My questions are regarding ADC channels. I simply do not fully understand some of the available informations.
- Total of 18 ADC channels?
There are listed on your page ESP32 Pinout Reference: Which GPIO pins should you use? – “The ESP32 peripherals include: 18 Analog-to-Digital Converter (ADC) channels” But I did not find the channels ADC1_CH1 and ADC_CH2 (GPIO 37 and GPIO 38) in ESP32. Also there is no reference of these channels in it’s hardware specification. The API Reference also describes ADC channels: “The ADC driver API supports ADC1 (8 channels, attached to GPIOs 32 – 39) ” but this information is rather confusing to me.
ESP32 does not seem to have implemented these two ADC1 channels. Or am I wrong?
- What about ACD2 module?
Does anyone know if there is really not possible to use any of the ADC2 channels? When using the BT / wifi module at the same time of course. I would like at least another one channel, e.g. ADC2_CH0 (GPIO 4).
It would be pretty crazy to have only 6 available instead of 18 declared ADC channels.
Those GPIOs (37 and 38) don’t exist on the WROOM series. They existe on this series of ESP32 chips (see page 8): https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf
As far as I know, the ADC2 pins don’t work well with Wi-Fi enabled.
One workaround is to switch off Wi-Fi, read the ADC2 channel and enable Wi-Fi again.