shadowbrush:
Bingo, with that code change I'm getting temperature readings with grounded probes. This is great, and I can't thank you enough to point me into the right direction! I was about to throw the towel with the cumuli towering up and my motorglider still on the ground without engine temps.Yes, I've been fighting ground noise when using Auber Instruments pyrometers to indicate engine temps in the past, and learned a bit about ground loops. I hope this won't be a major issue again this time. I'm fine averaging readings in 10 second intervals, still fast enough to warn about engine overheating.
What exactly did you change in the code? I have three thermocouples connected to three Adafruit breakout boards. One is connected to a motor housing. The other to are in thermowells measuring water temp. I have had lots of problems (mostly reading 32F) maybe this grounding issue is the cause.