How to Generate Factory Parameter Bin


This document explains how to generate a customized ESP-AT factory parameter bin file (factory_MODULE_NAME.bin) for your module. For example, you may want to self-define the country code, RF restriction, or UART pins in your ESP-AT firmware. The two tables below allow you to define such parameters.

The following describes how to generate a customized factory parameter bin by modifying the two tables.


The factory_param_type.csv table lists all the parameters that you can define as well as the offset, type, and size of each parameter. It is located in customized_partitions/raw_data/factory_param/factory_param_type.csv.

The table below provides some information about each parameter.

param_name Note
description Additional information of the module, which is prompted when you are building the ESP-AT project.
magic_flag The value must be 0xfcfc.
version The version of factory parameter management for internal use. The current version is 3. It is not recommended to modify it.
reserved1 Reserved.
tx_max_power Wi-Fi maximum tx power for ESP32 and ESP32-C3: [40,84]. See ESP32 and ESP32-C3 tx power setting range for details.
uart_port The UART port that is used to send AT commands and receive AT responses.
start_channel Wi-Fi start channel.
channel_num The total channel number of Wi-Fi.
country_code Country code.
uart_baudrate UART baudrate.
uart_tx_pin UART tx pin.
uart_rx_pin UART rx pin.
uart_cts_pin UART cts pin; it should be set to -1 if not used.
uart_rts_pin UART rts pin; it should be set to -1 if not used.
tx_control_pin For some boards, the tx pin needs to be separated from MCU when power on; it should be set to -1 if not used.
rx_control_pin For some boards, the rx pin needs to be separated from MCU when power on; it should be set to -1 if not used.
reserved2 Reserved.
platform The platform (or called chip series) that the current firmware runs on.
module_name The module that the current firmware runs on.


This factory_param_data.csv table holds the values for all the parameters defined in factory_param_type.csv. It covers the modules of ESP32 and ESP32-C3 series. You can customize your factory parameter bin by modifying the values in the table. It is located in customized_partitions/raw_data/factory_param/factory_param_data.csv.

Add a Customized Module

This section demonstrates how to add a customized module in factory_param_data.csv and generate the factory parameter bin for it with an example. Assuming that you want to generate the factory parameter bin for an ESP32 module named as MY_MODULE, its country code is JP, Wi-Fi channel is from 1 to 14, and other parameters stay the same with WROOM-32 module of PLATFORM_ESP32, you can do as follows:

Modify factory_param_data.csv

Set all parameter values for MY_MODULE in the factory_param_data.csv table.

Firstly, insert a row at the bottom of the table, and then enter the following parameter values:

  • param_name: value
  • platform: PLATFORM_ESP32
  • module_name: MY_MODULE
  • description: MY_DESCRIPTION
  • magic_flag: 0xfcfc
  • version: 3
  • reserved1: 0
  • tx_max_power: 78
  • uart_port: 1
  • start_channel: 1
  • channel_num: 14
  • country_code: JP
  • 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

The modified factory_param_data.csv file is as follows.


Modify esp_at_module_info Structure

Add customized module information in the esp_at_module_info structure in at/src/at_default_config.c.

The esp_at_module_info structure provides OTA upgrade verification token:

typedef struct {
    char* module_name;
    char* ota_token;
    char* ota_ssl_token;
} esp_at_module_info_t;

If you do not want to use OTA features, member 2 ota_token and member 3 ota_ssl_token should be set to NULL. Member 1 module_name must correspond to the field module_name in the factory_param_data.csv file.

The modified esp_at_module_info structure is as follows:

static const esp_at_module_info_t esp_at_module_info[] = {
#if defined(CONFIG_IDF_TARGET_ESP32)
    {"WROOM-32",        CONFIG_ESP_AT_OTA_TOKEN_WROOM32,       CONFIG_ESP_AT_OTA_SSL_TOKEN_WROOM32 },        // default:ESP32-WROOM-32
    {"ESP32-D2WD",      NULL,  NULL },   // ESP32-D2WD

#if defined(CONFIG_IDF_TARGET_ESP32C3)

Macro CONFIG_ESP_AT_OTA_TOKEN_MY_MODULE and macro CONFIG_ESP_AT_OTA_SSL_TOKEN_MY_MODULE are defined in the header file at/private_include/at_ota_token.h.

#if defined(CONFIG_IDF_TARGET_ESP32)


Recompile the Project and Select the Customized Module

After adding the customized module information, recompile the whole project according to Compile ESP-AT Project and select the customized module when configuring the project:

Platform name:

Module name:
1. WROOM-32
2. WROVER-32
3. PICO-D4
4. SOLO-1
5. MINI-1 (description: ESP32-U4WDH chip inside)
6. ESP32-D2WD (description: 2MB flash, No OTA)
7. ESP32_QCLOUD (description: QCLOUD TX:17 RX:16)
8. MY_MODULE (description: MY_DESCRIPTION)

You can find the factory parameter bin generated in esp-at/build/customized_partitions folder after the build is completed.

Add a Customized Parameter

This section demonstrates how to add a customized parameter with an example. Assuming that you want to add the parameter date for MY_MODULE and set it to 20210603, you should do as follows:

Modify factory_param_type.csv

Define the parameter date in the factory_param_type.csv.

Firstly, insert a row at the end of the table, and then set the name, offset, type, and size of the parameter:

param_name offset type size
description -1 String 0
date 88 String 9

Modify factory_param_data.csv

In the factory_param_data.csv, insert a column named as date to the right of the last column, then set its value to 20210603 for MY_MODULE.

The modified CSV table is as follows:


Process a Customized Parameter

You can customize processing functions to process the customized parameter date. This section is just a simple output:

static void esp_at_factory_parameter_date_init(void)
    const esp_partition_t * partition = esp_at_custom_partition_find(0x40, 0xff, "factory_param");
    char* data = NULL;
    char* str_date = NULL;

    if (!partition) {
        printf("factory_parameter partition missed\r\n");

    data = (char*)malloc(ESP_AT_FACTORY_PARAMETER_SIZE); // Notes
    assert(data != NULL);
    if(esp_partition_read(partition, 0, data, ESP_AT_FACTORY_PARAMETER_SIZE) != ESP_OK){

    if ((data[0] != 0xFC) || (data[1] != 0xFC)) { // check magic flag, should be 0xfc 0xfc

    // sample code
    // users can customize the operation of processing date
    // here is just a simple print out of the date parameter
    str_date = &data[88];   // date field offset address
    printf("date is %s\r\n", str_date);



Recompile the Project

Recompile the whole project according to Compile ESP-AT Project.

You can find the factory parameter bin generated in esp-at/build/customized_partitions folder after the build is completed.

Modify Factory Parameter Data on an Existing Module

Assuming that you need to modify the factory parameter data of an existing module in factory_param_data.csv, you choose one of the following options:

Recompile the Whole Project

Open the factory_param_data.csv and modify the parameters as needed.

Recompile the ESP-AT project according to Compile ESP-AT Project to generate the factory parameter bin in esp-at/build/customized_partitions folder.

Only Recompile the Factory Parameter Bin

Firstly, clone the entire ESP-AT project.

Secondly, navigate to the root directory of ESP-AT project, enter the following command, and replace some parameters:

python tools/ --platform PLATFORM --module MODULE --define_file DEFINE_FILE --module_file MODULE_FILE --bin_name BIN_NAME --log_file LOG_FILE
  • Replace PLATFORM with the platform of your module. It must correspond to the platform in the factory_param_data.csv.
  • Replace MODULE with your module name. It must correspond to the module_name in the factory_param_data.csv.
  • Replace DEFINE_FILE with the relative path of factory_param_type.csv.
  • Replace MODULE_FILE with the relative path of factory_param_data.csv.
  • Replace BIN_NAME with factory parameter bin file name.
  • Replace LOG_FILE with the file name stored the module name.

Below is the example command for MY_MODULE:

python tools/ --platform PLATFORM_ESP32 --module MY_MODULE --define_file components/customized_partitions/raw_data/factory_param/factory_param_type.csv --module_file components/customized_partitions/raw_data/factory_param/factory_param_data.csv --bin_name ./factory_param.bin --log_file ./factory_parameter.log

After the above command is executed, the three files will be generated in the current directory:

  • factory_param.bin
  • factory_parameter.log
  • factory_param_MY_MODULE.bin

Download the new factory_param_MY_MODULE.bin into flash. ESP-AT provides to do it. Execute the following command under the root directory of ESP-AT project and replace some parameters:

python esp-idf/components/esptool_py/esptool/ -p PORT -b BAUD --before default_reset --after hard_reset --chip auto  write_flash --flash_mode dio --flash_size detect --flash_freq 40m ADDRESS FILEDIRECTORY
  • Replace PORT with the port name

  • Replace BAUD with baud rate

  • Replace ADDRESS with the start address in flash. ESP-AT has strict requirements on the ADDRESS parameter. The address of factory parameter bin varies from firmware to firmware. Please refer to the table below:

    factory parameter bin download addresses
    Platform Firmware Address
    PLATFORM_ESP32 All firmware 0x30000
    PLATFORM_ESP32C3 MINI-1 Bin 0x31000
    PLATFORM_ESP32C3 QCLOUD Bin 0x30000
  • Replace FILEDIRECTORY with the relative path of the factory parameter bin.

Below is the example command to flash the generated factory parameter bin to MY_MODULE:

python esp-idf/components/esptool_py/esptool/ -p /dev/ttyUSB0 -b 921600 --before default_reset --after hard_reset --chip auto  write_flash --flash_mode dio --flash_size detect --flash_freq 40m 0x30000 ./factory_param_MY_MODULE.bin

Directly Modify Factory Parameter Bin

Open the factory parameter bin with a binary tool, and directly modify the parameters in the corresponding position according to the parameters offset in factory_param_type.csv.

Download the new factory_param.bin into flash (see Downloading Guide).