ESP32 Forum

Dear community,

I am new here and not sure if I am right here. I have 3 identical I2C slaves with the same address, want to avoid bit banging and an extra I2C multiplexing. I was wandering If I could connect my slaves to different pins and just switch the IO_MUX of teh ESP32S to the PINS of device I want to address. Checking the function "i2c_set_pin" within [1] looked like this could work. Of course I have to manage initialization of both connected devices seperately and switch only between communications. Do you think this could be a feasible way ?
Wouldn't this be a concept to avoid I2C multiplexers (at the cost of using more ESP32 pins for some applicatios by adding suich a generic feature? I checked teh runtime ending and re-starting a complete Wire interface whcih took about half a millisecond and would be too much.

Any feedback welcome with hints or reasons why such a concept will not work at all.

BR
BastelBaus

[1] https://github.com/espressif/esp-idf/bl ... /i2c/i2c.c

You probably could. Note that you may want to re-initialize the GPIOs you switched away from as normal GPIOs, otherwise the I2C signals may be sent to (but not read from) both pairs of pins.

That’s promising, thanks for the fast reply. I will give it a try!

I really works like charm ! Please find my short proof of concept: https://hackaday.io/page/21183-hacking- ... lexing-i2c. Thanks for your good advice, this was the reason why it did not work the first time .

Do you see any chances to create out of this a real feature within the ESP libraries ? I mean I sawe a lot of the code and handling of exception, so I don't believe my hack will work really reliable and in all cases. But maybe it could be made to a real feature ?

BR,
BastelBaus


P.S.: Somehowe the first post vanished, I tried to add a notification flag but maybe messed up with something ...

After adding WiFi to my code, I get quite soon after some accesses this error:
>> [ 44354][E][Wire.cpp:513] requestFrom(): i2cRead returned Error -1
I assume this has to to with the threading. Don't switching the pins does work perfekt. Any idea how to debug ?

BR
BastelBaus

Sorry, I have no experience with the Arduino I2C implementation. Could be that it's not re-entrant indeed, I don't know.