ESP32 GPIO ADC Channel Error

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•

ukaton

I've been running into some issues since moving away from working in the Arduino IDE/PlatformIO to developing in Espruino for the ESP32.

The goal is to read 16 GPIO pins [GPIO's 0, 2, 4, 12, 13, 14, 15, 25, 26, 27, 32, 33, 34, 35, 36, 39] all of which can be read using the ESP32 libraries in either Arduino or PlatformIO but I receive the following ADC Channel Err if I try doing the same in Espruino IDE. I attached a js file of the code I used to test this out.

Please let me know if you have either had the same issue and/or have resolved this already. If you've resolved it, please let me know how you did it (I might be missing something critical here).

•

AkosLukacs in reply to @ukaton
I guess it's multiple things:
The page Robin linked says you can't use ADC2 when Wifi is active, and Wifi is active on Espruino & ESP32 by default.
Also, I don't think you should set the pins to output.

This code works for me (ok, just pulled the pins to 3v3 with a resistor, but results were around 0.999, when pulled to 3v3, so seems to be ok).
```
var pins = [D36,D37,D38,D39,D32,D33,D34,D35]
function readSensors(pins) {  
  pins.forEach(function(pin) {
    console.log(pin, ' -> ', analogRead(pin));
  });
}

readSensors(pins)
```
Prints something like this (D34 is pulled to 3v3, the rest is just floating):
```
D36  ->  0.576171875
D37  ->  0
D38  ->  0
D39  ->  0
D32  ->  0.10400390625
D33  ->  0.15966796875
D34  ->  0.99975585937
D35  ->  0.52758789062
```
Just multiply the results with 3.3 to get the voltage in volts, if you don't have any voltage divider.

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