Variables in ram being overwritten

[eric]

Ram variables being overwritten in my 18F2525 code (or 18F2520)

in the .lst file the Compiler make this assignment
.................... MY_IP_BYTE4=210;
1710: MOVLW D2
1712: MOVWF xFB <- MY_IP_BYTE4 assigned to ram location xFB

Looking though the .lst file there is only 2 more uses of this register. Both are just reading the location.

Yet after about an hour, or several hours, the value this location has changed to x54 (from xD2)! This over written value has been consistently changed to x54.

This also can happen to other variables but the "adjusted" values are not as consistent. I am assuming that I have only one problem but it may be more than one effect. Focusing on the this one since the altered value is repeatable.

All interrupts are off (I think)
#fuses H4,NOWDT,PROTECT,NOWRT,NOLVP

CCS PCH C Compiler, Version 3.249, 31890
ROM used: 31182 bytes (65%)
Largest free fragment is 15568
RAM used: 590 (15%) at main() level
699 (18%) worst case
Stack: 16 location

I am using my code, which has been solid for a year, combined with the some CCS example code for driving the ENC28J60. The example code, or my code when run alone did not seem to have this problem.

ANY suggestions on what might be happening here?

Eric

[Ttelmah]

Are you using pointers anywhere?.
What array accesses are you using?.
What is listed in the sym file, immediately in front of the corrupted value(s)?. Is this accessed by either a pointer, or as an array?.
The commonest cause of this, is failure to 'bounds check' an index value for an array, or used with a pointer (the compiler does not do this, and the chip has no hardware protection for this), so the wrong value gets accessed.

Best Wishes

[eric]

Thanks for the reply- I will check out your suggestions today.

Eric