Drive a shutter makes microcontroller stuck

Other Hardware General Electronics
1

Hello here,

I try to drive a shutter (230VAC motor).

When no load is connected to the relays, everything works smoothly. But when I connect the load (my shutter), after a random number of relay switch (often just 1), the microcontroller freezes and never comes back to normal. I need to switch power off and on to make it start again.

I was initially thinking of Brown-Out Detection fuse being wrongly set, but after every failing switch, the uc would have reset by itself, nah? Then I found the following threads:

https://forum.arduino.cc/index.php?topic=420681.0
https://forum.arduino.cc/index.php?topic=438174.0
https://forum.arduino.cc/index.php?topic=117438.0

They all mention switching noise in relay driving AC load, that disrupts nearby electronics.
Mentioned solutions are:

  • a MOV installed between NO and COM contacts => would need some explanation
  • a snubber across the AC load => same
  • solid state relay (I try to drive a 230VAC load)
  • opto isolation (would require two separate power)

What solution should I choose in my situation?
Maybe I made something wrong designing my board or choosing my components, can you advice?

You'll find attached my schematic and board.

Thanks in advance for your help,
Nicolas

sch.png
sch.png3328×2218 57.5 KB

brd.png
brd.png458×556 11 KB

2

Yes common enough problem. Keep the wiring for the mains as far away as you can from the low voltage stuff. Add a snubber to the load to try and quench the spark.

Yes a SSR would help but make sure it is a zero crossing one otherwise the interference is worse than a relay.