I'm using Numato 16 GPIO board to switch relays on 8 Channel Relay Module. Until no 220V load is connected to the relay all works fine and I can switch on/off relay using Serial port command to GPIO as many times as I want. But once I connect actual device (in my case pump) through the relay – relay switches on (or off) the device and GPIO board stops communicating through COM port. After reconnecting GPIO USB cable it works again one time. Is my micro bieng stung by arcs radiating? Do I need some sort of snubber?
Here is image of the current wiring:
Previously I had GPIO Board feeding from USB, but was experiencing exactly same problem. Thought maybe it's not getting enough power from USB so rewired to use external 5V supply as it is now.
I wonder maybe somebody had similar problem or has an idea what can be done to solve it?
Best Answer
It seems that it's an EMC problem rising from the surge current of your load (a motor pump). If you supply the relay board with the same 5v as the Numato board, it's possible to have some return spike on the 5v that hangs the Numato CPU when the pump start. Try to put some ceramic capacitors (one 10uF and one 100nF) next to the 5V connector of the relay board.