I am using a combination of Microchip PIC18F4520 and PIC16F73 in a controller which interfaces multiple heating systems for different applications. One huge issue I am running into is fossil fuel furnace / boiler spark igniter noise causing micros to reset. Does anyone have experience / tips on how to remedy this? We have isolation relays on the controller to isolate the furnace voltage from the controller voltage.
To this point, we've added another layer of external isolation relays to remedy this, but as you can guess, this is not acceptable for the end customer.
At this point I am thinking a low-pass filter may be a route to look at, but it seems this may end in the same result (system cycling).
Any tips would be appreciated.