Conflict Between Wifi & analogRead()?

[kher-MN]

Is anyone seeing a conflict with analogRead() values when #include <WiFi.h> is included in a sketch? analogRead works great without WiFi.h included; however, if WiFi.h is included then the analogRead values returned are all maxed out (4096 values). Note I've tested on pins 12, 14, 26 & 27.

[palomarcoder]

I found a note here that may be relevant: https://www.espressif.com/sites/default/files/documentation/esp32_hardware_design_guidelines_en.pdf

Pin1, Pin43 and Pin46 are the analog power supply pins. Pin3 and Pin4 are the power supply pins for the power amplifiers. It should be noted that the sudden increase in current draw, when ESP32 is in transmission mode, may cause a power rail collapse. Therefore, it is highly recommended to add another 0603 10 uF capacitor to the power trace, which can work in conjunction with the 0402 0.1 uF capacitor.

[JeroenVanOort]

I've been having trouble with this as well. After a lot of trial and error I have found out that analogRead will work on some pins while using WiFi, 32 and 36 are examples of those pins. I hope this helps when trying to find out why this happens.

[nissimzur]

Hi
It seems the ESP32 pin 32 is been used as SDO to flash. Are you sure you can use is as analogRead input?
Please call my Skype nissim.test

[igrr]

This happens because ADC2 pins can not be used when WiFi is used.

On the other hand, ADC1 pins can be used even when WiFi is enabled.

[hkotkanen]

@JeroenVanOort thank you kindly, switched to a pin you indicated and got mine working.

@igrr many thanks for the information! Your statement is so casual and matter-of-fact, but this thread seems to be then only place that documents this ...feature. Was I supposed to have found it out from another source?

[CarlosGS]

A few months ago I got around this issue by periodically soft-restarting the ESP32 to measure from ADC2; then turning on wifi to send the data.

Unfortunately this has been broken in latter updates, right now if you issue esp.restart() after turning on wifi, the ADC2 no longer works. Now it is needed to physically disconnect power.

Any thoughts on why esp.restart() doesn't restore all radio registers to their default state?

[me-no-dev]

There is a fix coming for ADC2 and WiFi soon :)

[pieman64]

@me-no-dev any news on the ADC2 fix?

[JulienHai]

any news? when will adc2 be fixed?

[palomarcoder]

Any estimated time? I was really hoping to use this in a project over the holiday.