Reply To: Issue with USB not connecting

Nuts that it sounds like the switch might be oxidizing. The switch solves a power vampire problem by switching off the CP210x – so I would expect the processor to carry on working.  You might check what the humidity levels are in the unit, ensure that its largely isolated from fogs and possibly put in some dessicant to dry it out. At one point I mad some electronics (not the Mayfly) in a temperate forest  – and some fungus or something grew across the reset line causing the processor to permanently reset.

For purely monitoring the processor, I use the FTDI link to do that. This means it can be monitored in the field for its current state, and doesn’t reset when connecting to the USB .

Diagrams here, showing only the Tx line connection https://github.com/neilh10/ModularSensors/wiki/Test-Equipment-FTDI-cable

For a full connector with Rx and Tx it can also download programs to the processor.