I don't know if any of you guys are still around and using this stuff -
I moved and am reviving a few of these 51/52 boards that I had built. Prior to moving I had decent luck with all these fixes though I don't quite remember where I was with any of this stuff seeing as it was 3 years ago.
I had a few motion sensors and some temp/humd based on these fixes and they were working great, no dips.
Not sure any of you will ever see this but hey it all worked.
Hi OSD, thanks for your input.
Those are the 4 relays on IO-MCU. I buzzed out the circuit and found that I had an open circuit on the 12v line to the relays.
Furthermore 2 of the relays indicator LEDs were illuminating, 2 were not.
I suspect, when I first juiced up the circuit on this MCU, the 2 relays fired, but I'd made the trace too thin for the required current. I wired up some jumper wire on the reverse of the PCB and the 2 relays started working.
The 2 that remain inoperable?
https://forum.arduino.cc/t/using-pins-a6-a7-on-pro-mini-compatible/118050
A6 and A7 can only be analogue inputs, cannot be digitally written to..... - so this part of my PCB is now redundant.
However, all in all, some good fault finding, found the two issues, and I'm now going away to re-think my PCB trace widths and reading the datasheets more accurately
Thanks