using decimal bytes to control individual pins

[John in WI]

First off, a big thank you to this group... it has answers to many of my questions and I've learned a great deal. The jal libraries are fantastic.

I am trying to take a decimal formatted byte (sent serial from a PC) and convert that to turning on/off individual pins.

My 8 pins are on different ports.... 4 on portb 4 portc. Other pins on C and B ports are being used for other, non output purposes. 

Often, when I program in basic or c++ there are functions to format a decimal byte to a string of 0's and 1's..... then, using string functions like MID I pick out each bit and get it's value that way.

I am not finding any way to format a decimal byte to a binary or ways to pick out individual characters of a string with JAL. 

I suspect there might be a simple way to do this?

Thanks again.

[Rob Hamerling]

Hi John,.

On 29-08-12 15:47, John in WI wrote:
> First off, a big thank you to this group... it has answers to many of my
> questions and I've learned a great deal. The jal libraries are fantastic.

Thanks!

> I am trying to take a decimal formatted byte (sent serial from a PC) and
> convert that to turning on/off individual pins.
> My 8 pins are on different ports.... 4 on portb 4 portc. Other pins on C
> and B ports are being used for other, non output purposes.
>
> Often, when I program in basic or c++ there are functions to format a
> decimal byte to a string of 0's and 1's..... then, using string
> functions like MID I pick out each bit and get it's value that way.

That is a very inefficient way to do things (in a PIC)! You better learn
how to handle individual bits in a byte! And it is not so difficult once
you understand it. Example:

var byte x = "A"

In ASCII notation the bit-pattern of "A" is 0b0100_0001 and that of "a"
is 0b0110_0001. So if you need to know if x contains a capital A or a
lowercase a then you could do something like:

if (x & 0b0010_0000) then -- check if bit 5 is 1
-- { whatever }
end if

And if you want to be sure that x contains a lowercase letter regardless
if it already uppercase or not then you could do

x = x | 0b0010_0000 -- set bit 5 to 1

Note: bits in a byte are numbered right to left from 0 to 7.

Hope you understand this, once you do: there are more interesting
bit-operations to learn!

> I am not finding any way to format a decimal byte to a binary or ways to
> pick out individual characters of a string with JAL.

The libraries 'Format' and 'Print' have conversion procedures.

Regards, Rob.

--
R. Hamerling, Netherlands --- http://www.robh.nl

[Joep Suijs]

Hi guys,

I was just composing a reply, when Rob his message came in, which
contains most of what I was about to say. Just want to add that JAL
has a way to name individual (or multiple) bits within a byte, which
could be usefull in this case.

This:
var byte reg ; your input value
var bit reg_0 at reg:0
var bit reg_1 at reg:1
Defines a single byte, and creates names for the lower two bits of
this bytes - so this are the same bits (see 'at' in the definition).
Next:
reg = 1
puts 0b00000001 in reg, so reg_0 becomes one (true) and reg1 becomes
zero (false).
You can use these values to define pins like:
pin_b0 = reg_0
pin_b3 = reg_1


Hope this helps (and does not contain too much typos - I have not
compiled the code before posting).

Joep


2012/8/29 Rob Hamerling <robham...@gmail.com>:

> --
> You received this message because you are subscribed to the Google Groups
> "jallib" group.
> To post to this group, send email to jal...@googlegroups.com.
> To unsubscribe from this group, send email to
> jallib+un...@googlegroups.com.
> For more options, visit this group at
> http://groups.google.com/group/jallib?hl=en.
>

[John in WI]

You guys are great! 

I think I know the direction to head now. Once I figure it out I will post here what I came up with.

Thanks