ESP32 TX and RX pins

ESPHome
1

Hi. I would like to use the Adafruit ESP32 V2 feather to gather data for home assistant via the TX and RX pin. The pin numbers are 7 and 8 (see Adafruit Learning System). However, the compilation of the firmware fails with the error “This pin cannot be used on ESP32s and is already used by the flash interface (function: Flash Data 1)”. There are no other TX and RX pins on this board. How can I use the TX and RX pin on this board?

The configuration:

esp32:
board: adafruit_feather_esp32_v2
framework:
type: arduino

uart:

  • id: uart_modbus
    baud_rate: 9600
    tx_pin: 8 # GPIO8 gives same result
    rx_pin: 7 # GPIO7 gives same result
2

GPIO6 to GPIO11 are used for the ESP32 flash memory. ESP32 can assign the UART RX/TX to most GPIO pins. I’d recommend just using any convenient pair between GPIO16 and GPIO33.

3

@mulcmu The pinout diagram of the board dazzles a little bit. Is it important to use pins with a uart indication (like 19 and 22) or can it be something random (like 27 and 33)?

4

Adafruit seem to be telling us their boards are wired differently.

5

Can I just use different pins and name them RX and TX in the configuration despite they have a different label on the board itself?

6

Most of the pins have multiple use possibilities. Look at the pinout of your board… it will tell you which pins can do what and they’re usually color coded too.