[Icc-avr] stack size needed to use fp?

[Rich Webb]

> Good clue Rich! So my whole problem could be sort of an fp underflow.....
 > Wonder if I could hide an 0x55aa before and after the fp convert
 > buffer and check for buffer overrun after cprintfs? Any idea how to
 > find the address of the fp buffer?

I was thinking more along the lines of overflowing an sprintf(buf,...) 
buffer, rather than a side effect of printf() or cprintf(). I typically 
load a buffer with sprintf() and then fire the characters out the e.g., 
UART, one at a time when the UDRE (UART data ready empty) interrupt occurs.

In the fragment that I threw together I just pulled a nice round 
"#define BUFLEN 128" out of the air rather than trying to optimize space 
for the anticipated maximum length of the output string, or else I would 
have tromped over who knows what when the error strings were printed 
instead of the numerics.

I do use floats for user interfaces and such but the values are usually 
on the order of 1 to 100 (4.8 V, 23.7 C, ...) and had not hit upon the 
ftoa error message before this.