I have a 14m on a professional pcb which uses three inputs for temperature via DS18B20. 3 outputs operate LCDs and two run MOSFETS to switch pump loads of < 1 amp each. Diodes to prevent possible Backfeed from the pumps are in place after the FETs.
I have made many of these circuits without problems but I have one user who is finding that the PIC program is corrupting every few weeks. A cold restart does not help, the program no longer runs or runs incorrectly and the only cure is to reprogram the chip.
The SERIN is tied down correctly with 22k and 10k and the power supply is through a 7805 regulator.
I'm running out of ideas and can only think to add a chunky capacitor (100uF?) to the power in and tie the two unused inputs low with 10k resistors. Can anyone suggest what might be causing the program to corrupt in this way and any possible remedies?
I have made many of these circuits without problems but I have one user who is finding that the PIC program is corrupting every few weeks. A cold restart does not help, the program no longer runs or runs incorrectly and the only cure is to reprogram the chip.
The SERIN is tied down correctly with 22k and 10k and the power supply is through a 7805 regulator.
I'm running out of ideas and can only think to add a chunky capacitor (100uF?) to the power in and tie the two unused inputs low with 10k resistors. Can anyone suggest what might be causing the program to corrupt in this way and any possible remedies?