Here is a little report on my progression. In short : it still doesn't work!
I checked that the pin "works" correctly by connecting a relay to test in OUTPUT mode, and a push button (to test in INPUT) : it works!
I checked, double checked and triple checked the setup (wires, connections,...), everything is good.
I ran the same code on a Wemos D1 Mini (ESP8266) : it works.
At this point, I'm lost? The pin and the code seem good, but it can't detect the sensor.
One thing I notice is that this weird whistling sound coming out of the board (not sure if it comes from the speaker or not) when the OneWire lib bitbangs the OneWire protocol on the pin.
So, I made another test program that toggles the pin rapidely (at the speed of the onewire lib - ~50µs) : I hear the sound!
I'll try to find an oscilloscope to check the signal on the pin, as I suspect that "something" is going wrong when the pin is driven at "high" speed.
In the meantime, I hope that someone with more electronical knowledge will help me find a solution!
@daslolo Glad its working again.... I'm using standard Home edition on this machine - but the LTSB windows version you are using sounds like a good option I might use on another system. Thanks for mentioning....
And today deep sleep eats up 0.10A, either this meter is ~ or m5stack power consumption is whimsical. And after a few minutes deepsleep consumes 0.08A... I think what's happening here is the USB is charging the battery, as the battery is fuller the regulator drops current usage.
So I took out the battery module and tada - current usage is stable.
One core doing not much = 0.06A
One core heavy gfx = 0.08A
Two cores = 0.08A
Two cores with heavy gfx = 0.10A
deep sleep = 0.01A, that's 1000x the esp32 specs but similar to boards which don't even have a display.
@m5stack, holding the button for programming works fine. Resetting is the issue with my unit. In some cases, even with the bottom plate off, the unit will not reset and run the downloaded firmware unless I let it sit a while. Other times it works fine.