AVR-Chat

On Wed, Feb 08, 2006 at 10:49:08PM -0600, Chuck Hackett wrote:
> I guess I'd agree with Tom that assembler forces you to KNOW your
> hardware environment better which is a good thing.  But, just because
> one is using a higher level language like C doesn't relieve you from
> having to know quite a lot about the hardware - assuming you're
> interacting with the world outside the chip which is the point in
> microcontrollers.

When I'm asked this question I recommend the AVR, avr-gcc, and the
original K&R C book. Then add a reminder the K&R book "teaches" C by
implementing common library utilities. That printf(), getchar(),
putchar(), malloc(), etc, are not C, but nothing more than functions no
different than any other one may write.

For embedded applications stay as far away as possible from the canned
library functions. Especially printf() and malloc().

Also spend a lot of time looking at the generated assembly output. Is
not so important as to be able to write assembly as it is to be able to
read and understand what the compiler thought of your instructions. This
way you know how expensive it is to attempt to abstract the UART via
indirection in a structure. You know that 16 bit values require two
accesses which an interrupt may jump in between. All those little things
that differentiate code which happens to work vs. solid code which
always works and is easy to maintain.

One parting note, use some sort of version system. CVS, Subversion,
something, anything, from the start. Get used to frequently updating
your repository with concise comments as to what you were doing or what
motivated the changes. Comments in the code are important but the
quality of comments in your commits are just as important.

-- 
David Kelly N4HHE, dkelly@HiWAAY.net
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Whom computers would destroy, they must first drive mad.