How to Set AT Port Pins¶

This document introduces how to modify AT port pins in the firmware for ESP32, ESP32-S2, ESP32-C3, and ESP8266 series of products. By default, ESP-AT uses two UART interfaces as AT ports: one is to output logs (named as log port below) and the other to send AT commands and receive responses (named as command port below).

To modify the AT port pins of your ESP device, you should:

clone the esp-at project;
modify the pins either in the menuconfig utility or the factory_param_data.csv table;
compile the project to generate the new bin in build/customized_partitions/factory_param.bin;
flash the new bin to your device.

This document focuses on modifying the pins. Click the links above for details of other steps. Below is the document structure:

ESP32 Series
ESP32-S2 Series
ESP32-C3 Series
ESP8266 Series

Note

To use other interfaces as the AT command port, please refer to AT through SDIO , AT through SPI , or AT through socket for more details.

ESP32 Series¶

The log port and command port pins of ESP32 AT firmware can be user-defined to other pins. Refer to ESP32 Technical Reference Manual for the pins you can use.

Modify Log Port Pins¶

By default, the ESP32 AT firmware provided by Espressif uses the following UART0 pins to output log:

TX: GPIO1
RX: GPIO3

When compiling your esp-at project, you can modify them to other pins with the menuconfig utitlity:

./build.py menuconfig –> Component config –> Common ESP-related –> UART for console output
./build.py menuconfig –> Component config –> Common ESP-related –> UART TX on GPIO#
./build.py menuconfig –> Component config –> Common ESP-related –> UART RX on GPIO#

Modify Command Port Pins¶

By default, UART1 is used to send AT commands and receive AT responses, and its pins are defined in Column uart_port, uart_tx_pin, uart_rx_pin, uart_cts_pin, and uart_rts_pin of the factory_param_data.csv .

You can change them directly in your factory_param_data.csv table:

Open your local factory_param_data.csv file.
Locate the row of your module.
Set uart_port as needed.
Set uart_tx_pin and uart_rx_pin as needed.
Set uart_cts_pin and uart_rts_pin to be -1 if you do not use the hardware flow control function.
Save the table.

ESP32-S2 Series¶

The log port and command port pins of ESP32-S2 AT firmware can be user-defined to other pins. Refer to ESP32-S2 Technical Reference Manual for the pins you can use.

Modify Log Port Pins¶

By default, the ESP32-S2 AT firmware provided by Espressif uses the following UART0 pins to output log:

TX: GPIO43
RX: GPIO44

When compiling your esp-at project, you can modify them to other pins with the menuconfig utitlity:

./build.py menuconfig –> Component config –> Common ESP-related –> UART for console output
./build.py menuconfig –> Component config –> Common ESP-related –> UART TX on GPIO#
./build.py menuconfig –> Component config –> Common ESP-related –> UART RX on GPIO#

Modify Command Port Pins¶

By default, UART1 is used to send AT commands and receive AT responses, and its pins are defined in Column uart_port, uart_tx_pin, uart_rx_pin, uart_cts_pin, and uart_rts_pin of the factory_param_data.csv .

You can change them directly in your factory_param_data.csv table:

Open your local factory_param_data.csv file.
Locate the row of your module.
Set uart_port as needed.
Set uart_tx_pin and uart_rx_pin as needed.
Set uart_cts_pin and uart_rts_pin to be -1 if you do not use the hardware flow control function.
Save the table.

ESP32-C3 Series¶

The log port and command port pins of ESP32-C3 AT firmware can be user-defined to other pins. ESP32-C3 Technical Reference Manual for the pins you can use.

Modify Log Port Pins¶

By default, the ESP32-C3 AT firmware provided by Espressif uses the following UART0 pins to output log:

TX: GPIO21
RX: GPIO20

When compiling your esp-at project, you can modify them to other pins with the menuconfig utitlity:

./build.py menuconfig –> Component config –> Common ESP-related –> UART for console output
./build.py menuconfig –> Component config –> Common ESP-related –> UART TX on GPIO#
./build.py menuconfig –> Component config –> Common ESP-related –> UART RX on GPIO#

Modify Command Port Pins¶

By default, UART1 is used to send AT commands and receive AT responses, and its pins are defined in Column uart_port, uart_tx_pin, uart_rx_pin, uart_cts_pin, and uart_rts_pin of the factory_param_data.csv .

You can change them directly in your factory_param_data.csv table:

Open your local factory_param_data.csv file.
Locate the row of your module.
Set uart_port as needed.
Set uart_tx_pin and uart_rx_pin as needed.
Set uart_cts_pin and uart_rts_pin to be -1 if you do not use the hardware flow control function.
Save the table.

ESP8266 Series¶

The log port and command port pins of the ESP8266 AT firmware can be user-defined to other pins, but with limited options. Please refer to ESP8266 Technical Reference Manual for more details.

Modify Log Port Pins¶

By default, the ESP8266 AT firmware provided by Espressif uses UART1 to log output. UART1 only supports GPIO2 as the TX pin, and the pin should not be modified.

However, you could modify the log port from UART1 to UART0 by:

./build.py menuconfig –> Component config –> Common ESP-related –> UART for console output

Modify Command Port Pins¶

By default, ESP8266 AT firmware uses UART0 to send AT commands and receive AT responses. The UART0 pins are defined in Column uart_port, uart_tx_pin, uart_rx_pin, uart_cts_pin, and uart_rts_pin of the factory_param_data.csv .

The UART pins can be changed, but there are only two choices: GPIO15 as TX pin, GPIO13 as RX or GPIO1 as TX, GPIO3 as RX. Below are the detailed steps:

Open your local factory_param_data.csv file.
Locate the row of your module.
Set uart_port as needed.
Set uart_tx_pin and uart_rx_pin to GPIO15 and GPIO13, or GPIO1 and GPIO3.
Set uart_cts_pin and uart_rts_pin to be -1 if you do not use the hardware flow control function.
Save the table.

For example, if you need to set GPIO1 (TX) and GPIO3 (RX) to be both the log port and command port of ESP-WROOM-02, do as follows:

Set log port to UART0: ./build.py menuconfig –> Component config –> ESP8266-specific –> UART for console output –> Default: UART0
Open your local factory_param_data.csv.
Find the row of WROOM-02, set uart_tx_pin to 1, uart_rx_pin to 3, uart_cts_pin to -1, uart_rts_pin to -1, and then save the table.

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