minimalist FPGA system
John Williams
I am pondering the requirements for a minimalist FPGA-based device:
Power supply
Clock generator
FPGA
JTAG header for configuration via Xilinx parellel cable or similar
Have I missed anything?
Secondly, for the device to do its own FPGA configuration, I would
expect to add
flash (or serial prom)
small CPLD for configuration control
Any comments and useful references?
Thanks,
John
Nicholas C. Weaver
John Williams <j2.wi...@qut.edu.au> wrote:
>Hi folks,
>
>I am pondering the requirements for a minimalist FPGA-based device:
>
>Power supply
Depending on the FPGA and the IO, you may need 2 or even 3 voltages.
I remember seeing some cute little switching power supplies which did
this.
>Clock generator
Probably want it socketed, but not necessarily. If soldered on, make
it high frequency, its easier to downclock then upclock.
>FPGA
>JTAG header for configuration via Xilinx parellel cable or similar
>
>Have I missed anything?
Bypass capacitors. Probably a blinkenlight and a reset button, and
probably a power button too. You might also want to toss on a small
LCD display, they are cheap and only need a few pins, but can convey a
lot of information that way.
Also, an FPGA which can't talk to anything is pretty useless. I'd say
include a high density connector to a daughtercard which you can put
whatever sorts of IOs you want.
>Secondly, for the device to do its own FPGA configuration, I would
>expect to add
>
>flash (or serial prom)
>small CPLD for configuration control
Xilinx makes an ASIC to do this (SystemACE), you can hook it up to a
compact flash part. IF you use flash, use compact flash, having
removability and program-anywhere is nice.
--
Nicholas C. Weaver nwe...@cs.berkeley.edu
Peter Alfke
John Williams wrote:
> Secondly, for the device to do its own FPGA configuration, I would
> expect to add
>
> flash (or serial prom)
> small CPLD for configuration control
>
>
You do not need any CPLD. The FPGA is "smart enough" to pull its
configuration out of a serial PROM. ( using CCLK )
Peter Alfke, Xilinx Applications
Tony Burch
What you have just described is essentially
the BurchED board...
http://www.burched.com.au/B5Spartan2.html
Our philosophy has always been to provide
users with the "minimalist" flexible system, which
gives access to ALL of the user I/Os, and
allows it to be used as a base platform for
prototyping a new system, or building into
equipment (one-offs, or OEM).
The B5-Spartan2e+ has
* Spartan2E 300K gate XC2S300E device
* JTAG and serial mode configuration download pod cable
* Header programmable PLL oscillator (1 - 100MHz)
* All the cables and hardware you need for a basic FPGA system
Oh, yes, and you also get one test pushbutton
switch (which I almost always use for the
system Rst), and one test LED.
The B5-Spartan2e+ board is US$179.
We also supply plug-on modules, for easily
expanding system resources. In eight days time,
we are releasing a flash prom configuration module,
which plugs onto the B5-Spartan2e+.
Hope that is of interest,
Best regards
Tony Burch
http://www.BurchED.com
Low cost FPGA boards, for System-On-Chip
prototyping and education
"John Williams" <j2.wi...@qut.edu.au> wrote in message
news:3D7BED91...@qut.edu.au...
nospam
Given an FPGA with serial PROM connected to the configuration pins do the
Xilinx tools and download cables support in circuit programming of the PROM
through the FPGA JTAG port?
Jerry D. Harthcock
The Musketeer (all-for-one) FPGA stamp, is actually both a minimalist
and maximalist FPGA development platform, especially for
FPGA-embeddable microcontrollers. For about $175 you get everything.
JTAG real-time debugger, JTAG boundary scan controller, device
programmer. No need for serial FLASH because the Musketeer's on board
FPGA is an Actel ProASIC+, re-programmable FPGA with ASIC-like
features.
There is a product brief and news release you can download at:
www.quickcores.com. There are also some ready-made microcontroller
designs (STAPL format) that you can download.
Regards
Jerry
John Williams
"Nicholas C. Weaver" wrote:
>
> Depending on the FPGA and the IO, you may need 2 or even 3 voltages.
> I remember seeing some cute little switching power supplies which did
> this.
Any useful links? I'm targetting very low power consumption (who
isn't?!), so the provision of several voltages is potentially
problematic. Certainly don't want the heating/resistive losses
associated with voltage regulators, so maybe miniature switched mode
might be the way to go.
> >Clock generator
>
> Probably want it socketed, but not necessarily. If soldered on, make
> it high frequency, its easier to downclock then upclock.
I haven't played with Xilinx clock management yet, DCM and all that.
But if I have a fixed external clock, say 133MHz, can I expect to
achieve reasonable application sdpecific clock frequencies within the
device? ie 133MHz coming in, down-clock that to 100, or 66, or 50, or
whatever? Obviously integer clock division is trivial, but what about
non-integer?
Also, can I get the FPGA to down-clock, and also export that reduced
clock to external circuitry?
> >Have I missed anything?
>
> Bypass capacitors. Probably a blinkenlight and a reset button, and
> probably a power button too.
Yep, good call, especially for prototyping. "Is it working? Yes, I've
got a 2 HZ blinking light, just like I expected!"
> You might also want to toss on a small
> LCD display, they are cheap and only need a few pins, but can convey a
> lot of information that way.
Hmm interesting idea, once again could be very useful for prototyping.
> Also, an FPGA which can't talk to anything is pretty useless. I'd say
> include a high density connector to a daughtercard which you can put
> whatever sorts of IOs you want.
Yup.
> Xilinx makes an ASIC to do this (SystemACE), you can hook it up to a
> compact flash part. IF you use flash, use compact flash, having
> removability and program-anywhere is nice.
I read the system ACE doco - very interesting stuff.
Thanks for your reply.
John
Nicholas C. Weaver
John Williams <j2.wi...@qut.edu.au> wrote:
>> Depending on the FPGA and the IO, you may need 2 or even 3 voltages.
>> I remember seeing some cute little switching power supplies which did
>> this.
>
>Any useful links? I'm targetting very low power consumption (who
>isn't?!), so the provision of several voltages is potentially
>problematic. Certainly don't want the heating/resistive losses
>associated with voltage regulators, so maybe miniature switched mode
>might be the way to go.
I remember seeing ones from Lucent a couple years ago, but can't find
a reference.
Some companies make small ones that BGA mount for cellphone
applications (4-6V input, 1.5V output or similar), but the current was
only 1/2 an amp (so under a watt, you probably want to be ABLE to draw
a few watts), that google was able to find.
http://www.vishay.com/document/10106/10106.pdf
has ones that are 1.5W max power, 85-90% efficient, 3.6 to 6V input,
1.5 to 3.6V output (settable by a resister).
I don't know if these in particular can be run in parallel, but the
lucent ones could.
>I haven't played with Xilinx clock management yet, DCM and all that.
>But if I have a fixed external clock, say 133MHz, can I expect to
>achieve reasonable application sdpecific clock frequencies within the
>device? ie 133MHz coming in, down-clock that to 100, or 66, or 50, or
>whatever? Obviously integer clock division is trivial, but what about
>non-integer?
Integer power of two is easy. Integer any power is easy if you don't
mind a 50/50 duty cycle. You could feed it back through the DLL to
give you back a 50/50 duty cycle IIRC.
>Also, can I get the FPGA to down-clock, and also export that reduced
>clock to external circuitry?
No problem. And you can PLL it so it is the same phase as the
internal one, at least on the virtex families, IIRC.
>> Bypass capacitors. Probably a blinkenlight and a reset button, and
>> probably a power button too.
>
>Yep, good call, especially for prototyping. "Is it working? Yes, I've
>got a 2 HZ blinking light, just like I expected!"
You probably want a hard reset, a "soft" reset (a signal pin), and 2
blinkenlights. You can just use surface mount LEDs and switches.
>> You might also want to toss on a small
>> LCD display, they are cheap and only need a few pins, but can convey a
>> lot of information that way.
>
>Hmm interesting idea, once again could be very useful for prototyping.
Probably overall, they ARE cheap. And it is amazing teh amount of
information you can convey for debugging purposes.
Jan Gray
> >> LCD display, they are cheap and only need a few pins, but can convey a
> >> lot of information that way.
> Probably overall, they ARE cheap. And it is amazing teh amount of
> information you can convey for debugging purposes.
For prototyping, I have an on-chip text display generator core that uses a
handful of LUTs and two 512 B BRAMs to drive a VGA monitor at (5+1)*32
pixels by (8+2)*3*16 lines, ~60 Hz. The second BRAM is used as a 96x5x8
character generator ROM for display of ASCII characters 0x20-0x7F.
Externally, IIRC, it requires 3 pins, a couple of resistors, and a VGA
connector. (I'll grant you that if all you've got on hand is a 21" monitor,
it looks a little funny.)
Jan Gray, Gray Research LLC
John Williams
Jan Gray wrote:
>
> > >> You might also want to toss on a small
> > >> LCD display, they are cheap and only need a few pins, but can convey a
> > >> lot of information that way.
>
> > Probably overall, they ARE cheap. And it is amazing teh amount of
> > information you can convey for debugging purposes.
>
> For prototyping, I have an on-chip text display generator core that uses a
> handful of LUTs and two 512 B BRAMs to drive a VGA monitor at (5+1)*32
> pixels by (8+2)*3*16 lines, ~60 Hz.
Anyone for Pong?! :)
> (I'll grant you that if all you've got on hand is a 21" monitor,
> it looks a little funny.)
A bit like plugging an Atari 2600 into a video projector!
Still, it's an interesting and cheap solution to get info out of the
FPGA during prototyping. A couple of resistors and a VGA socket are
much cheaper than the serial-driven LCD displays I've seen around the
place.
John
Hal Murray
> got a 2 HZ blinking light, just like I expected!"
I'd go slightly farther and suggest several debugging connections -
places where you can conveniently connect a scope and/or an external
input.
Might as well put LEDs on them unless you are really tight
on board space. But I like LEDs.
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