I have about 20 units in the field using the PIC16f870. Some have been in use for nearly 2 years without any problems but recently 2 units have come back as faulty. They have the same symptons, the program crashes during its interrupt routine, it doesn't return, it doeas execute the first few instructions though I can tell how far it gets before it crashes. After 15mS the watchdog resets and the cycle repeats. There appears to be no hardware faults anywhere. Ive read the data eeprom values and they are as expected, I can't read the code as its protected. Low voltage programming is disabled and code protection bits are set. The program does not have any routines for writing to code memory. If I reprogram the chip with the same software it now works faultlessly. Anyone got any ideas?
- posted
19 years ago