Stamp C3 /C3U pinout diagrams

  • Hi,

    The documentation ( & does not show any pins assigned to I2C or SPI. Is it correct that the pins have not been linked to the ESP chip, not enabling the functions?

  • @slyderule Hi!
    C3 has the I2C "PORT A" on the left side beside the USB-C port, pins G1 and G0. You can see it on the supplied sticker!
    "Module peripheral interface resources ADC, GPIO, SPI, UART, I2C, I2S, PWM, RMT, DMA, USB serial port, TWAI"(from the Specifications list)
    Hope this helps, cheers, Terry

  • @teastain ... thank you, this helps a little. I need to know which pin is clock and which is data. For my use case I will be using the Stamp much in the way one would use any other ESP32 board, wiring it to sensors directly and not using the M5 ports.

    the M5Stack team usually does an awesome job with their documentation (on the links I posted in the OP).

  • @slyderule Esp32 is an oddball in that it doesn’t have hard set pins instead it can have multiple functions assigns to pins based on the job it’s being used on.

  • @slyderule The C3 appears to be SCL G0 and SDA G1...but...I cannot get the Stamp-C3 to read an ENVII temp sensor on I2C. There is no Arduino IDE M5Stack example to go on, only the much more complicated IDF environment.
    Still working on it, but I may make my own community post to see if M5Stack or @felmue can help!

  • Hello @teastain

    i think you can use the M5Atom ENVII example as basis.

    • Replace #include <M5Atom.h> with #include <Arduino.h>.
    • Replace M5.begin() with Serial.begin(115200);.
    • Remove all lines with M5.dis.
    • Replace Wire.begin(26, 32); with Wire.begin(1, 0);.
    • Connect ENVII unit to M5StampC3 port A.

    Note: I do not have the ENVII unit, so I cannot test this myself.


  • @felmue said in Stamp C3 /C3U pinout diagrams:
    Hi Felix. I took your suggestions and on the Stamp-PICO it works, but not the C3.
    The I2C port pins 1, 0 show DC connectivity ref ground, but no scope activity on the pins while it is running.
    It would be nice if M5Stack provided a simple Arduino IDE example of a I2C device on C3!!! I am going to try a different I2C M5Stack sensor (TOF) Which I am familiar with. (I did a RoverC with avoidance sketch!)

  • @felmue OK! I tied the very complicated TOF sensor because it is in-line code, no damned Library and...
    ...It works on C3.
    The expected activity on the G1, G0 was as it should be.
    So, thanks for your help, I will use this event as a plateau and work to trouble shoot the ENV myself, probably with in-line code, No Lib !!!
    Vielen Dank!