Problem with Task and sprintf()

tcwden wrote on Thursday, February 08, 2007:

Hi,

After spending a bit of time on using Tasks, I’ve experienced a problem on using sprintf() in <stdio.h> provided by Microchip MPLAB C30.

Here are the symptoms:
1) When I used sprintf() in Task to print a string of characters, there are no problems.
2) When I used sprintf() in Task to print an integer or a floating point number, the function fails to work and seems to generate a reset on my chip.
3) When I used sprintf() in Coroutine, both characters and numbers work fine.

I wonder if anyone experienced the same problem at all? Is the problem caused by Task? or by sprintf()? or others?

Dennis

nobody wrote on Thursday, February 08, 2007:

Most likely a stack issue.  The biggest (and maybe only) disadvantage of GCC is that its standard library functions are pretty huge.  When you print just a string it probably replaces the call with a puts(), which is standard for GCC.  When you print numeric values it will start consuming an unpleasant amount of stack.  Try increasing the stack size of the task that uses printf.

Dave.

tcwden wrote on Thursday, February 08, 2007:

Thanks Dave,

That’s did the trick. I need to set the stack size to around 200 (i.e. 400bytes) to make things work.

Cheers.

Dennis