ESP32 Forum

We've ordered the ESP32-MINI-1 Module (not the development board, just the module), and I am very confused about which UART port is connected to which pins.

The datasheet shows:
U0RXD (GPIO3) on pin 35
U0TXD (GPIO1) on pin 36
U0CTS on pin 32
U0RTS on pin 33

U1RXD on pin 25
U1TXD on pin 26

The ESP32 AT User Guide says "All ESP32 modules use GPIO1 and GPIO3 as UART0"
It says also, "UART0 is used to download firmware and log output"

QUESTION #1: I understand that CTS and RTS are used with the AT commands, which is UART1, but then why are they called U0CTS and U0RTS ?

QUESTION #2: Do I use the flash_download_tool with pins 35/36 or pins 25/26 ?


To add to the confusion, the ESP32 AT User Guide says under section "Hardware Differences", that for MINI-1 Bin:
TX is pin 22
RX is pin 19
CTS is pin 15
RTS is pin 14

Question #3: Are these the pins for UART1 if I flash factory_MINI-1.bin onto the module?

And if so, Question #4: Why do they differ from the datasheet?

Rob

Hello Rob,
Actually, you could use any GPIOs with I/O function as the UART pins (TXD,RXD,CTS,RTS), because ESP32 chip has a GPIO matrix and IO_MUX.
You could see the chapter 4 <IO_MUX and GPIO Matrix> of ESP32 TRM: https://www.espressif.com/sites/default ... ual_en.pdf for more details.

ESP-AT doesn't use default UART pins (as you mentioned in ESP32-MINI-1 datasheet), but use the following configurations instead.

https://docs.espressif.com/projects/esp ... ico-series
(You could refer to ESP32-PICO Series which has same Hardware Connection Pinout to ESP32-MINI-1 module.)

Base on the above, let me try to clarify your confusions.
A1: The name is called according to its actual function, so that it has different names in the datasheet and ESP-AT.
A2: Use Pin 35 and Pin 36.
A3: Dead right. You can also change these pins if you would like to, according to https://docs.espressif.com/projects/esp ... -port-pins.
A4: Because the GPIOs of UART in the datasheet could be used to other functions (For the sake of firmware compatibility).

~

Thank you so much, that is a super response