All IO reset

[Kongfu1]

Hi,

Using 18F452 PIC for PID control with many other h/w staffs build in same box for more than 2 years.

Not all the time, all IO pins of PIC will be reset as well as disabling interrupt for unknown reason. When this happens, SW still be alive because io of h/w watch dog is still toggling in safety task. In same task, some logical is used to monitor the bit of interrupt enable (0xff2-bit7). If it is 0, reboot cpu. But, it is not always working.

This problem may happen once for 3 months or even longer time.

Please advice.
Howard

[FvM]

Do you also observe other kinds of failure, e.g. unintended CPU resets, or only events of the said kind? Did you check the Microchip silicon errata sheets for known issues?

If the problem isn't caused by an electrical phenomenon (as supply overvoltage) it's mostly a case of unintenional programmed action, due to a processor or software bug. It may be meaningful, to shield any code, that may be responsible for the observed behaviour against irregular execution, at least for trial.

[Kongfu1]

Yes. I checked errata sheets, there are two modules with known issues maybe root causes for this.

Thanks for the helps.