Core 2 unit with M5Go2, Serial Port C and external Elechouse RFID V 1.2

  • On a Core 2 unit with M5Go2 bottom, I need to connect an external RFID board (Elechouse) but its not working yet, just getting a "None" or b'x\00' data return.

    The connection is UART based using Port C (Blue), Pins TXD2 14, RXD2 13 : Supports UART with 115200 data rate configured to UART2). In order to test the Core2 side I did loop configuration sending RX to TX with a jumper wire and I worte a string "Testing_Serial" by an UART write command. This worked fine. When connecting the external board I get back a string with b'x\00'. The wires to the external device are crossed TX->RX, RX<-TX and the two power wires. Not sure, if there is a command sequence required to activate the data transmission and RFID data readout at the device. The board is reading tags and is blinking. Any insight are welcome.

  • Hello @falbriard

    do you have a link to the specifications of the Elechouse RFID v1.2? The ones I found from Elechouse (which support UART) state in the specification that UART TTL interface is 5 V. While Port C power is 5 V the data lines TX and RX are only 3.3 V. Maybe that is the issue?


  • @felmue You are right, it seems to be a voltage mismatch. The UART requests 5V, but ESP32 delivers only 3.3V.
    Reading: "On-board level shifter, Standard 5V TTL for I2C and UART, 3.3V TTL SPI"
    Find more:
    Time to buy a M5stack reader unit and use the standard UiFlow drivers. Thanks!