[Icc-avr] Spontanious RAM problems

[Jason Geiger]

Greetings,

I am having a problem with an ATMEGA128 which I am a little unsure how
to debug and I was hoping to get some basic ideas as to where to start.
Any and all suggestions are welcome and appreciated!

I have a few timing/counting variables that are spontaneously changing
from their value of 0 to something that is non-zero.  I have a
TimeKeeper (ISR) routine counting those variables back down to zero.  In
Main() I act on them, usually when their value is equal to 1 - then I
set them to zero until I need to get to them.   I believe this is pretty
standard fare for keeping track of timing.

What could be causing these variables to spontaneously change from zero?
Perhaps I am abusing ICC somehow.  
Some notes and considerations.
 - I do boundary checking with any arrays - especially noting that some
of these are RX and TX data packets.
 - I use a LOT of structures.  Some people seem to think this is great
for organization. Others argue that it's awful for code efficiency.
- My Software and Hardware stack seem to be much bigger than I need,
based on some quick calculations and verified by that handy stack
checker that I got from one of you on here.  (Sylvain?)
 - Related; I do not have nested interrupts.
- 5 volt circuit - Brown out fuse is enabled and set at 4 volts.  Could
this be hardware? Power supply issues?

How do I know these are happening spontaneously?  Most of the timer
variables that I am noticing this problem are set exclusively by from
incoming data packets and they are being set when I have the circuit
detached from anything else.  They are also variables that are more
recently.  I could be happening to others, but I have not noticed that
yet.

Void Main()
{
	If (Time2.DoSomething == 1)
{
	DoSomething();  // like set and LED pin high
		PORTB = 0x01; //Uh oh, this LED is on now, nothing else
can cause that!
	Time2.DoSomething = 0;
}
}

Void TimeKeeperISR()
{
if (Time2.DoSomething > 1)	Time2.DoSomething--;
}



Thoughts? Ideas?  Thank you ahead of time,

Jason Geiger


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