I was programming an esp32 and got some strange results. I tried to read adc2_channel_8 and the voltage jumped from 0v to around 1v. when I re-power the micro and don't read the adc the pin stays put at 0v like it should.
My suspicion is that the adc somehow is shorted to the 1.1v reference. just want a second opinion from someone more seasoned.
Does a pin you are reading connected to ground? Why you expecting 0? If it's floating you can read random numbers.
It's pulled to ground with a 4K7 resistor.
I can now confirm that this was a short. I measured the potential of my soldering iron and got 2.5v ac. The soldering iron was grounded but the ground connection did not contact with the tip properly due to oxidation between the connecting layers.
Do not buy a shitty soldering iron.
As a note about the ESP32.
If ESP32 is connected to a computer and something happens to the ESP32 to cause the 5V line to go higher than 5V, the design of the ESP32 allows that over voltage to get into the computer. Weird stuff starts happening to the computer. I use a powered USB hub to connect the ESP32 to the computer, that way the hub takes the hit and not the computer.
ESP32's blow quicker than fuses. I use a crowbar, to a fuse, across the 5V power regulator input for one ESP. I use a 5.1 Zener to trigger the crowbar. Saves buying ESP's.