be modified during routine
service to incorporate the latest features or to compensate for
such factors as engine aging and changing emissions control laws
(or even to fix bugs!!). Reprogramming of the microcontroller
could become a standard part the routine engine tune-up.

Almost every application could benefit from this type of program
memory - If a modem's hardware supported it, you could remotely
upgrade your modem from Vfast to V.34, or incorporate new features
such as voice control or a digital answering machine.

OTP - One Time Programmable

An OTP is a PROM (Programmable Read-Only-Memory) device. Once
your program is written into the device with a standard EPROM
programmer, it can not be erased or modified. This is usually
used for limited production runs before a ROM mask is done in
order to test code.

A OTP (One Time Programmable) part uses standard EPROM, but the
package has no window for erasing. Once your program is written
into the device with a standard EPROM programmer, it cannot be
erased or modified. (Well, sort of - any bit that is a one can be
changed to a zero - but a bit that is a zero cannot be changed
into a one).

As product design cycles get shorter, it is more important for
micro manufacturers to offer OTPs as an option. This was commonly
used for limited production runs before a ROM mask in order to
test code. However, one problem with Mask ROM is that
programming, setup, and engineering charges make it economical
only when the systems manufacturer purchases large quantities of
identically programmed micros. Then when you discover THAT bug
(and find it and fix your code), you have quantities of *old
buggy* micros around that you have to throw away. Not to mention
that lead time (the time when you submit your code to the micro
manufacture, to the time you receive your micro with your code on
it) can be at least 8 weeks, and as bad as 44 weeks.

Software protection

Either by encryption or fuse protection, the programmed software
is protected against unauthorized snooping (reverse engineering,
modifications, piracy, etc.).

This is only an option on OTPs and Windowed devices. On Masked
ROM devices, security is not needed - the only way to read your
code would be to rip the microcontroller apart with a scanning
electron microscope - and how many people really have one of
those?

Although - and this is a manufacturer's little know fact - when a
silicon manufacturer makes your ROMed microcontroller - they have
to test it in order to make sure that it is programmed properly.
(You should see what a spec of dust does on a mask :-) In order
to test this, they must be able to read out the ROM and compare it
to the code you submitted. This mode is known as test mode. IN
TEST MODE YOU CAN READ OUT THE ROM OF ANY DEVICE. Anybody who
tells you different, does not know what they are talking about -
or is lying. This is usually not a big deal because test mode is
***VERY*** confidential, and (usually) only known by that
manufacturer (i.e. you cannot put a device into test mode by
accident). Test mode is ONLY applicable with ROMed devices.

4.4) Power Management and Low Voltage

Low voltage parts

Since automotive applications have been the driving force behind
most microcontrollers, and 5 Volts is very easy to do in a car,
most microcontrollers have only supported 4.5 - 5.5 V operation.
In the recent past, as consumer goods are beginning to drive major
segments of the microcontroller market, and as consumer goods
become portable and lightweight, the requirement for 3 volt (and
lower) microcontrollers has become urgent (3 volts = 2 battery
solution / lower voltage = longer battery life). Most low voltage
parts in the market today are simply 5 volt parts that were
modified to operate at 3 volts (usually at a performance loss).
Some micros being released now are designed from the ground up to
operate properly at 3.0 (and lower) voltages, which offer
comparable performance of the 5 volt devices.

Now, why are voltages REALLY going down on ICs? Paul K. Johnson
(of Hewlett-Packard) explains:

There are a few interesting rules of thumb regarding transistors:
1) The amount of power they dissipate is proportional to their
size. If you make a transistor half as big, it dissipates
half as much power.
2) Their propagation delay is proportional to their size. If you
make a transistor half as big, it's twice as fast.
3) Their cost is proportional to the square of their size. If
you make them half as big, they cost one quarter as much.

If you make a transistor smaller, you improve the power, speed,
and cost. The only drawback is that they are harder to make.
(Hey, how hard can it be for HP, IBM, Motorola, National, etc?
ed.) Everybody in the world wants to make transistors smaller and
smaller, the advantages are enormous.

For years people have been using 5 Volts to power IC's. Because
the transistors were large, there was little danger damaging the
transistor putting this voltage across it. However, now that the
transistors are getting so small, 5 Volts will actually fry them.
The only way around this is to start lowering the voltage. This
is why people are now using 3 (actually 3.3) Volt logic, and lower
in the next few years. It isn't just because of batteries.

Brownout Protection

Brownout protection is usually an on-board protection circuit that
resets the device when the operating voltage (Vcc) is lower than
the brownout voltage. The device is held in reset and will remain
in reset when Vcc stays below the Brownout voltage. The device
will resume execution (from reset) after Vcc has risen above the
brownout Voltage.

Idle/Halt/Wakeup

The device can be placed into IDLE/HALT mode by software control.
In both Halt and Idle conditions the state of the microcontroller
remains. RAM is not cleared and any outputs are not changed. The
terms idle and halt often have different definitions, depending on
the manufacturer. What some call idle, others may call halt, and
vice versa. It can be confusing, so check the data sheet for the
device in question to be sure.

In IDLE mode, all activities are stopped except:
- associated on-board oscillator circuitry
- watchdog logic (if any)
- the clock monitor
- the idle timer (a free running timer)
Power supply requirements on the microcontroller in this mode are
typically around 30% of normal power requirements of the
microprocessor. Idle mode is exited by a reset, or some other
stimulus (such as timer interrupt, serial port, etc.). A special
timer/counter (the idle timer) causes the chip to wake up at a
regular interval to check if things are OK. The chip then goes
back to sleep.

IDLE mode is extremely useful for remote, unattended data logging
- the microprocessor wakes up at regular intervals, takes its
measurements, logs the data, and then goes back to sleep.

In Halt mode, all activities are stopped (including timers and
counters). The only way to wake up is by a reset or device
interrupt (such as an I/O port). The power requirements of the
device are minimal and the applied voltage (Vcc) can sometimes be
decreased below operating voltage without altering the state
(RAM/Outputs) of the device. Current consumption is typically
less than 1 uA.

A common application of HALT mode is in laptop keyboards. In
order to have maximum power saving, the controller is in halt
until it detects a keystroke (via a device interrupt). It then
wakes up, decodes and sends the keystroke to the host, and then
goes back into halt mode, waiting either for another keystroke, or
information from the host.

Multi-Input Wakeup (National Semiconductor)

The Multi-Input WakeUp (MIWU) feature is used to return (wakeup)
the microcontroller from either HALT or IDLE modes. Alternately
MIWU may also be used to generate up to 8 edge selectible external
interrupts. The user can select whether the trigger condition on
the pins is going to be either a positive edge (low to high) or a
negative edge (high to low).

4.5) I/O

UART

A UART (Universal Asynchronous Receiver Transmitter) is a serial
port adapter for asynchronous serial communications.

USART

A USART (Universal Synchronous/Asynchronous Receiver Transmitter)
is a serial port adapter for either asynchronous or synchronous
serial communications. Communications using a USART are typically
much faster (as much as 16 times) than with a UART.

Synchronous serial port

A synchronous serial port doesn't require start/stop bits and can
operate at much higher clock rates than an asynchronous serial
port. Used to communicate with high speed devices such as memory
servers, display drivers, additional A/D ports, etc. Can also be
used to implement a simple microcontroller network.

SPI (Motorola)

An SPI (serial peripheral interface) is a synchronous serial port.

SCI

An SCI (serial communications interface) is an enhanced UART
(asynchronous serial port).

I2C bus - Inter-Integrated Circuit bus (Philips)

The I2C bus is a simple 2 wire serial interface developed by
Philips. It was developed for 8 bit applications and is widely
used in consumer electronics, automotive and industrial
applications. In addition to microcontrollers, several
peripherals also exist that support the I2C bus.

The I2C bus is a two line, multi-master, multi-slave network
interface with collision detection. Up to 128 devices can exist
on the network and they can be spread out over 10 meters. Each
node (microcontroller or peripheral) may initiate a message, and
then transmit or receive data. The two lines of the network
consist of the serial data line and the serial clock line. Each
node on the network has a unique address which accompanies any
message passed between nodes. Since only 2 wires are needed, it
is easy to interconnect a number of devices.

MICROWIRE/PLUS (National Semiconductor)

MICROWIRE/PLUS is a serial synchronous bi-directional
communications interface. This is used on National Semiconductor
Corporation's devices (microcontrollers, A/D converters, display
drivers, EEPROMS, etc.).

CAN & J1850

CAN (Controller Area Network) is a mutiplexed wiring scheme that
was developed jointly by Bosh and Intel for wiring in automobiles.
J1850 is the SAE (Society of Automotive Engineers) multiplexed
automotive wiring standard that is currently in use in North
America.

Both of these groups have the "NOT INVENTED HERE" syndrome and
refuse to work with each other's standard. The standards are quite
different and are not compatible at all.

The CAN specification seems to be the one that is being used in
industrial control both in North American and Europe. With lower
cost microcontrollers that support CAN, CAN has a good potential
to take off.

Ken Tindell points out that although the J1850 and CAN buses are
incompatible at an electrical level, they are almost the same at a
higher level. They both use short-frame priority arbitration based
on 29-bit identifiers. At a software-level there is hope. Isn't
there always?

Analog to Digital Conversion (A/D)

Converts an external analog signal (typically relative to voltage)
and converts it to a digital representation. Microcontrollers
that have this feature can be used for instrumention,
environmental data logging, or any application that lives in an
analog world.

The various types of A/D converters that can be found:

Succesive Approximation A/D converters -- This the most common
type of A/D and is used in the majority of microcontrollers. In
this technique, the converter figures out each bit at a time (most
significant first) and finds if the next step is higher or lower.
This way has some benefits - it takes exactly the same amount of
time for any conversion - it is very common - (and therefore very
cheap). However it also has some disadvantages - it is slow - for
every bit it takes at least one clock cycle - the best an 8-bit
A/D can do is at least 8 clock cycles (and a couple for
housekeeping). Because it takes so long - it is a power hog as
compared to the other types of A/Ds.

Single Slope A/D converters -- This is the type of converter that
you can build yourself (if the microcontroller has a couple of
analog blocks on it). Your single slope A/D converter would
include Analog Mux / comparator / timer (8-bit timer = 8 bit A/D -
16-bit timer = 16 bit A/D) with input capture and a constant
current source. The only microcontroller (that I know of) that
has all of this on it is National's COP888EK.

First Step is to clear the timer to 0000 and then start it. It is
a simple matter to hang an external capacitor, and charge it with
the constant current source (linearly because of the current
source) when the voltage on the cap exceeds the sampling voltage,
the comparitor toggles, stops the timer - and voila - you have the
voltage in uSecs - with 16-bit accuracy. The only drawback is you
can't really expect 16 bits (14 yes) - the conversion time varies
quite a bit, and it is SLOW.

Delta-Sigma A/Ds converters -- This type of A/D converter is found
on higher-end DSPs. These are the hardest to understand of the
A/Ds because it just makes a best guess (a little National
Semiconductor humor here :-). Delta sigma A/Ds can be broken down
into two main parts.

The modulator which does the A/D conversion and the filter, which
turns the output of the modulator into a format suitible for the
microcontroller (or DSP).

The modulator is very simple - it just compares the input voltage
to the average of the last 100 (or so) modulator outputs and
decides if the input is higher or lower than the average. This
happens millions of times a second, resulting in a high speed
single-bit datastream of 1s and 0s who's *average* is equal to the
input voltage. Becuse the ouput is only a one or a zero, there are
very few sources of errors. This is the main reason that
delta-sigma A/Ds are **very** accurate.

The filter comes after the modulator ... and this filter is
essentially a big DSP block. It must take the very high speed
stream of ones and zeros and turn it into a slower speed stream of
16-bit (or greater) words to be used by the microcontroller. This
process is called decimation and the filter is often called a
"comb filter". Another digital filter follows this stage and
rejects unwanted frequencies. This filter performs a similar
function to the anti-aliasing filter required in many traditional
A/D appliactions, but it does it at an unprecedented level of
performance and at low cost. This is the other major benefit of
delta-sigma A/Ds.

Flash A/D -- This is the basic architecure for the fastest
category of A/Ds. The flash converter involves looking at each
level that is possible and instantaneously saying what level the
voltage is at. This is done by setting up comparators as
threshold detectors with each detector being set up for a voltage
exaclty 1 LSB higher than the detector below it. The benefit of
this architecture is that with a single clock cycle, you can tell
exactly what the input voltage is - that is why it is so fast.
The disadvantage is that to achieve 8-bit accuracy you need 256
comparators and to achieve 10-bit accuracy you need 1024
comparators. To make these comparators operate at higher speeds,
they have to draw LOTS of current, and beyond 10 bits, the number
of comparators required becomes totally unmanageable.

D/A (Digital to Analog) Converters

This feature takes a Digital number and converts it to a analog
output. The number 50 would be changed to the analog output of
(50/256 * 5Volts) = .9765625V on a 8-bit / 5 Volt system.

Pulse width modulator

Often used as a digital-to-analog conversion technique. A pulse
train is generated and regulated with a low-pass filter to
generate a voltage proportional to the duty cycle.

Pulse accumulator

A pulse accumulator is an event counter. Each pulse increments
the pulse accumulator register, recording the number of times this
event has occurred.

Input Capture

Input Capture can measure external frequencies or time intervals
by copying the value from a free running timer into a register
when an external event occurs.

Comparator

One or more standard comparators can sometimes be placed on a
microcontroller die. These comparators operate much like standard
comparators however the input and output signals are available on
the microcontroller bus.

Mixed (Analog-Digital) Signal

We live in an analog world where the information we see, hear,
process, and exchange with each other, and with our mechanical and
electronic systems, is always an analog quantity - pressure,
temperature, voltage, current, air and water flow are always
analog entities. They can be digitized for more efficient
sorting, storage and transmittal, but the interface - the input
and output - is almost always analog. Thus the essence of analog
electronics lies in sensing continuously varying information,
shaping and converting it for the efficiency of digital processing
and transmission, and reshaping the digital data to an analog
signal at the other end.

Mixed analog-digital devices are being used increasingly to
integrate the complex functions of high-speed telecommunications,
or the real-time data processing demanded by industrial control
systems and automotive systems. Start looking for
microcontrollers that have analog comparators, analog
multiplexers, current sources, voltage doublers, PLL (Phase Lock
Loops) and all sorts of peripherals that you thought were analog
only.

4.6) Interrupts

Polling

Polling is not really a "feature" - it's what you have to do if
your microcontroller of choice does not have interrupts.
Polling is a software technique whereby the controller continually
asks a peripheral if it needs servicing. The peripheral sets a
flag when it has data ready for transferring to the controller,
which the controller notices on its next poll. Several such
peripherals can be polled in succession, with the controller
jumping to different software routines, depending on which flags
have been set.

Interrupts

Rather than have the microcontroller continually polling - that
is, asking peripherals (timers / UARTS / A/Ds / external
components) whether they have any data available (and finding most
of the time they do not), a more efficient method is to have the
peripherals tell the controller when they have data ready. The
controller can be carrying out its normal function, only
responding to peripherals when there is data to respond to. On
receipt of an interrupt, the controller suspends its current
operation, identifies the interrupting peripheral, then jumps
(vectors) to the appropriate interrupt service routine.

The advantage of interrupts, compared with polling, is the speed
of response to external events and reduced software overhead (of
continually asking peripherals if they have any data ready).

Most microcontrollers have at least one external interrupt, which
can be edge selectible (rising or falling) or level triggered.
Both systems (edge/level) have advantages. Edge - is not time
sensitive, but it is susceptible to gitches. Level - must be held
high (or low) for a specific duration (which can be a pain - but
is not susceptible to glitches).

Interrupts are critical when you are controlling anything (this is
what microcontrollers do). If you misunderstand any of the terms,
and design your systems with the way you *think* it works - not
the way it *really* works - it will effect system performance. It
may also work for a very long time with no problems, and then all
of a sudden fail. Check your datasheets - these descriptions are
the correct ones (or are at least supposed to be), but that does
not mean that they are agreed to by the silicon manufacturers, (or
by the marketing guys that they employ, and who write parts of the
data sheets.)

4 bit microcontrollers usually have either a polling or
non-vectored type of interrupt scheme. 8 and 16 bit
microcontrollers usually have some type of vectored arbitration
type of interrupt scheme. 32 bit microcontrollers usually will
have some type of vectored priority type of interrupt scheme.
Again, check your data sheet to make sure - or ask a
manufacturer's rep if you aren't sure.

Maskable Interrupts

A maskable interrupt is one that you can disable or enable
(masking it out means disabling the interrupt), whereas
non-maskable interrupts you can't disable. The benefit of
maskable interrupts is that you can turn off a particular
interrupts (for example a UART) during some time critical task.
Then, those particular interrupts will be ignored thus allowing
the microcontroller to deal with the task at hand. Most
microcontrollers (as well as most microprocessors) have some type
of Global Interrupt Enable (GIE) which allows you to turn off (or
on) all of the maskable interrupts with one bit. NOTE: GIE
usually does not effect any NMI (Non-Maskable Interrupts)

Vectored Interrupts

Simple (non-vectored) interrupts is one of the simplest interrupt
schemes there is (Simple = less silicon = more software = slower).
Whenever there is an interrupt, the program counter (PC) branches
to one specific address. At this address, the system designer
needs to check the interrupts (one at a time) to see which
peripheral has caused the interrupt to occur. Code for this may
look like (on a COP8):

IFBIT UART,PSW ; If the UART bit has been set
JP UART_Recieve ; Jump to the UART receive service routine

IFBIT T1,PSW ; If the timer has underflowed
JP Underflow ; Jump to the underflow service routine

... and so on

This can be *very* slow - and the time between the interrupt
happening and the time the service routine is entered, depends on
how the system designer sets up their ranking. The peripheral
that is checked last takes the longest to process. Most
microcontrollers that have fewer than 3 - 5 interrupts use this
method. The benefit of this is that the system designer can set
the priority - The most important peripheral gets checked first -
and you get to decide which peripheral that is.

Vectored interrupts are a little easier to set up, but the system
designer has less control of the system (i.e. is dependent on the
silicon manufacture to make the proper decisions during design of
the chip). When an interrupt occurs, the hardware interrupt
handler automatically branches to a specific address depending on
what interrupt occurred. This is much faster than the
non-vectored approach described above, however the system designer
does not get to decide what peripheral gets checked first.
Example (on a National Semiconductor COP888CG):

Rank Source Description Vector Address
------------------------------------------------------------------
1 (highest) Software INTR Instruction 01FE - 01FF
2 External Pin G0 Edge 01FA - 01FB
3 Timer T0 Underflow 01F8 - 01F9
4 Timer T1 T1A / Underflow 01F6 - 01F7
5 Timer T1 T1B 01F4 - 01F5
6 MICROWIRE/PLUS BUSY Goes Low 01F2 - 01F3
7 UART Receive 01EE - 01EF
8 UART Transmit 01EC - 01ED
9 Timer T2 T2A / Underflow 01EA - 01EB
10 Timer T2 T2B 01E8 - 01E9
11 Timer T3 T3A / Underflow 01E6 - 01E7
12 Timer T3 T3B 01E4 - 01E5
13 Port L / MIWU Port L Edge 01E2 - 01E3
14 (lowest) Default VIS Interaction 01E0 - 01E1

In ROM location 01F8 - 01F9 (2bytes x 8 bits = 16bit address) the
system designer enters the ROM location of where they want the
service routine (of the Timer T0 underflow) to be. And so on for
the rest of the addresses.

Interrupt arbitration and priority

Interrupt arbitration and priority - These are two of the most
misused words when it comes to microcontrollers (microprocessors
too for that matter) and it's generally because no one knows the
difference between them. Priority is not Arbitration.
Arbitration is not Priority. Lets see if we can sort out the
differences.

Arbitration - If you look at the above chart of the COP888CG, you
may think the interrupts are prioritized because they have some
ranking. They do have rank, but they are not prioritized. What
happens is that (in an arbitration scheme) when an interrupt
occurs, the GIE (Global Interrupt Enable) is cleared. This
effectively means that all future interrupts will be delayed until
the GIE is set. The GIE becomes set only if the system designer
sets it in a service routines, or on a RETI (Return from
Interrupt).

Quick Example 1 - Timer 1 underflows - the hardware clears the
GIE, looks at ROM locations 01F6 and 01F7 and jumps to the ROM
location pointed to by those addresses. The program does a couple
things, and then sets the GIE (because the user wants to recognize
an external interrupt during this service routine). However while
in the service routine, Timer 3 underflows. Although a timer 3
underflow is lower in rank than a timer 1 underflow, the interrupt
handler does not care - it simply looks at the GIE, and because it
is set - handles the interrupt (now we have nested interrupts).
The Timer 1 underflow service routine will not be completed until
the Timer 3 underflow is complete.

Quick Example 2 - Timer 3 underflows at the same time as an
External interrupt occur. The one to be handled first is the
External Interrupt. If the user sets the GIE, the interrupt
handler will jump down to the Timer 3 underflow handler. If the
user does not set the GIE, the microcontroller handles the
External interrupt, does a RETI, and the Timer 3 underflow can now
be handled.

Priority - In a priority scheme, things are prioritized (well,
what'd you expect?). If Timer T0 underflows, the only thing that
can interrupt that is an external or software interrupt. If a
external or software interrupt occurs, the interrupt handler will
branch to these service routines. When they are complete, it will
return to the Timer T0 underflow.

Quick Example - In the below timing diagram, the following
happens:
1) Timer T0 underflows
2) Timer T2 underflows
3) An External Interrupt occurs.

In a priority scheme, the following would happen:

External Interrupt |---------|
| |
Timer T0 Underflow |-------| |------|
| |
Timer T2 Underflow | |------|
| |
Normal Execution ---| |-------

^ ^ ^ ^ ^ ^
| | | | | |
Time -> | | | | | \-T2 Done
| | | | \-------- T0 Done
| | | \-------------- Ext Done
| | \------------------------ Ext Edge
| \----------------------- T2 Underflows
\--------------------------- T0 Underflows

This is what RTOS (Real Timer Operating Systems) do - prioritize
and handle interrupts.

4.7) Special microcontroller features

Watchdog timer

A watchdog timer provides a means of graceful recovery from a
system problem. This could be a program that goes into an endless
loop, or a hardware problem that prevents the program from
operating correctly. If the program fails to reset the watchdog
at some predetermined interval, a hardware reset will be
initiated. The bug may still exist, but at least the system has a
way to recover. This is especially useful for unattended systems.

Digital Signal Processors (DSP)

Microcontrollers react to and control events - DSPs execute
repetitive math-intensive algorithms. Today many embedded
applications require both types of processors, and semiconductor
manufacturers have responded by introducing microcontrollers with
on-chip DSP capability and DSPs with on-chip microcontrollers.

The most basic thing a DSP will do is a MACC (Multiply and
ACCumulate). The number of data bits a DSP can Multiply and
ACCumulate will determine the dynamic range (and therefore the
application).

Bits Fixed/Floating Dynamic Range Typical Application

8 Fixed 48 dB Telephone-quality voice
16 Fixed 96 dB Compact disk (marginal)
24 Fixed 144 dB Compact disk
(room for error)

Clock Monitor

A clock monitor can shut the microcontroller down (by holding the
microcontroller in reset) if the input clock is too slow. This
can usually be turned on or off under software control.

Resident program loader

Loads a program by Initializing program/data memory from either a
serial or parallel port. Convenient for prototyping or trying out
new features, eliminates the erase/burn/program cycle typical with
EPROMs, and allows convenient updating of a system even from an
offsite location.

Monitor

A monitor is a program installed in the microcontroller which
provides basic development and debug capabilities. Typical
capabilities of a microcontroller monitor include: loading object
files into system RAM, executing programs, examining and modifying
memory and registers, code disassembly, setting breakpoints, and
single-stepping through code. Some simple monitors only allow
basic functions such as memory inspection, and the more
sophisticated monitors are capable of a full range of debug
functions.

Monitors can either communicate with a dumb terminal or with a
host computer such as a PC. Much of the work of the monitor (such
as user interface) can be offloaded to the host PC running a
program designed to work with the monitor. This makes it possible
to reduce the size and complexity of the code that must be
installed in the target system.

MIL transducer

An MIL transducer is a sophisticated and expensive device that
detects the presence of your mother-in-law. Sensitivity settings
are possible for a full range of stimuli such as: snarling,
stomping, nasty faces, and others. Techno-Wimp (address withheld
upon request), the sole manufacturer of the MIL transducer, has
recently announced a major new version which is sensitive enough
to detect less-tangible stimuli. This breakthrough product is
dubbed the MIL-WOMF ("Whoa, outta my face!") transducer. Both the
original MIL and the new MIL-WOMF transducers are programmable and
easy to interface to most microcontrollers.

5) Some popular microcontrollers

Some common microcontrollers are described below. A common question
is "what microcontroller should I use for...?" Well, that's a tough
one. The best advice would be to choose a chip that has a full set
of development tools at the price you can afford, and good
documentation. For the hobbyist, the Intel 8051, Motorola 68hc11, or
Microchip PIC would all make suitable choices.

8048 (Intel)

The grandaddy of 'em all, the first microcontroller, it all
started here! Although a bit long in the tooth and a bit kludgey
in design (at least by today's standards), it is still very
popular due to its very low cost, availability, and wide range of
development tools.

Modified Harvard architecture with program ROM on chip with an
additional 64 to 256 bytes of RAM also on chip. I/O is mapped in
its own space.

8051 (Intel and others)

The 8051, Intel's second generation of microcontrollers, rules the
microcontroller market at the present time. Although featuring a
somewhat bizarre design, it is a very powerful and easy to program
chip (once you get used to it).

Modified Harvard architecture with separate address spaces for
program memory and data memory. The program memory can be up to
64K. The lower portion (4K or 8K depending on type) may reside on
chip. The 8051 can address up to 64K of external data memory, and
is accessed only by indirect addressing. The 8051 has 128 bytes
(256 bytes for the 8052) of on-chip RAM, plus a number of special
function registers (SFRs). I/O is mapped in its own space.

The 8051 features the so-called "boolean processor". This refers
to the way instructions can single out bits just about anywhere
(RAM, accumulators, I/O registers, etc.), perform complex bit
tests and comparisons, and then execute relative jumps based on
the results.

Piles of software, both commercial and free, are available for the
8051 line. Many manufacturers supply what must be a hundred
different variants of this chip for any requirement. Often
featured in construction projects in the popular hobbyist
magazines.

80c196 (MCS-96)

The third generation of Intel microprocessors, the 80c196 is a 16
bit processor. Originally fabricated in NMOS (8096), it is now
mainly available in CMOS. Intel Corp. has recently introduced a
clock-doubled (50MHz) version of the 80c196.

Among the many features it includes are: hardware multiply and
divide, 6 addressing modes, high speed I/O, A/D, serial
communications channel, up to 40 I/O ports, 8 source priority
interrupt controller, PWM generator, and watchdog timer.

80186,80188 (Intel)

These chips are, in essence, microcontroller versions of the 8086
and 8088 (of IBM/PC fame). Included on the chip are: 2 channels
of DMA, 2 counter/timers, programmable interrupt controller, and
dynamic RAM refresh. There are several variations including: low
power versions, variations with serial ports, and so on.

One major advantage you gain by using one of these parts is that
you can use standard PC development tools (compilers, assemblers,
etc) for developing you applications. If you are already familiar
with PC software development, the learning curve will be short,
since these chips have the same basic architecture as the original
8088 (as used in the IBM/PC).

Other advantages include high speed processing, a full megabyte
addressing space, and powerful interrupt processing.

80386 EX (Intel)

The 80386 EX is of course a 386 in microcontroller clothing.
Included on the chip are: serial I/O, power management, DMA,
counter/timers, programmable interrupt controller, and dynamic RAM
refresh. And of course, all of the power of the 386
microprocessor.

One major advantage you gain by using one of these parts is that
you can use standard PC development tools (compilers, assemblers,
etc) for developing your applications. If you are already
familiar with PC software development, the learning curve will be
short, since these chips have the same basic architecture as the
original 8088 (as used in the IBM/PC).

We're talking power here gang. Now let's all wait for Microsoft
to release a version of Windows for embedded and real-time
applications (Windows ET? Windows RT? Windows 2000? :-).

65C02/W65C816S/W65C134S (Western Design Center)

The Western Design Center, Inc. is the original owner and designer
of the 65C02 8-bit microprocessor, used in the original Apple,
Commodore, and Atari computers. WDC has subsequently developed a
16-bit MPU (W65C816S), an 8-bit microcontroller (with 65C02 as the
core) named W65C134S, and a 16-bit microcontroller (with 65C816 as
core). These are sold off-the-shelf and the the module technology
is licensed for use in ASIC designs.

WDC has recently come out with their .8u 134S and 265S. There are
many companies who have or are designing in these parts into their
board-level system design. It is expected that this new version's
performance to be greatly enhanced over the previous 1.2u. They
are also working with their foundry to add EE and Flash versions
to their standard product offering.

The Western Design Center
2166 East Brown Rd.
Mesa, AZ 85213
(602)962-4545 Fax: (602)835-6442
Email: wdes...@wdesignc.com
Web: http://www.wdesignc.com

6805 (Motorola)

The 6805 is based loosely on the manufacturer's earlier 6800, with
some similarities to the 6502. It has a Von-Neuman architecture
in which instructions, data, I/O, and timers all share the same
space. Stack pointer is 5 bits wide which limits the stack to 32
bytes deep. Some members of this family include on chip A/D, PLL
frequency synthesizer, serial I/O, and software security.

68hc11 (Motorola and Toshiba)

The popular 68hc11 is a powerful 8-bit data, 16-bit address
microcontroller from Motorola (the sole supplier) with an
instruction set that is similar to the older 68xx parts (6801,
6805, 6809). The 68hc11 has a common memory architecture in which
instructions, data, I/O, and timers all share the same memory
space.

Depending on the variety, the 68hc11 has built-in EEPROM/OTPROM,
RAM, digital I/O, timers, A/D converter, PWM generator, pulse
accumulator, and synchronous and ansynchronous communications
channels. Typical current draw is less than 20ma.

683xx (Motorola)

The MC68EC300 series incorporates various peripherals into various
68k family core processors. These can be called "integrated
processors". They are really super-microcontrollers, very high
performance, capable of high processing speeds, and able to
address large amounts of memory. A typical example from this line
would be the 68331. It is based on a 68020-like core and has
about the same processing power as an Intel 80386.

PIC (MicroChip)

While watching my 8 year old daughter play with her Barbie Dolls
(she has about 7 or so, including two that used to belong to Roz,
my wife, when she was a girl) I noticed an interesting difference
between the old dolls and the new dolls. The old Barbies could
only move their heads sideways, while the new Barbies not only can
move their heads sideways, but also up and down. AMAZING - the
old Barbies were good girls - they could only say no. The new
Barbies however can also say yes. Progress - isn't it wonderful!
(Not to mention the gymnast Barbie that Dave Perry's daughter got
for Christmas - "wait'll you see what *she* can do ;-)"

Which leads me to an amazing fact. Most everyone thinks of the
PIC microcontroller line as being a recent introduction. However,
they've been popular for over 20 years. What's the difference?
Microchip (which was originally [owned by] General Instruments),
seems to have recreated this microcontroller into a product
universally regarded as a powerful and cost effective solution.
The new chips are fabricated in CMOS, some features have been
added, and new family lines have been introduced.

The PIC microcontrollers were the first RISC microcontrollers.
RISC generally implies that simplicity of design allows more
features to be added at lower cost, and the PIC line is no
exception. Although having few instructions (eg. 33 instructions
for the 16C5X line versus over 90 for the Intel 8048), the PIC
line has a wealth of features included as part of the chip.
Separate buses for instructions and data (Harvard architecture)
allows simultaneous access of program and data, and overlapping of
some operations for increased processing performance. The
benefits of design simplicity are a very small chip, small pin
count, and very low power consumption.

PIC microcontrollers are rapidly gaining in popularity. They are
being featured more and more often in construction projects in
popular hobbyist magazines, and are chalking up a good number of
design wins. Due to their low cost, small size, and low power
consumption, these microcontrollers can now be used in areas that
previously wouldn't have been appropriate (such as logic
circuits). They are currently available in three lines: the
PIC16C5x, PIC16Cxx, and PIC17Cxx families.

PSST! Hey kid! Want a naked Barbie Doll?!

COP400 Family (National Semiconductor)

The COP400 Family is a P2CMOS 4-bit microcontroller which offers
512 bytes to 2K ROM and 32x4 to 160x4 RAM. Packages are varied
from 20 to 28 pin (DIP/SO/PLCC). Functions include Microwire,
timers counters, 2.3 to 6.0 Volt operation, ROMless modes, and OTP
support.

Far from being "old" technology - 4-bit microcontrollers are
meeting significant market needs in more applications than ever
before. The reason for the continuing strength of the COP400
family is its versatility. Over 60 different, compatible devices
are available for a wide range of requirements. The first under
$.50 microcontroller set a new standard of value for
cost/performance.

COP800 Family (National Semiconductor)

The COP800 Basic Family is a fully static 8-bit microcontroller,
fabricated using double metal silicon gate microCMOS technology.
This low cost microcontroller contains all system timing,
interrupt logic, ROM, RAM, and I/O necessary to implement
dedicated control functions in a variety of applications.

Depending on the device, features include: 8-bit memory mapped
architect, MICROWIRE serial I/O, UART, memory mapped I/O, many 16
bit timer/counters with capture registers, a multi-sourced
vectored interrupt, comparator, WATCHDOG Timer and Clock monitor,
Modulator/Timer (high speed PWM timer for IR transmission),
8-channel A/D converter with prescaler and both differential and
single-ended modes, brownout protection, halt mode, idle mode,
high current I/O pins with 15mA sink capability, Schmitt trigger
inputs and Multi-Input-Wake-Up. Most devices operate over a
voltage range from 2.5V to 6V.

High throughput is achieved with an efficient, powerful
instruction set operating at a 1uS per instruction rate (most
instructions are single byte/single cycle) including true bit
manipulation and BCD arithmetic instructions. Most devices have
military versions for -55C to +125C.

HPC Family (National Semiconductor)

The HPC Family of High Performance microControllers is a 16-bit
controller fabricated using National's advanced microCMOS
technology. This process combined with an advanced architecture
provides fast, flexible I/O control, efficient data manipulation,
and high speed computation.

With its 16x16 bit multiply and 32x16 bit divide, the HPC is
appropriate for compute-intensive environments that used to be the
sole domain of the microprocessor. The architecture is a
Von-Neuman architecture where the program and data memory share
the same address space.

Depending on the family member, features include: 16-bit
memory-mapped architecture with software configurable external
address/data bus, Microwire/Plus serial I/O, UART, 16-bit
timer/counters with input capture capability, High-Level Data Link
Control (HDLC) for ISO-standard data communications, 8-channel A/D
converter with prescaler and both differential and single-ended
modes, power-saving modes, Multiply/Accumulate Unit with built-in
circular buffer management for low to medium DSP applications,
software configurable chip-select outputs, 64KB address space
directly addressable, low-voltage (3.3V) operation.

High throughput is achieved with an efficient, powerful
instruction set operating at a 50ns per instruction cycle (most
instructions are single byte/single cycle) including true bit
manipulation. Key applications currently using the HPC family
include: Anti-lock Braking Systems, Hard Disk drives for mass
storage, telecommunications, security systems, laser printers, and
some military applications.

Project Piranha (National Semiconductor)

Project Piranha is an internal code name for National
Semiconductor's embedded RISC processor technology. The Piranha
technology represents the first RISC processor specifically
designed for the needs of embedded applications. This was
accomplished through examination of the needs of typical embedded
applications, resulting in a technology which maintains the
benefits of CISC while providing the performance of RISC.

Specifically, some of these benefits are:
compact code density --> smaller memory usage/
lower system cost
small core size --> more room for add-on system design
scalable architecture --> a range of performance solutions
from 8 to 64 bits with a common architecture
common instruction set --> you only face the learning curve
and development tools once
modular design --> designed for easy integration of
specialized functions into
single chip

This technology is initially being implemented in application
specific products from National Semiconductor, with the first
product being available in Q1, 1995. For further information on
this technology, please contact Mark Throndson at
tme...@esd.nsc.com, or (408) 721-4957.

Z8 (Zilog)

A "loose" derivative of the Zilog Z80, the Z8 is actually a
composite of several different achitectures. Not really
compatible with the Z80 peripherals. Has a unique architecture
with three memory spaces: program memory, data memory, and a CPU
register file. On-chip features include UART, timers, DMA, up to
40 I/O lines. Some versions include a synchronous/asynchronous
serial channel. Features fast interrupt response with 37
interrupt sources. The Z8671 has Tiny Basic in ROM. The Super-8
is just that, a super version of the Z8 with more of everything.

There seem to be quite a few new members of the zilog Z8 family
arriving recently, including chips such as the Z86C95 which
contains a fairly "normal" Z8 but with lots of registers (not the
normal 128, but 236), and an internal 16 bit harvard architecture
DSP with two data memory systems and one program memory system,
and with a 24 bit accumulator. The DSP unit has its memory
systems accessible as additional banks of Z8 registers (the exact
mechanism is very poorly explained in the documentation!) so the
Z8 can be used to write the data and code for the DSP into the
DSP's storage and then start the DSP running, etc. There are the
usual Z8 peripherals plus A/D and D/A (single channel, accessible
by the Z8 and DSP CPUs).

Zilog has also recently come out with some new OTP parts:
osc
part# PDIP EPROM RAM I/O type freq
---------------------------------------------------------------
Z86E04 18 pin 1K 124 bytes 14 pins xtal,LC, 8MHz
cer res,ext
Z86E08 18 pin 2K 124 bytes 14 pins xtal,LC, 12MHz
cer res,ext
Z86E30 28 pin 4K 237 bytes 24 pins xtal,LC,RC, 12MHz
cer res,ext
Z86E31 28 pin 2K 124 bytes 24 pins xtal,LC,RC, 8MHz
cer res,ext

All parts come with real configurable RAM stack and interrupt
systems, two fully programmable timers with interrupts, ROM
protect, low-EMI modes, two analog comparator inputs with
interrupt capability, low-power standby modes (as low as 1 uA) and
45 easy instruction set. There are no separate chip versions to
do each of the oscillator types, one chip does them all.

HD64180 (Hitachi)

A powerful microcontroller with full Z80 functionality plus:
extended memory management, two DMA channels, synchronous and
asynchronous communications channels, timers, and interrupt
controller. Some versions of this chip also include EPROM, RAM,
and PIO (programmable input/output). It runs Z80 code in fewer
clock cycles than the Z80 and adds in hardware multiply and a few
other instructions. Available in versions that run up to 18MHz.

TMS370 (Texas Instruments)

It is similar to the 8051 in having 256 registers, A and B
accumulators, stack in the register page, etc. It also has a
host of onboard support devices, some members have all of them
while others have a subset, the peripherals include: RAM, ROM
(mask, OTP, or EEPROM), 2 timers (configurable as timers/
counters/comparators/PWM output), watchdog timer, SCI (syncronous
serial port), SPI (asynchronous serial port), A/D (8 bit, 8
channel), interrupts.

Instruction set is mostly 8 bit with some 16 bit support. Has
several addressing modes, 8x8 multiply, 16/8 divide. Clock speeds
are up to 20MHz which gives 5MHz for buss access and instruction
cycles. Pins mostly TTL compatible (except clock and reset).

Packages include:
28,40 DIP
28 CLCC
28,44,68 PLCC
40,64 SDIP

A developers/proto board is available. It is a multi layer PCB
about 12"x7" with RS-232 serial I/O, and monitor as well as access
to all processor pins on a patch and proto area. Support software
includes IBM-PC monitor & loader, cross assembler (absolute only).
A pure serial TTY monitor is also supported. Sole power
requirement is +5v. Priced is about $500 or so.

A relocating assembler and linker, and a C compiler are also
available.

1802 (RCA)

This is a real old-timer. The 1802 is the successor to the 1801
(2 chip set) which was the first microprocessor implemented in
CMOS. Both products were called microprocessors by RCA, not
microcontrollers. However, since the 1801 was implemented in CMOS
and therefore had low power requirements, it was often used in
microcontroller applications. The 1802, with its higher level of
integration and ease of use, could actually be considered a true
microcontroller. The 1802 is radiation hard and used in a lot of
deep space and satellite applications.

The 1802 has a fairly clean instruction set, a bunch of
general-purpose registers (more like a Z80 than an 8051 in that
regard), and separate data and I/O address spaces.

MuP21 (Forth chip)

The MuP21 was designed by Chuck Moore, the inventor of Forth.
With the MuP21, Forth can compile into machine code and still be
Forth, because the machine code IS Forth. The MuP21 freaks out at
100 MIPS while consuming only 50 milliwatts. Not only that, the
chip includes a video generator, has only about 7000 transistors
(that's right, 7000 and not 7,000,000), and costs about $20.

The assembler on this chip is a sort of dialect of Forth, as the
CPU is modeled after the Forth virtual machine. MuP21 is a
MINIMAL Forth engine. In fact MuP21 was designed to run OKAD
(Chuck Moore's VLSI CAD softare), and OKAD was designed to run on
MuP21. OKAD was run on a 486 to design MuP21, and MuP21 was
designed to have just enough hardware to run OKAD about ten times
as fast as a 486 on a very cheap chip (the MuP21). That's the
reason for the MuP21's on-chip video generator coprocessor. The
CPU programs the video generator and then just manipulates the
video buffer. It is composite video out, so it only needs one
pin. MuP21 is only a 40 pin chip.

MuP21 chips, boards, software, manuals, and spec sheets are
available from:
Offete Enterprises
1306 South B Street, San Mateo CA 94402
(415) 574-8250
Email: tin...@ccmail.apldbio.com
tin...@perkin-elmer.com.

F21 (Next generation Forth chip)

F21 will be bigger (10k vs 7k transistors for the MuP21!) but
since it is going to implemented with a smaller geometry (.8
micron vs 1.2) it will still be extremely small and low power, and
low cost. Although the specs on this chip aren't final yet,
expected performance is in the range of 250 MIPS!!. It will have
multiple analog processors and a very high speed serial network
coprocessor on chip. F21 will also support a wider range of
memory chips and have more I/O processors.

Designed for cheap consumer multimedia and parallel processing,
the F21 is planned for release some time in 1995.

For more information on this project, contact: Jeff Fox
<jf...@netcom.com>.

6) GETTING STARTED WITH MICROCONTROLLERS

In order to get started with microcontrollers, several factors need
to be considered.
- cost
- convenience
- availability of development tools
- intended use

The hardware described in this section is readily available,
affordable, and is easy to find software for.

<Inclusion or exclusion of a product in this section doesn't have any
real significance. I've tried to give a good cross-section of
devices and manufacturers - I'm open for suggestions.>

6.1) Evaluation Kits/Boards

Many manufacturers offer assembled evaluation kits or boards which
usually allow you to use a PC as a host development system. Among
some of the more popular evaluations kits/boards are:

Parallax Basic Stamp
This is a small single-board controller that runs BASIC, and costs
only $39. A SIP version for only $29 is also available. THE 256
byte EEPROM can hold a program of up to about 100 instructions.
The BASIC Stamp Programming Package is a complete development
package for only $99.
Parallax, Inc., 3805 Atherton Rd. 102, Rocklin, CA 95765
(916)624-8333 Fax: (916)624-8003 BBS: (916)624-7101
email: in...@parallaxinc.com

Motorola EVBU, EVB, EVM, EVS
A series of very popular evaluation/development systems based on
the 68hc11. Comes complete with the BUFFALO monitor and varying
types of development software. Commonly used for university
courses.

Motorola 68705 starter kit
Motorola supplies a complete development system, -- software,
hardware, simulator, emulator, manuals, etc for just $100.

Dallas Semiconductor DS5000TK
The DS5000TK allows evaluation of any DS5000 series device in any
existing application without circuit changes. The included
DS5000T plugs into the supplied serial interface pod which
provides a connection to a host PC. A target cable connects the
pod to the target system. Programs can be downloaded directly to
the chip (no EPROM programming!) using the built-in serial loader.
(With Dunfield's Development System, you end up with a cheap
"pseudo-ice". Dunfield also has a circuit if you want to build a
similar device.)

Philips/CEIBO DS750
For $100 (from Philips, from CEIBO the price is $250), you get a
"pseudo-ice" for testing your code in-circuit. Based on the
low-end Philips 87c75x parts. Allows source-code debugging in
assembler (included), C, and PL/M, with an interface similar to
that of Borland's Turbo Debugger. Very popular with students and
consultants for experimenting with 80c51 code. Includes a VERY
NICE book which describes the theory of operation of the board
itself, and includes a good number of experiments that you can try
for yourself. Philips sold nearly 10,000 of these boards in the
USA (and 5000 in Europe without even advertising).

National Semiconductor's EPU
The COP8780 Evaluation / Programming Unit (EPU) offers designers a
low-cost ($125) tool for an introduction to National's COP8 Basic
Family of 8-bit microcontrollers. This development tool gives you
an inexpensive way to benchmark and evaluate microcontroller code
in realtime. With its built in MIRCOWIRE/PLUS interface, it can
interface to numerous MICROWIRE/PLUS devices such as EPROMS,
EEPROMS, D/As, A/Ds, DASs, and others, to give a full featured
system. The system includes the EPU board, assembler and debugger
software, sample code, very limited C compiler, wall power supply,
documentation, and a really great box :-).

Zorin BOTBoard
The BOTBoard is a low cost and powerful single board computer
based on the Motorola HC11E series Microcontroller. The Zorin
kits make it easy to create many types of computer controlled
applications. Get the optional servo motors to create walking
machines, robotic arms, animated art and more! Program the
on-chip memory from any computer or terminal using the Buffalo
monitor, or use the PC software included with the kit. The eight
page assembly manual includes example code to operate the servo
motors.
Zorin / POB 30547 / Seattle, WA 98103-0547
(206)282-6061
zch...@eskimo.com

6.2) Easy chips to use

In addition, several chips provide a similar capability if you are
willing to spend a bit of time wiring up a simple circuit. A few
chips worth looking at are:

Motorola MC68HC11A8P1
Contains Motorola's BUFFALO monitor which has the same
functionality as the one on Motorola's evaluation boards. A
working system can be built with this chip and a Maxim MAX-232.
You can talk to it with a PC or Mac over a 3-wire RS232
connection. It is easy to load and run anything you want in the
on-board RAM and EEPROM. You can even use subprograms in the
BUFFALO monitor after getting a listing from Motorola's BBS or ftp
site. This BBS/ftp site also has freeware assemblers to make a
complete development environment cheaply and quickly.

Intel 8052AH-BASIC
This popular chip with hobbyists is another easy way to get
started. You can download high level code from your host. The
disadvantages are that you can't get away from a multi-chip
solution, the code is noticeably slow, you have to buy an MCS
BASIC manual, you are detached from the inner workings, there
aren't many on-chip goodies like A/D, and you can forget about
running off of a battery.

Dallas Semiconductor DS5000/DS2250
These are well suited even for electronics ignoramuses (ignorami?)
such as myself. All you need to add is a crystal and two
capacitors to end up with a working system. These chips come
complete with non-volatile RAM in the form of static RAM (at least
8K) backed up with a lithium battery. Everything is saved -
program, data, and bugs ;-).

MicroChip PIC '5x series
With only 33 instructions, this chip is definitely easy to use!
Using Parallax's assembler, the instruction set is ** MUCH ** less
intimidating than MicroChip's opcodes! These chips simply need
power, ground, and 1 of 4 different timing circuits. Doesn't get
much easier than that! With I/O pins that are beefy (25mA per pin
sink, 20mA per pin source) and drive both high and low,
interfacing is super easy. It's great to hook LEDs and such
directly to output pins with only a resister in-line!

6.3) Software (Cheap and easy)

You can search for free software for development, but you often get
what you pay for. What is sorely lacking in freeware is technical
support. Several packages are available that provide complete
development environments for some of the more popular
microcontrollers. If you want to be productive right away, think
about investing $100 or so - it'll be well worth the price!

I've been playing with the Dunfield Development System lately (on the
8051), and it's really quite nice. I've also heard many good things
about it from others. It includes a near ANSI-C compiler, run-time
library with source, assembler, ROM debugger, integrated development
environment, monitor with source, utilities, and other extras.
Although not freeware, the low price ($100), the features, all of the
extra goodies, and the good reviews make this a package worth looking
at. Also, if you're interested in working on more than one family of
microcontroller, Dunfield supports a wide range. This means only
needing to learn one system, instead of many. The following chips
are supported: 6805, 6809, 68hc11, 68hc16, 8051/52, 8080/85, 8086,
and 8096. A package including a simulator and a resident monitor
debugger are also available for the 8051 for $50.
Dunfield Development Systems
P.O. Box 31044, Nepean, Ontario K2B 8S8 Canada
(613)256-5820 Fax: (613)256-5821
Email: ddun...@bix.com

A decent C compiler for the 68hc11 comes from ImageCraft. This
package, which runs under DOS and OS/2, includes a near ANSI C
compiler, assembler, linker, librarian, ANSI C functions and headers,
and 90 page manual. The current release is version 1.02 of their
compiler. The price is just $40. Initial feedback on this compiler
seems promising. The pre-release versions are already in use by many
of you, and will still be available as freeware.
ImageCraft
P.O. Box 64226, Sunnyvale, CA 94086-9991
(Richard Man) imag...@netcom.com

Another low priced ($100) C compiler comes from Micro Computer
Control. Cross compilers running under DOS are available for the
8051 and the Z8 (including Super-8). This package includes a C
compiler, assembler, linker, librarian, and extensive printed
documentation. A simulator/source code debugger is available for an
additional $79.95.
Micro Computer Control Corporation
PO Box 275, 17 Model Ave., Hopewell, NJ 08525
(609)466-1751 Fax: (609)466-4116 BBS: (609)466-4117
Email: 73062...@compuserve.com

C isn't the only development system available (yeah, I know that's
hard to believe) - good solid Basic and Forth development systems are
also available. Refer to the appropriate FAQ for the microcontroller
that you are using for more information on free and commercial
development systems.

If the Microchip PIC is your game, then check out the Parallax tools
(available on their ftp and web sites). All Parallax software is
available free of charge to all takers! This includes PSIM (a PIC
simulator), PASM (an assembler for '5x parts), and PASMX (an
assembler for 'xx parts). These are the full commercial versions,
not hobbled in any way!

7) MICROCONTROLLER PROGRAMMING LANGUAGES

Just a bit of an introduction for the beginner.

7.1) Machine/Assembly language

Machine language is the program representation as the microcontroller
understands it. It is not easy for humans to read and is a common
cause of migraine headaches. Assembly language is a human-readable
form of machine language which makes it much easier for us flesh and
bone types to deal with. Each assembly language statement
corresponds to one machine language statement (not counting macros).

An assembly/machine language program is fast and small. This is
because you are in complete charge of what goes into the program. Of
course, if you write a slow, large, stupid program, then it will run
slowly, be too big, and be stupid. Assembly language (assembler)
can't correct stupidity - although sometimes I wish it could ;-).

If you are starting out learning about microcontrollers, it would be
worth your while first learning assembler. By programming in
assembler, you master the underlying architecture of the chip, which
is important if you intend to do anything significant with your
microcontroller.

7.2) Interpreters

An interpreter is a high level language translator that is closer to
natural language. The interpreter itself is a program that sits
resident in the microcontroller. It executes a program by reading
each language statement one at a time and then doing what the
statement says to do. The two most popular interpreters for
microcontrollers are BASIC and FORTH.

BASIC's popularity is due to its simplicity, readability, and of
course just about everyone has at least played with BASIC at one time
or another. One common compaint about [interpreted] BASIC is that it
is slow. Often this can be solved by using a different technique for
performing the desired task. Other times it is just the price paid
for using an interpreter.

FORTH has a very loyal following due to its speed (approaching that
of assembler language) and its incremental approach to building a
system from reusable parts. Many FORTH systems come with a host
system which turns your desktop computer into a development system.
FORTH can be quite difficult to write in (if you have no experience
with it) and is probably even harder to read. However, it is a very
useful and productive language for control systems and robotics, and
can be mastered in time.

The nicest thing about developing a system with an interpreter is
that you can build your program interactively. You first write a
small piece of code and then you can try it out immediately to see
how it works. When the results are satisfactory, you can then add
additional components until the final product is achieved.

7.3) Compilers

A compiler is a high level language translator that combines the
programming ease of an interpreter with greater speed. This is
accomplished by translating the program (on a host machine such as a
desktop PC) directly into machine language. The machine language
program is then burned onto an EPROM or downloaded directly to the
microcontroller. The microcontroller then executes the translated
program directly, without having to interpret first.

The most popular microcontroller compilers are C and BASIC. PL/M,
from Intel, also has some popular support due to that company's
extensive use of that language.

Due to both its popularity and its slow speed, it was only logical
that BASIC would appear as a compiled language. A few companies
supply a BASIC compiler for several of the more popular
microcontrollers. Execution speed is drastically increased over
interpreted BASIC since the microcontroller is freed from the task of
interpreting the statements as the program runs.

While interpreted Forth approaches (and sometimes surpasses) the
speed of many compilers, compiled Forth screams along. Today there
are many high performance optimizing native code Forth compilers, and
there are also lots of very cheap or free public domain Forths. Some
of them like Tom Almy's ForthCMP produces optimized native code with
less overhead and better performance than just about anything else
out there. Of course it still has compactness and more elegant
factoring of functionality than in most languages.

C is now the language of choice for the entire universe. C is used
on computers from the tiny microcontroller up to the largest Cray
supercomputer. Although a C program can be a bit tedious at times to
read (due to the terse programming style followed by many C
programmers), it is a powerful and flexible development tool.
Although a high level language, it also gives the developer access to
the underlying machine. There are several very good and cheap C
compilers available for the more popular microcontrollers. It is
widely used, available, supported, and produces fairly efficient code
(fast and compact).

7.4) Fuzzy Logic and Neural Networks

Fuzzy Logic and neural networks are two design methods that are
coming into favor in embedded systems. The two methods are very
different from each other, from conception to implementation.
However, the advantages and disadvantages of the two can complement
each other.

The advantage of neural networks is that it is possible to design
them without completely understanding the underlying logical rules by
which they operate. The neural network designer applies a set of
inputs to the network and "trains" it to produce the required output.
The inputs must represent the behavior of the system that is being
programmed, and the outputs should match the desired result within
some margin of error. If the network's output does not agree with
the desired result, the structure of the neural network is altered
until it does. After training it is assumed that the network will
also produce the desired output, or something close to it, when it is
presented with new and unknown data.

In contrast, a fuzzy-logic system can be precisely described. Before
a fuzzy control system is designed, its desired logical operation
must be analyzed and translated into fuzzy-logic rules. This is the
step where neural networks technology can be helpful to the
fuzzy-logic designer. The designer can first train a software neural
network to produce the desired output from a given set of inputs and
outputs and then use a software tool to extract the underlying rules
from the neural network. The extracted rules are translated into
fuzzy-logic rules.

Fuzzy logic is not a complete design solution. It supplements rather
than replaces traditional event control and PID (proportional,
integral, and derivate) control techniques. Fuzzy logic relies on
grade of membership and artifical intelligence techniques. It works
best when it is applied to non-linear systems with many inputs that
cannot be easily expressed in either mathematical equations used for
PID control or IF-THEN statements used for event control.

In an effort to change fuzzy logic from a "buzzword" (as it is in
most parts of the world) to a well established design method (as it
is in Japan), most manufacturers of microcontrollers have introduced
fuzzy logic software. Most software generates code for specific
microcontrollers, while other generates C code which can be compiled
for any microcontroller.

8) DEVELOPMENT TOOLS

Having a programming language is usually not enough to develop a
program for a microcontroller. Some way of debugging your program is
needed. I am only too painfully aware of this fact.

8.1) Simulators

A simulator runs your microcontroller program on a host machine (such
as your PC). You can step through the code to see exactly what is
happening as the program runs. Contents of registers or variables
can be altered to change the way the program runs. Eliminates (or at
least delays) the erase/burn/program EPROM cycle common in
microcontroller program development. You can work out ideas or learn
about microcontrollers by experimenting with small code fragments and
watching on the screen what happens. A simulator can't support real
interrupts or devices, and usually runs much slower than the real
device the program is intended for.

Some manufacturers have a cross between a software simulator and the
hardware emulator - a hardware simulator. This is a piece of
equipment that plugs into your target, and the pins will toggle and
react like they should - just MUCH slower. Cost of a device like
this is only about $100. Two such boards by National Semiconductor
and Philips are detailed in section 6.2.

8.2) Resident Debuggers

A resident debugger runs your program on the microcontroller itself,
while showing the progress on your host machine (such as a PC). Has
many of the same advantages as simulator above, with the additional
benefit of seeing how the program runs on the real target machine. A
resident debugger needs to "steal" some resources from the target
machine, including: a communications port to communicate with the
host, an interrupt to handle single stepping, and a certain amount of
memory for the resident part (on the target) of the debugger.

8.3) Emulators

If you've got the money, this is the equipment you want to develop
your system with (yeah, that's right, a preposition at the end of a
sentence!). A [usually] expensive piece of hardware that even for
the cheaper versions will run you at least $700. An emulator is a
sophisticated device that pretends that it is the microprocessor
itself, while at the same time capturing information. It provides
full and total control over your target, while at the same time not
requiring any resources from the target. The emulator can either be
a stand alone device with its own display, or it can be interface to
a PC.

8.4) Good Stereo System

This is the most important tool for the microcontroller developer, or
for any computer system developer for that matter. Don't expect to
get anywhere unless you have the proper music playing in the
background(?) at the proper volume. I find that I do my best work
with the Rolling Stones (especially Goats Head Soup) or Clapton
(especially early stuff like Cream - Disraeli Gears is a killer
album!). The volume must be set to cause excrutiating pain to be
most effective. Trust me on this ;-).

Tom Mornini of Parallax reports: "Johnny Cash also has a certain
effectiveness, as well as the Beatles, Aerosmith, and Rush! 60's
rock and British invasion bands in particular seem to have a
particularly productive effect."

This would be an interesting topic for an in-depth study.
Particularly intriguing, is if certain types of music work better
with specific [families of] processors. Another question in need of
study would be if it's really true that the smaller the chip (in
bits), the louder the music needs to be.

9) FINDING OUT MORE ABOUT MICROCONTROLLERS

If you are interested in learning more about microcontrollers, there
are many fine sources of information. You have your choice of
printed media (books, periodicals, informative graffiti) or
interactive (right here on the Internet, or BBSs).

9.1) Books

8-bit Microcontroller Instruction Set Performance
- Digitial Systems Consulting / June 1994
- compares Motorola's M68HC05, Intel's 80x51,
Microchip's PIC16C5x, and National's COP8
- lit number 630008
- (800)272-9959 call this number for copies

The 16 bit 8096: Programming, Interfacing, Applications
- Ron Katz and Howard Boyet
- Microprocessor Training Inc
14 East 8th Street, New York, NY 10003
212-473-4947
- Library of Congress Catalog card number: 85-61954
- According to William Chernoff: "The book is pretty good -
mostly software examples. The one hardware thing I looked
closely at was wrong - a schematic error. Oh well."

The 68hc11 Microcontroller
- Joseph D. Greenfield (at R.I.T.)
- Saunders College Publishing, (Harcourt Brace Jovanovich)
- 1992
- ISBN 0-03-051588-2
- A number of the sections make use of the Buffalo monitor.
This could be useful if you are using the Motorola Trainer EVB.

The 8051 Family of Microcontrollers
-Richard H. Barnett
-Prentice-Hall, 1995 (yeah, that's right, 1995!)
-ISBN 0-02-306281-9

8051 Interfacing and Applications
- Applied Logic Engineering
13008 93rd Place North, Maple Grove, MN 55369
- (612)494-3704

The 8051 Microcontroller
- I. Scott MacKenzie
- Prentice Hall
- 2nd edition, 1995
- ISBN 0-02-373660-7
- includes schematics for a single-board computer,
assembly-language source code for a monitor program, and
interfaces to a keypad, LEDs, and loudspeaker

The 8051 Microcontroller
- James W. Stewart
- Regents/Prentice-Hall, 1993
- $27.50, 273 pages
- includes many interfacing examples (switches, solenoids,
relays, shaft encoders, displays, motors, and A/D converters)
and a chapter on top-down design method

The 8051 Microcontroller: Architecture, Programming and Applications
- Kenneth J. Ayala
- 241 pages, soft cover
- 5.25" diskette with assembler and simulator
- ISBN 0-314-77278-2, Dewey 004.165-dc20
- West Publishing Company
P.O. Box 64526, St. Paul, MN 55164
(800)328-9352
- see review in next section

The Art of Programming Embedded Systems
- Jack G. Ganssle
- 1992, 279pp, $55.00
- ISBN: 0-12-274880-0
- CONTENTS: Introduction, Initial Considerations. Elegant
Structures. Designs for Debugging. Design for Test. Memory
Management. Approximations. Interrupt Mamangement. Real-Time
Operating Systems. Signal Sampling and Smoothing. A Final
Perspective. Appendixes: Magazines, File Format. Serial
Communications. Bibliography. Index.

Assembly Language Programming (for the MCS-51 family)
- F. A. Lyn
- L. S. Electronic Systems Design

Basic-52 Programmer's Guide
- Systronix, Inc. (they also sell a Basic compiler)
- address above

Beginner's Guide
- Suncoast Technologies

A Beginners Guide to the Microchip PIC
- Nigel Gardner
- Character Press, Ltd. (UK)
- ISBN 1 899013 00 8
- software (on floppy) and hardware guide, debugging techniques
- suitably titled, for those with no previous microcontroller
experience
- 19.95 UK Pounds

The PIC Source Book:
- assembly language source code on diskette
- $39
- Scott Edwards Electronics
964 Cactus Wren Lane, Sierra Vista, AZ 85635
(602)459-4802 Fax: (602)459-0623
72037...@compuserve.com

C and the 8051
- Thomas W. Schultz
- Prentice Hall
- ISBN 0-13-753815-4

Data Acquisition and Process Control with the M68HC11 Microcontroller
- Frederick Driscoll, Robert Coughlin, Robert Villanucci of
Wentworth Institute of Technology.
- Macmillan Publishing Company
- 1994
- ISBN 0-02-33055-X
- Several Chapters on the 68HC11, instructions, and EVB;
chapters on interfacing Analog and Digital signals to the
68HC11; example applications of interfaces to temperature,
load cell, pressure and thermocouple sensors.
- a good companion to Motorola's "pink" books

Data book / Handbook / Users' Guide
- Advanced Micro Devices
- Dallas (User's guide for the DS5000)
- Intel
- Siemens

Design with Microcontrollers
- John B. Peatman
- ISBN 0-07-049238-7
- This book is on a more advanced level. Uses both the 68hc11
and Intel 8096 as example systems.
- Used for a very popular course on microcontroller design at
Georgia Tech.

Embedded Controller Forth for the 8051 Family
- Academic Press
- William H. Payne
- uses a Forth development system available on the Internet

Embedded Controllers Databook 1992 Edition
- National Semiconductor Corporation
- literature number: 400049
- (800)272-9959 call this number for for copies

Embedded Systems Programming in C and Assembler
- John Forrest Brown
- Van Nostrand Reinhold, 1994
- 304 pages, $49.95
- ISBN 0-442-01817-7
- covers Motorola and Intel processors
- includes diskette with code from the book
- book review in Dr. Dobb's Journal, November 1994, page 121

Experimenter's guide
- Rigel Corporation

Introduction to Microcontroller Design, Based on the 8051 family of
Processors
- Business Data Computers
P.O. Box 1549, Chester, CA 96020

Mc68hc11 An Introduction
- Han-Way Huang
- Software and Hardware Interfacing, Applications using the
EVB from Motorola.
- West Publishing Company
- ISBN 0-314-06735-3

M68hc11 Reference Manual
- Motorola - literature reference M68HC11RM/AD
- This document is the "bible" of the 6811 and is a must-have
for any serious 6811 programmer.

MC68hc811E2 Programming Reference Guide
- Motorola - literature reference M68HC811E2RG
- A pocket-sized guide to the version of the 6811 used on the
Mini Board

The Microcontroller Idea Book
- Jan Axelson (of Microcomputer Journal fame)
- features the 8052-BASIC microcontroller
- hands-on guide with complete plans (schematics, design theory,
program listings, construction details, etc)
- explains how to use sensors, relays, displays, clock/calendars,
keypads, wireless links, and more
- 1994, 273 pages, $31.95 + shipping
- Lakeview Research, 2209 Winnebago St., Madison, WI 53704
(608)241-5824 Internet: 71163...@compuserve.com
- contact the author at jan...@aol.com

Microcomputer Engineering
- Gene H. Miller
- Prentice Hall, Englewood Cliffs, NJ 07632
- 1993
- ISBN 0-13-584475-4
- Explains the basics. Many clear and concise assembly language
example programs.
- Written to be used with the Motorola Trainer (EVB).

Microcontroller Technology, The 68hc11
- Peter Spasov
- Prentice Hall
- ISBN 0-13-583568-2

Microcontrollers: Architecture, Implementation, and Programming
- Kenneth Hintz and Daniel Tabak
- McGraw-Hill Inc. 1992
- ISBN 0-07-028977-8

Microprocessor 1995
- Jack Quinn, Micrologic Research
- Integrated Circuit Engineering Corporation
15022 North 75th St., Scottsdale, AZ 85260-2476
(602)998-9780 Fax: (602)9481925
- comprehensive study of the microprocessor industry and market,
current status, trends, and developments
- $1495
- Microprocessor 1996 due out in November

PIC 16Cxx Development Tools instructions manuals
- Parallax, Inc.
- Instruction manual for the Parallax PIC assemblers
- Instruction manual for the Parallax Software Simulator
- Instruction manual for the Parallax PIC programmer hardware
- Details the Parallax PIC instruction set

PIC 16Cxx Applications Handbook
- Parallax, Inc.
- Contains condensed data sheets for '5x, '64, '71, and '84
controllers
- Contains 14 application notes showing circuits and code for
common projects using the PIC series of microcontrollers.

Easy PIC'n, A Beginner's Guide to Using PIC16/17 Microcontrollers"
- ISBN 0-9654l62-0-8
- intended to ease the beginner toward understanding and
application of the PIC16/17 line of microcontrollers from
microchip Technology Inc. For the hobbyist or engineer for
self study or as a text for a college engineering course in the
application of microcontrollers.
- examples of assembly language programs
- in-depth coverage of program writing using flow charts
- the approach is hands-on with lots of examples, all of which
may be demonstrated using a very simple demo board (a project)
described in the beginning of the book
- For more information, contact the author:
David Benson, Author (Easy PIC'n)
Owner, Square 1 Electronics
squa...@zapcom.net
(707)279-8881 Fax: (707)279-8883

Posix.4: Programming for the Real World
- Bill O. Gallmeister
- O'Reilly and Associates, 1995
- ISBN 1-56592-074-0
- Part I of the book describes the Posix standard (what it is,
what it isn't, and what it's for), and explains the principles
of real time programming (tasking, messages, scheduling, I/O,
and performance) and why Unix isn't fit for real-time
programming. Part II is a reference on the Posix functions and
header files. Part III contains much of the code for the
exercises in the book.

Programmer's Guide to the 1802
- Tom Swan
- Hayden Book Company, Inc., 1981
- ISBN 0-8104-5183-2
- good introduction to assembly language progamming and an
thorough tutorial on the 1802

Programming Microcontrollers in C
- Ted Van Sickle
- HighText Publications, 1994
- 394 pages, $29.95
- ISBN 1-878707-14-0
- thorough tutorial on C programming, covers aspects of C
programming specific to embedded systems
- covers the Motorola line of microcontrollers (small to large)
- book review in Dr. Dobb's Journal, November 1994, page 121

The Real-Time Kernel
- Jean Labrosse
- R&D Publications, Inc.
Suite 200 1601 W 23rd St., Lawrence, KS 66046
- (913)841-1631 Fax: (913)841-2624
- Based on the article "A Portable Real Time Kernel in C"
in Embedded Systems Programming (Part 1: vol 5 no 5
May 1992, Part 2: vol 5 no 6 June 1992)
- originally written for the Intel 186 but ported to HC11
source code for UCOS11

Single- and Multiple-Chip Microcomputer Interfacing
- G.J. Lipovski
- Copyright 1988
- 478 pages
- ISBN 0-13-810557-X (Prentice-Hall Edition)
ISBN 0-13-810573-1 (Motorola Edition)
- Based around the 68HC11 it covers both hardware and
software at undergraduate level, but the emphasis is on
interfacing.
- Chapter titles:
1 Microcomputer Architecture
2 Programming Microprocessors
3 Bus Hardware and Signals
4 Parallel and Serial I/O
5 Interrupts and Alternatives
6 Analog Interfacing
7 Counters and Timers
8 Communications Systems
9 Storage and Display Systems

Single- and Multiple- Chip Microcomputer Interfacing (Lab Manual)
- Peter Song and G. Jack Lipovski
- Prentice-Hall, 1988
- ISBN 0-13-811605-9
- Support for the above book. Examples based around the Motorola
EVB and the BUFFALO monitor or the EVBU (or 3-chip micro) and
PC-Bug11.

User Manual for the CDP1802 COSMAC Microprocessor
- RCA, 1977
- contains useful hardware and software techniques

9.2) Data and Reference Books

Motorola
- M68hc11 Reference Manual, ref # M68HC11RM/AD
this document is the "bible" of the 6811 and is a must-have
for any serious 6811 programmer
contact Motorola at 800-521-6274 (in the U.S.) to get a free
copy of this manual
- MC68hc811E2 Programming Reference Guide, ref # M68HC811E2RG
a pocket-sized guide to the version of the 6811 used on the
Mini Board, "ownership of this handy reference is proof of
being a true 6811 nerd" - by Fred Martin

National Semiconductor - (800)272-9959 for copies
- COP8 Databook, ref # 400007
- COP8 Selection Guide, ref # 630006
- COP8 Designers Information Kit, ref # 6300007-005
contains: - COP8 Databook (1994 Edition)
- COP8 Selection Guide (1994 Edition)
- Independent 8-bit Instruction Set Analysis
- Independently prepared software analysis of
National's COP8, Motorola's M68Hc05, Intel's
80X51, and Microchip's PIC16C5X
- Utility and Overview Disks
- Self-lead overview on COP8, includes electronic
selection guide and sample application code
- COP8 Utility Disk, Mac ref # 6300000, Windows ref # 630001
typical microcontroller applications and sample code
available by ftp nscmicro.nsc.com in/pub/COP8
- COP8 Overview Disk, Mac ref # 630004, Windows ref # 630005
self-lead COP8 overview, shows product features/benifits
and includes a electronic selection guide (2 disks)
available by ftp nscmicro.nsc.com in /pub/COP8

9.3) Periodicals

Various magazines and journals (journals seems to be THE popular name
for magazines these days) provide articles from time to time on
microcontrollers. If you are just starting out learning, pick those
magazines that feature construction articles.

The Computer Applications Journal (Circuit Cellar Ink)
- programming and construction articles
- POB 7694, Riverton, NJ 08077-8784
- Fax: (203)872-2204
- Voice orders: (609) 786-0409
- On-line orders (BBS): (203) 871-1988
- Email orders: ken.da...@circellar.com
- $21.95, $31.95 surface Canada and Mexico,
$49.95 air all other countries

Computer Design
- industry announcements and trends
- One Technology Park Drive, P.O. Box 990, Westford, MA 01886
- (508)692-0700

The Computer Journal
- programming and construction articles, specializing in old
computers (S-100, CP/M, TRS-80, Xerox, Adam, etc)
- P.O. Box 3900, Citrus Heights, CA 95611-3900
- (800)424-8825 or (916) 722-4970 FAX: (916) 722-7480
- BBS: (916) 722-5799
- WWW: http://www.psyber.com/~tcj
- Email: t...@psyber.com
Dave Baldwin: dib...@netcom.com
Bill Kibler: kib...@psyber.com
- USENET newsgroup alt.tcj

Control Engineering
- industry outlook on control, instrumentation, and automation
systems
- Cahners Publishing
- Circulation:
8773 S. Ridgeway Blvd., Highlands Ranch, CO 80126-2329
(303)470-4000
- Editorial/Executive Offices:
1350 E. Touhy Ave, P.O. Box 5080, Des Plaines, IL 60017-5080
(708)635-8800

Dr. Dobbs Journal
- programming articles, concepts, and designs
- 411 Borel Ave., San Mateo, CA 94402
- (415)358-9500

Electronic Engineering Times
- industry announcements and trends
- 500-B Bi-County Boulevard, Farmingdale, NY 11735
- (516)293-3000

Electronics Now
- construction articles
- Box 55115, Boulder, CO 80321-5115
- $19.97 one year

Elektor Electronics
- programming and construction articles
- World Wide Subscription Service Ltd
Unit 4, Gibbs Reed Farm, Pashley Road
Ticehurst TN5 7HE, England
- 27 UK pounds
or
- Old Colony Sound Lab, P.O. Box 243, Peterborough, NH 03458
- Tel. (603) 924-6371, 924-6526
- Fax: (603) 924-9467
- $57 USA and Canada per year

Embedded Systems Programming
- programming and systems design articles
- Miller Freeman Publications
- 500 Howard St., San Francisco, CA 94105
- Miller Freeman: (415)905-2200
Embedded Systems Programming phone: (800)829-5537

Forth Dimensions
- monthly magazine on Forth
- Forth Interest Group, P.O. Box 2154, Oakland, California 94621
- (510)893-6784 Fax: (510)535-1295
- Email: john...@aol.com
- Forth Interest Group home page:
http://taygeta.oc.nps.navy.mil/fig_home.html

Inquisitor Magazine
- If you're the type that watched Gilligan's Island for its
socio-political insights, then you'll love a new 'zine that
just crossed my desk - Inquisitor Magazine. It's general
philosophy seems to be ... well, it seems to be ... uh, yeah!
Technical in nature, bizarre, tongue in cheek, eclectic,
electric, did I mention bizarre(?), and lots of fun. Worth
looking at if you like the out of the ordinary. The moving
force behind this magazine is Daniel Drennan, who seems to have
suffered from an overdose of radiation from his computer
monitor ;-).
- Dan is offering issue 1 of Inquisitor for free except for
postage ($1.00 in the United States; $2.00 for Canada and
overseas surface mail; and $3.00 for overseas airmail). This
issue contains plans, schematics, and troubleshooting tips for
putting together a 8052-based microcontroller. If you're
thinking of putting together an 8051 system, you might want to
check this out.
- Planetarium Station, P.O.Box 132
New York, NY 10024-0132
- (212)595-8370
- Email: inqui...@echonyc.com
- $16 per year (4 issues)

Microcomputer Journal (formerly Computer Craft)
- programming and construction articles
- 76 N. Broadway, Hicksville, NY 11801
- $18.95 one year, foreign $23.00, foreign air mail $76.00

Midnight Engineering
- 1700 Washington Ave., Rocky Road, CO 81067
- (719)254-4553

MW Media - Product Directories
- Motorola Microcontroller Tools Directory
('94 edition out in 3 weeks)
- Motorola 68K Source ('94 edition available now)
- Intel Development Tools Handbook ('95 edition just beginning)
(survey of commercial development tools for the 8051, 8096,
and 80186 lines of Intel microprocessors)
- Embedded Intel 386 Directory (released in Aug '94)
- Intel 486/Pentium directory (forthcoming in '95)
- 8051 Product Directory ('94 edition out in 4 weeks)
(survey of various 8051 products)
- Hitachi Microcontroller Development Tools Directory
(out in '95)
- AMD FusionE86 Directory (out in '95)
(186,386,486)
- AMD 29K Directory (pending in '95)
- Low Power Product Directory (out in '95)
(3.3. volts and lower)
- DSP Directory (released in May '94)
- Multimedia CD (hopefully out in '95)
- These documents could very well be a "must" if you're into
serious development using any of these chips. If you are
"just" a hobbyist, see how the "other half" lives.
- FREE to qualified developers
- MW Media
- Fairmont Plaza, 50 W. San Fernando, #675, San Jose, CA 95113
- (408)288-4721 (408)286-4200 FAX: (408)288-4728

Nuts & Volts Magazine
- A National Publication for the Buying and Selling of
Electronic Equipment
- 430 Princeland Court, Corona, CA 91719
- Mailed third class, USA only: $17.00 one year
$31.00 two years
- Mailed first class, one year only: $34.00-USA
$35.00-Canada/Mexico
- Foreign/Air Mail - $70.00; Foreign/Surface - $39.00
- (800)783-4624
- Email: 74262...@Compuserve.com

9.4) USENET newsgroups

Various newsgroups frequently have discussions or information on
various microcontrollers. Among some of the more useful (especially
the first 3 newsgroups):

comp.robotics
Microcontrollers figure heavily in robotics projects. You will
find a lot of information about the subject in this newsgroup.
Even if you aren't building a robot, check this newsgroup out.
Lots of 68hc11 activity, too.

comp.arch.embedded (great!)
This is a great newsgroup. Well targeted discussions on aspects
of embedded systems and microcontrollers.

sci.electronics (lots of traffic, but good)
alt.comp.hardware.homebuilt (too much nonsense on PCs)
Some good places to find [mostly technical] discussions on
microcontroller use and implementation. Most of the participants
are crazy about "rolling their own", and are eager to share their
knowledge. These groups aren't well focused, and many subjects
that aren't relevant to embedded control are covered here.

comp.realtime
Since embedded systems (controllers/processors) are almost always
used in real time applications, this group could prove to be
useful. Occasional discussions about various microcontroller
topics.

comp.os.qnx
QNX is the leading realtime OS for PCs in terms of market share.
It is used in high-end embedded systems (16 and 32 bit); set-top
boxes, automotive industry, banking, telecomms, etc.

comp.sys.m68k
The full line of Motorola 68000 microprocessors is discussed in
this newsgroup, including the very powerful and advanced embedded
processors and microcontrollers based on this family.

comp.sys.6809
This newsgroup covers an old-time favorite, the 6809
microprocessor, which is commonly used for control applications.
Motorola 8 bit microprocessors and microcontrollers (6805, 6811,
etc.) are also discussed in this newsgroup.

comp.sys.intel
Mostly trends and development are discussed in this newsgroup.
From time to time you will find a discussion on some technical
problem or feature. This newsgroup is usually fairly useless.
For a while the participants spent most of their time whining
about the Pentium bug. Now they're all moaning about Microsoft,
PowerPCs, and everything else BUT Intel parts. I propose changing
the name of this group to alt.crybabies.boo.hoo.hoo.

comp.lang.misc
Sometimes questions or discussions on different microcontroller
topics pop up here. I guess it's the ".misc" that attracts these
questions.

comp.ai.fuzzy
Fuzzy logic is rapidly becoming an increasingly important aspect
of [embedded] control systems. This group might very well become
an important forum for those involved in developing control
systems.

comp.dsp
Discussions on Digital Signal Processsing

comp.sys.ti
Texas Instruments products discussed here

sci.engr.control
This forum is for the discussion of control and embedded systems.

sci.engr.semiconductors

9.5) Internet sources of information on specific microcontrollers

If you are interested in finding sources of information on a specific
microcontroller, check out the really fine FAQs ;-) that have been
compiled for the more popular microcontrollers.

Subject: PIC microcontrollers
Newsgroups: <no longer posted to newsgroups>
Web page: http://digiserve.com/takdesign
Maintainer: Tom Kellett
Email: T...@takdsign.demon.co.uk

Subject: 8051 microcontrollers
Newsgroups: comp.sys.intel
comp.realtime
comp.robotics
comp.lang.forth
sci.electronics
Archive: rtfm.mit.edu : <plus all mirror sites>
/pub/usenet/comp.answers/microcontroller-faq/8051
/pub/usenet/sci.answers/microcontroller-faq/8051
/pub/usenet/news.answers/microcontroller-faq/8051
Maintainer: Russ Hersch
Email: ru...@shani.net

Subject: 68hc11 microcontrollers
Newsgroups: comp.realtime
comp.robotics
sci.electronics
Archive: rtfm.mit.edu : <plus all mirror sites>
/pub/usenet/comp.answers/microcontroller-faq/68hc11
/pub/usenet/sci.answers/microcontroller-faq/68hc11
/pub/usenet/news.answers/microcontroller-faq/68hc11
Maintainer: Robert Boys - Ontario, Canada
Email: rb...@best.com
Russ Hersch (maintainer emeritus :-)

Subject: Motorola 68K microprocessor line
Newsgroups: comp.sys.m68k
Archive: ftp.ee.ualberta.ca : pub/motorola/general
ftp.luth.se : /pub/misc/motorola/faq
file name of archive is m68kfaq?.zip (? is version)
Comments: - also includes information on the 683xxx and 68hc16
- without a doubt, one of the finest FAQs ever written
(well, of course Bob paid me to say this ;-)
Maintainer: Robert Boys - Ontario, Canada
Email: rb...@best.com

Subject: ST6 microcontroller FAQ
Newsgroups: sci.electronics
comp.arch.embedded
comp.robotics
comp.realtime
Maintainer: Emilio Caggiano - cagg...@vm.csata.it
Jerry van Kampen - ersi...@er.ele.tue.nl
Leonhard Schneider - ub...@rz.uni-karlsruhe.de

Several other FAQs have been compiled that address various aspects of
microcontroller design and implementation.

Subject: I2C protocol
Newsgroups: sci.electronics
alt.hardware.homebuilt
comp.robotics
comp.protocols.misc.
Comments: The I2C bus is a simple 2 wire serial interface
developed by Philips. A number of 8051 variants as
well as several peripherals include I2C support.
Maintainer: Vincent Himpe
Email: Vincen...@ping.be

Subject: Robotics
Newsgroups: comp.robotics
Maintainer: Kevin Dowling
(412)268-8830
Email: ni...@ri.cmu.edu
Smail: Carnegie Mellon University
The Robotics Institute
Pittsburgh, PA 15213

Subject: Electronics
Newsgroups: sci.electronics
Comments: There are a number of FAQs available in this newsgroup
on various subjects. Among some of the subjects covered
are: LCDs, stepper motors, suppliers, etc.

Subject: Real-time
Newsgroups: comp.realtime, comp.answers, news.answers
Archive: rtfm.mit.edu : pub/usenet/comp.realtime
Maintainer: Mark Linimon
Lonesome Dove Computing Services
Roanoke, Virginia
Email: lin...@nominil.lonesome.com.

Subject: Neural Networks
Newsgroups: comp.ai.neural-nets,comp.answers,news.answers
Archive: rtfm.mit.edu : pub/usenet/neural-net-faq
Maintainer: Lutz Prechelt
Email: prec...@ira.uka.de

Subject: Fuzzy Logic
Newsgroups: comp.ai.fuzzy,comp.answers,news.answers
Archive: rtfm.mit.edu : pub/usenet/fuzzy-logic/
Maintainer: Mark Kantrowitz
Email: mka...@cs.cmu.edu

Subject: alt.comp.hardware.homebuilt FAQ
Newsgroups: alt.comp.hardware.homebuilt
Comments: This file contains frequently asked questions (FAQ) and
general information pertaining to the newsgroup
alt.comp.hardware.homebuilt.
Maintainer: Mark Sokos (mso...@gl.umbc.edu)

10) MICROCONTROLLER FREE SOFTWARE SOURCES

This section includes descriptions and references to free
microcontroller software. FTP sites and BBSs contain many quality
packages and code samples for free. For heavy duty use, you might
prefer the many commercial packages that are available. With the
public domain (or free) stuff, you're usually on your own. The
commercial packages usually provide extensive documentation and
support.

If you are looking for commercial software for the 8051, 68hc11, or
PIC, then check out the FAQs on these microcontrollers for details on
what is available.

10.1) FTP sites

The following is a list of the anonymous ftp sites that have source
code and programming languages for various microcontrollers. There
are many others that are not listed here that contains bits and
pieces. Usually you can find them using Archie and searching for
variations on the name of the microntroller you are looking for.

ftp.pppl.gov (formerly lyman.pppl.gov)
- this is a great source of 8051 stuff
/pub/8051
/pub/incoming - check this out for new untested/unsorted items

ftp.mcc.ac.uk
- this is a new 8051 ftp site

ftp.intel.com
- good source of stuff the MCS-51 and MCS-96 families
/pub/mcs51 - various development tools and sample code for the
MCS-51 family
/pub/mcs96 - various development tools and sample code for the
MCS-96 family

nctuccca.edu.tw
- mirror of ftp.intel.com
/vendors/Intel

freeware.aus.sps.mot.com (Motorola)
- the ftp site version of the freeware BBS
- lots of free software for the HC05, HC08, HC11, HC16, 680x0,
683xx, and PowerPC
- also see the Web pages in the next section

nscmicro.nsc.com
- the authoratative source for COP8 infomation
/pub/COP8 - various develepment tools and sample code for the
COP8 family including most application notes

ftp.zilker.net
- /pub/philips
- Philips "mini ftp site" set up by Phil Wood of Philips
- lots of 8051 code and programming tools from their BBS

Philips...@InetBSystems.us.com
- send Email message with the word "help" in the subject line to
learn how to access the archive

ftp.ee.ualberta.ca
- Circuit Cookbook
- HUGE archive of all sorts of stuff on the 68hc11 (lots of other
good stuff too!)
- you'll have fun mucking around this ftp site, there's piles of
stuff here
/pub/cookbook
/pub/motorola
/pub/motorola/68hc11
/pub/motorola/mcu11

cherupakha.media.mit.edu (cher.media.mit.edu)
- HUMONGOUS archive of all sorts of stuff on the 68hc11 including
the 6.270 robotics project, Mini Board, F1 board, and more
(lots of other good stuff too!)
- you'll lose yourself rooting around this ftp site, there's
piles of stuff here (assemblers, tools, C compilers, plans and
schematics, and many other items)
/pub/projects - tools, docs, schematics, etc. for the MIT 6.270
robotics project using a 68hc11-based development system
/pub/6811 - software, schematics, etc. for the 68hc11-based F1
board
/pub/incoming - various unsorted or new items
/pub/miniboard - software, docs, schematics, etc. for the 3"x2",
68hc11-based Mini Board controller

ftp.funet.fi (nic.funet.fi)
- this is a good source for various microcontrollers
/pub/microprocs/ (subdirectories include: 1802, 6805, 8048,
8051, 8096, PIC and many other microprocessors)

ftp.sics.se
- many assemblers, utilities, and application notes for the PIC
- Microchip BBS mirror
- ftp site of Memec Scandinavia, Microchip's Swedish agent.
/pub/mchipsoft

ernie.uvic.ca
- files provided by local Motorola representative
/pub (subdirectories include: ibm, dsp96k, dsp56100, dsp56k,
dsptools, develop, mac, mcu302, mcu332, mcu11, pgmr, mcu16,
mcu, market, qa, general, m68k, evm, dsp)

wpi.wpi.edu
- basic stamp information
- PIC "C" compiler
/stamp

ftp.std.com
/vendors/microchip/

ftp.luth.se
/pub/misc/microchip - PIC information
/pub/misc/microchip/stamp/mirror - mirror of wpi.wpi.edu
/pub/languages/assembler - various freeware assemblers

ti.com
read the 00readme file first or you'll be lost

asterix.inescn.pt - FORTH archive
/pub/forth

hpcsos.col.hp.com
/mirrors/.hpib0/forth/8051 (mirror of asterix Forth archive)
/mirrors/.hpib0/forth/eForth
/misc/ns32k/beowulf

ftp.netcom.com
/pub/imagecft - prerelease version of ImageCraft C for 68hc11

in...@circellar.com - Email (not ftp)
- send Email to get information file on services available
- all Circuit Cellar INK and BYTE related files available

ftp.ultranet.com
/biz/mchip - PIC information
- also see the Web page: http://www.ultranet.com/biz/mchip

ftp.mrc-bbc.ox.ac.uk
/pub/microchip

ftp.oak.oakland.edu
- has information and software for a wide range of
microprocessors and microcontrollers

ftp.uni-erlangen.de
- information on PIC
/mounts/epix/public/pub/Multimedia/VideoCrypt/
microcontroller/microchip.bbs

ftp.armory.com (Steve Walz)
- /pub/user/rstevew/8051
- /pub/user/rstevew/TB8051
- /pub/user/rstevew/incoming

ftp.cygnus.com (Jeff Fox)
- source of information and software on the MuP21 Forth
microcontroller
/pub/forth - MUP21FTP.ZIP includes a software simulator for
the MuP21 and and the upcoming F21.
also see the Web page: http://www.dnai.com/~jfox

ftp.best.com
/pub/cera
ftp.netcom.com
/pub/ce/cera
- embedded systems FTP archive

ftp.parallaxinc.com
/pub
- ftp site of Parallax
"Cool PIC development tools & the BASIC Stamp"

ftp.std.com - Minds-Online ftp site
/customers2/nonprofits/minds-online
- Chock full of compilers, assemblers, code, articles, fuzzy
logic, and much more.

evans.ee.adfa.oz.au
/mirrors/tms340
- support for Texas Instruments parts

ftp.ti.com
/mirrors/tms320bbs
- mirror of the contents of Texas Instruments BBS

ftp://iglou.com/members/ITU
- Microchip PIC and embedded systems

ftp://ieee.cas.uc.edu
- electronics archive

10.2) Web pages

Advanced Micro Devices, Embedded Processor Division home page
- http://www.amd.com/html/products/EPD/EPD.html
- covers both the 29K and E86 embedded processor lines

AM Research, the Embedded Control Experts
- http://www.amresearch.com

Automation and Process Control
- http://www.ba-karlsruhe.de/automation/home.html

Brian Brown's 8051 web page
- http://www.cit.ac.nz/smac/cbt/hwsys/i8051/default.htm
- contains Brian Brown's 8051 course
- lots of other good stuff

Cera Research web pages
- Electronic Engineers' Toolbox (home page)
http://www.cera2.com/ebox.htm
- MCU/MPU resources
http://www.cera2.com/micro.htm
- Navi-GATOR (embedded dev. tools and chip-specific)
http://www.cera2.com/gator.htm

Chip Directory and Chip Manufacturers (Jaap van Ganswijk)
- http://www.hitex.com/chipdir (USA, California)
- http://www.civil.mtu.edu/chipdir (USA, Michigan)
- http://www.leg.ufrj.br/chipdir (Brasil)
- http://www.xs4all.nl/~ganswijk/chipdir (The Netherlands)
- http://bbs.cc.uniud.it/chipdir (Italy)

Chipmakers web page (Gary Creager)
- http://www.scruznet.com/~gcreager/hello5.htm
- well over 200 semiconductor manufacturers web pages

Circuit Cellar Ink
- http://www.circellar.com

Dallas Semiconductor
- http://www.dalsemi.com

Electronic Laboratory of the DAEC Department of Meudon
- http://formper1.obspm.fr
- electronics, embedded systems, FPGA, microncontrollers in
astronomy projects

Embedded Systems Information (Cera Research)
- http://www.cera.com

Forth Interest Group home page
- http://taygeta.oc.nps.navy.mil/fig_home.html

French Forth web site
- http://ourworld.compuserve.com/homepages/mp7
maintained by Marc Petremann:
17, allee de la Noiseraie
F - 93160 NOISY LE GRAND
Email: 10064...@compuserve.com
- http://ourworld.compuserve.com/homepages/bioforth
maintained by Gerard SOULA

Gernsback Web page (Electronics Now, Popular Electronics)
- http://www.gernsback.com
- current issue information, recent article related files, FTP
site, subscription information

Gregory Pugh's homepage
- http://sleepy.anest.ufl.edu/~glp/8051.html

High Tech Horizon
- http://www.hth.com
- This web page is in Swedish, but the files are available to all
in the "Hardware Hackers Filelibrary" at the bottom of the
Web-page.
- High Tech Horizon, Asbogatan 29 C, S-262 51 Angelholm, SWEDEN
+46 431 41 00 88 Fax: +46 431 41 00 88
Email: in...@hth.com

ITU Technologies (ITU...@aol.com)
- Microchip PIC and embedded systems
- http://www.iglou.com/ITU

Ken Tindell's CAN web pag
- http://www.nrtt.demon.co.uk/can.html
- Source code to drive the Intel 82527 CAN controller is
available: just send e-mail to in...@nrtt.demon.co.uk, with
"Request Intel 82527 drivers" (without the quotes) in the
subject line.

Microchip PIC
- http://www.ultranet.com/biz/mchip

Motorola's semiconductor WWW page
- http://motserv.indirect.com
- on-line searchable Master Selection Guide and OEM Price Book
- 'MFax' service to request all kinds of data sheets
- a bunch of other cool stuff

Motorola's microcontroller WWW page
- http://freeware.aus.sps.mot.com/index.html
- the WWW version of the freeware BBS
- lots of free software for the HC05, HC08, HC11, HC16, 680x0,
683xx, and PowerPC

MuP21 Forth microcontroller
- http://www.dnai.com/~jfox
- information and software on the MuP21 Forth uC

Parallax Inc. web page
- http://www.parallaxinc.com
- "Cool PIC development tools & the BASIC Stamp"

POLIS web site
- POLIS offers an integrated interactive environment for
specification, co-simulation, formal verification, and
synthesis of embedded systems implemented as a mix of hardware
and software components.
- http://www-cad.eecs.berkeley.edu/Respep/Research/hsc/abstract.html
Most of the information about POLIS, including pointers to
source and object code (for various CPUs and OSes) is available
at this WEB site
- If you are interested, but do not have WEB access, contact
them at: po...@ic.eecs.berkeley.edu.

QNX realtime website
- http://www.qnx.com

Scrumpel 68hc11 web page
- http://www.stack.urc.tue.nl/~hcc6811

Texas Instruments
- http://www.ti.com/sc/docs/micro/home.htm

Zorin
- http://www.eskimo.com/~zchris
- 68hc11 information and support for their line of boards

10.3) BBSs

The following BBSs have 8051 information:

Circuit Cellar, Inc.
- contains code from their magazine articles and from the
original Circuit Cellar articles in Byte magazine, also
contains many other interesting items
- The BBS is mentioned in the masthead of each issue (on the
table of contents page). Excerpts from the BBS appear in Ken
Davidson's ConnecTime column in every issue with a description
of how to access the system at the end of every column.
- (203)871-1988
- Voice: (203)875-2751
- Fax: (203)872-2204

Dunfield Development Systems
- support for their Micro-C C compiler and development tools
- includes a lot of nice goodies
- (613) 256-6289

ED Teck. Pubs BBS
- run by Fred Eady who writes for hobbyist magazines
- good source of information on the PIC
- (407)454-3198

Electronics Now
- contains code from their magazine articles
- (516)293-2283

Intel American Marketing Applications Support Bulletin Board System
- 16 lines, hi-speed modems (14.4K)
- Lots of useful info and files (including design examples)
- Full ANSI-BBS with color is recommended, but support for just
about all terminal types is provided
- 916-356-3600 (24 hours)
Auto config: 1200 thru 14.4K Baud
8 data bits, no parity, 1 stop

Iota Systems, Inc.
- Support for their line of hardware and software products
- (702)831-4732

Jens Holm's electronics BBS:
- one of a number of BBSs that are networked over most of the
industrial part of Europe
- +45-86-510356 (Denmark)
- distributes all shareware and freeware software which
relates to electronics
- system administrator - Jens Holm
jh...@bjarke.nrg.dtu.dk or Jens...@asgaard.dk

Don Lekei BBS
- support for the PIC line of microcontrollers
- (604)597-3479 (Canada)

Massilia Underground BBS (Marseille, France)
- +33-91794120
- fidonet 2:323/25
- not a commercial BBS
- microcontroller related stuff (assemblers, debuggers,
boards, etc), some 8051 stuff
- everything coming in is tested

Microchip BBS
- support for the PIC line of microcontrollers
- Contact by dialing the same number you would use to get to
Compuserve at 19200,n,8,1, except that you press +<CR> at the
(garbage) prompt, followed by MCHIPBBS as the host (instead of
CIS).

Micro Computer Control Corporation
- (609)466-4117

Motorola (Austin Texas) BBS
- terrific, has piles of stuff, only some of which is on
bode.ee.ualberta.ca
- (512) 891-3733 (Austin, Texas)
- V.32 9600 Baud modems w/ MNP-5
- 8 Data Bits, No Parity, 1 Stop Bit.

Other Motorola BBSs:
- Munich, Germany: 49-89-92103-111 (2400 baud)
- Stuttgart, Germany: 49-7031-275496 (19200 baud)
- San Diego, California: (619) 279-3907
- Toronto, Ontario, Canada: (416) 497-8989

National Semiconductor COP8 BBS
- (800)672-6427
- worldwide telnet to nscmicro.nsc.com

Protel (Microchip PIC software support)
- (408)243-0125

Parallax Inc.
- (916)624-7101

Philips Semiconductor (parent company of Signetics)
- support for: standard logic, programmable logic,
in-car electronics (planned), 8 and 16 bit microcontrollers,
I2C software, third party software, discrete semiconductors,
cross assemblers (general), RF (planned)
- PHIBBS is located in the Netherlands: +31-40-721102
- maximum 14400 baud / V42bis
- 24 hours a day available
- Help desk: +31-40-722749 (9.00 AM - 16.00 PM CET)

Philips Semiconductors (Signetics)
- support for their 8051 variants
- contains many good source code items
- partially mirrored on ftp.pppl.gov and nic.funet.fi
- (800)451-6644 or (408)991-2406

Texas Instruments microcontroller BBS
- (713)274-3700

10.4) Mailing Lists

68hc11
- for information, send empty message to list...@hipp.etsu.edu
- to join, send the message "subscribe mc68hc11 your_real_name"
to list...@hipp.etsu.edu

Basic Stamp
- to join, send the message "subscribe stamp-list" to
majo...@cybernetics.net

GCC compilers for embedded systems
- to join, send the message "subscribe crossgcc <your address>"
to majo...@first.gmd.de
- for those who are building a cross gcc compiler for an
embedded processor/system

Imagecraft C
- to join, send the message "subscribe icc11-list" to
list...@netcom.com

Minds-Online
- One mailing list is for announcing significant postings on the
Minds-Online ftp site.
- Another MODERATED mailing list will carry messages from real
engineers who are working on designs slated for volume
production. "No tire-kickers, no students, no academics, no
sleazy something-for-nothing ripoff artists, no hobbyists, and
no totally lost people will be able to post e-mail." (Uh, it
looks like that sort of leaves out yours truly, I certainly
belong in several, if not most, of those categories).
- to join, send the message "subscribe" to the email address:
minds-...@world.std.com

Mini Board and 6.270 board (68hc11)
- send a message containing the word "help" for directions to
list...@oberon.com
- mailing list address: robot...@oberon.com
- maintainer: gku...@oberon.com

Parallel Performance Group (PPG)
- series of monthly newletters on high-tech software topics
- for information send any e-mail to in...@ppgsoft.com

Philips Newsletter
- send Email with "subscribe" in the subject field to
Philip...@InetBSystems.us.com
- news, views, and articles (contributions welcome)
Philips Developers Forum
- send an Email message with the word "subscribe" in the subject
to Philips-fo...@InetBSystems.us.com
- technical discussions between engineers and developers

PIC
- to subscribe, send email to list...@mitvma.mit.edu
- send the message "SUB PICLIST" for standard subscription
- send the message "SUB PICDIGEST" to receive digested mailings
- list address is: P...@mitvma.mit.edu

__________________________________________________________

I disclaim everything. The contents of this article might be totally
inaccurate, inappropriate, misguided, or otherwise perverse - except for
my name (hopefully I got that right).

Copyright (c) 1997 by Russ Hersch, all rights reserved.
This FAQ may be posted to any USENET newsgroup, on-line service, or BBS
as long as it is posted in its entirety and includes this copyright
statement.
This FAQ may not be distributed for financial gain.
This FAQ may not be included in commercial collections or compilations
without express permission from the author.

-----------------------------------
Russ Hersch - ru...@shani.net