How to Set AT Port Pin

In the project esp-at, UART0 and UART1 are used by default. And users can change those UART pins according to their actual hardware design. Since the esp-at supports both ESP32 and ESP8266, there are some differences between the configurations.

ESP32 AT

The UART pin of ESP32 can be user-defined to other pins, refer to ESP32 Technical Reference Manual. In the official Espressif ESP32 AT bin, UART0 is the default port to print log, using the following pins:

TX ---> GPIO1
RX ---> GPIO3

The log pins can be set in make menuconfig > Component config > Common ESP-related > UART for console output. UART1 is for sending AT commands and receiving response, but its pins can be changed. The pins of UART1 is in the factory_param.bin, they can be changed in the component file customized_partitions/raw_data/factory_param/factory_param_data.csv. The UART1 pins may be different for different ESP modules. More details of factory_param_data.csv are in the How_to_create_factory_parameter_bin.md.

For example, the configuration of the ESP32-WROOM-32 is as the following table.

Parameter Value
platform PLATFORM_ESP32
module_name WROOM-32
magic_flag 0xfcfc
version 2
module_id 1
tx_max_power 78
uart_port 1
start_channel 1
channel_num 13
country_code CN
uart_baudrate 115200
uart_tx_pin 17
uart_rx_pin 16
uart_cts_pin 15
uart_rts_pin 14
tx_control_pin -1
rx_control_pin -1

In this case, the pins of ESP32-WROOM-32 AT port is:

TX ---> GPIO17
RX ---> GPIO16
CTS ---> GPIO15
RTS ---> GPIO14

For example, if you need to set GPIO1 (TX) and GPIO3 (RX) to be both the log pin and AT port pin, then you can set it as the following steps.

  1. Open component file customized_partitions/raw_data/factory_param/factory_param_data.csv.

  2. Choose the line of WROOM-32, set uart_port to be 0, uart_tx_pin to be 1 and uart_rx_pin to be 3, and then save it.

    Parameter Value
    platform PLATFORM_ESP32
    module_name WROOM-32
    magic_flag 0xfcfc
    version 2
    module_id 1
    tx_max_power 78
    uart_port 0
    start_channel 1
    channel_num 13
    country_code CN
    uart_baudrate 115200
    uart_tx_pin 1
    uart_rx_pin 3
    uart_cts_pin -1
    uart_rts_pin -1
    tx_control_pin -1
    rx_control_pin -1

  3. Recompile the esp-at project, download the new factory_param.bin and AT bin into flash.

ESP8266 AT

ESP8266 has two UART ports, UART0 and UART1. UART1 only supports TX pin to print debug log. UART0 has both TX and RX pin, to send AT commands and receive response. Unlike ESP32, UART0 pins of ESP8266 cannot be set to any pins, there are only two choice, GPIO15 as TX pin, GPIO13 as RX or GPIO1 as TX、GPIO3 as RX.

The default setting of ESP8266 AT UART is：

  • Use UART0 is the AT port to send/receive AT commands/responses. GPIO15 is the UART0 TX, GPIO13 is the UART0 RX.
  • Use UART1 to print debug log, GPIO2 is the UART1 TX pin.

For example, if you need to set GPIO1 (TX) and GPIO3 (RX) of ESP-WROOM-02 to be both the log pin and AT port pin, then you can set it as the following steps.

  1. make menuconfig > Component config > ESP8266-specific > UART for console output > Default: UART0

  2. Open component file customized_partitions/raw_data/factory_param/factory_param_data.csv, choose the line of WROOM-02, set uart_tx_pin to be 1 and uart_rx_pin to be 3, and then save it.

    Parameter Value
    platform PLATFORM_ESP8266
    module_name WROOM-02
    magic_flag 0xfcfc
    … …
    uart_baudrate 115200
    uart_tx_pin 1
    uart_rx_pin 3
    uart_cts_pin -1
    uart_rts_pin -1
    … …

  3. Recompile the esp-at project, download the new factory_param.bin and AT bin into flash.

ESP32S2 AT

The UART pin of ESP32S2 can be user-defined to other pins, refer to ESP32S2 Technical Reference Manual. In the official Espressif ESP32S2 AT bin, UART0 is the default port to print log, using the following pins:

TX ---> GPIO43
RX ---> GPIO44

The log pins can be set in make menuconfig > Component config > Common ESP-related > UART for console output. UART1 is for sending AT commands and receiving response, but its pins can be changed. The pins of UART1 are configured in the factory_param.bin, they can be changed in the component file customized_partitions/raw_data/factory_param/factory_param_data.csv. The UART1 pins may be different for different ESP modules. More details of factory_param_data.csv are in the How_to_create_factory_parameter_bin.md.

For example, the configuration of the ESP32S2-WROVER is as the following table.

Parameter Value
platform PLATFORM_ESP32S2
module_name WROVER
magic_flag 0xfcfc
version 2
module_id 0
tx_max_power 78
uart_port 1
start_channel 1
channel_num 13
country_code CN
uart_baudrate 115200
uart_tx_pin 17
uart_rx_pin 21
uart_cts_pin 20
uart_rts_pin 19
tx_control_pin -1
rx_control_pin -1

In this case, the pins of ESP32S2-WROVER AT port is:

TX ---> GPIO17
RX ---> GPIO21
CTS ---> GPIO20
RTS ---> GPIO19

For example, if you need to set GPIO43 (TX) and GPIO44 (RX) to be both the log pin and AT port pin, then you can set it as the following steps.

  1. Open component file customized_partitions/raw_data/factory_param/factory_param_data.csv.

  2. Choose the line of WROVER, set uart_port to be 0, uart_tx_pin to be 43 and uart_rx_pin to be 44, and then save it.

    Parameter Value
    platform PLATFORM_ESP32S2
    module_name WROVER
    magic_flag 0xfcfc
    version 2
    module_id 0
    tx_max_power 78
    uart_port 0
    start_channel 1
    channel_num 13
    country_code CN
    uart_baudrate 115200
    uart_tx_pin 43
    uart_rx_pin 44
    uart_cts_pin -1
    uart_rts_pin -1
    tx_control_pin -1
    rx_control_pin -1

  3. Recompile the esp-at project, download the new factory_param.bin and AT bin into flash.

  4. If you don’t want to compile the entire project in the third step, you can refer to How_to_create_factory_parameter_bin.md.