SeaTalk 1 RaspPi Wifi Interferance

[ozank]

I recently installed a MacArthur HAT with Raspi 4b (and power module), and I'm totally pleased with it. Thank you, everyone for this great piece of kit.

I got the SeaTalk1 working and able to read the data from the SignalK server; however, when I connect the Seatalk 12V (red) cable to 12V Switch, the wireless connection to the Raspberry pi becomes really unreliable (disconnects and fails to reconnect). I tried the following:

• Disconnected the SeaTalk data and SeaTalk 12 V connections, works like a charm
  
• Connected SeaTalk data, and powered the HAT with a normal 12V supply,  much better, but still disconnects and fails to reconnect from time to time
  
• Changed the wifi settings (Channel 1, 6, 11): no improvement
  
• Initially didn't connect the SeaTalk 1 GND to normal GND pin, but tried both ways didn't make a difference
  

I just wonder if other people had the same issue.

The problem seems to me as an EMI issue. I checked the MacArthur HAT schematic, it seems OK with the series resisters and 2-transistor schematic. It maybe a good idea to include extra filtering elements (L,C) to 12V SW, or convert it to an isolated input.
I'll try to use ferrite beads and R-C filters on the SW pin next.

My temporary solution at the moment is to use an external wifi router and connect to raspberry with the ethernet cable.

[Adrian]

Interesting observations.

Instinctively, for EMI I would have blamed the power module first, as that's the only component doing serious switching work. But it looks like that's fine in your setup.

Seatalk1 is rather slow and low current. And with the 10K resistors between GND and ST DATA and 12V SW, I also don't see much potential for ground loops.

Did you check for wiring that may obstruct the WiFi antenna of the Pi?

Are you powering the Pi from 5V via USB or 12V via MacArthur HAT?