@exie @felmue I have never worked with micropython, however ESP32 can act as a slave on the I2C bus without any issues, irrespective of the pins that are used (any pair of GPIO can, in fact, be used as front-end for the I2C interface). I've taken a peek to the linked thread and the idea of continuously polling the bus to reply to an address as a slave is quite cumbersome and to say the least, inefficient.

hey @sheepDog, take a look at the following repo: M5Stack-IDF-4.0, maybe it can be of use to setup a IDF 4.0 environment as you'd like

Hey everyone, I published a GitHub repo here which can be used to build project using ESP-IDF 4.0 (possibly up) and the M5Stack Arduino core.
It doesn't differ that much from the original sources, but has some minor bugfixes and it changes the CMakeLists file in the M5Stack component so to make it work correctly.

Let me know if there are issues using it, although I'm fairly new to git and very new to esp32 and m5stack so I can't guarantee I'll be able to solve them.

Cheers

Thanks! That's perfect, cause I need at least 3 of them for an usable application, and 5 would be ideal. I wonder, would it make sense (to your knowledge) to decouple G2 and G12 from the electrodes at boot time, by placing a MOSFET inbetween the connections, which in turn would be activated at runtime from another GPIO of the M-Bus, acting as output? In this way it wouldn't be necessary to physically disconnect the electrodes every time.

Thanks for the reply. However, could they be used as this kind of input afterwards? Like, plugging the electrodes in after the booting has completed?
Also, is 0 definitely unavailable for this purpose?

Hi everyone, I'm about to get my first M5Stack, and for the main use I have for it I'd need capacitive inputs, or at least 3 of the 10 available on the esp32.
In the image below (from the esp32 datasheet), you can see there are 10 GPIOs capable of getting capacitive input, named from TOUCH0 to TOUCH9.

Looking at the schematics, it seems that a good part of this inputs are already dedicated to some other function, namely

• GPIO32
• GPIO33
• GPIO27
• GPIO14
  for the LCD display
• GPIO4
  for the SD card.

The remaining GPIOs available are 0,2,12,13,15; and they are all marked as "IO" as alternative function in the M-Bus definition of the schematic (see below)

Of these, only GPIO0 seems to be dedicated to some hardwired function (Auto-Download), while also having a pullup resistor, while the rest of them don't seem to be bound to anything.

Can anybody confirm if the only available pins for touch input are 2,12,13,15 (and possibly 0) ? Or, are they also unavailable for some other reason?

Thanks everyone for your time!