Custom Partition Table

I. Experiment Objective

Learn the basic concepts and configuration methods of the ESP32 custom partition table. Through this experiment, you will understand the structure and function of the partition table and master how to customize the Flash partition layout for the MicroROS-V2 control board.

II. Experiment Principle

1. Keywords

2. Technical Architecture

The Flash space of the ESP32 is managed uniformly through the partition table. The partition table file (partitions.csv) is located in the project root directory and is converted to binary format during compilation and flashed to offset 0x8000 in Flash. At system startup, the Bootloader loads the corresponding application partition according to the partition table.

Partition table layout:

Flash address space:
0x8000  ┌───────────────┐
        │ Partition table │
0x9000  ├───────────────┤
        │ NVS partition    │
0xF000  ├───────────────┤
        │ PHY init params  │
0x10000 ├───────────────┤
        │ factory (app)    │
0x...   └───────────────┘

III. Experiment Steps

1. Hardware Preparation

2. Prerequisites

1. Set up the ESP32-IDF development environment

2. Connect the MicroROS-V2 control board to the computer via USB

3. Open the IDF configuration tool and specify partitions.csv as the partition table.

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   cd ~/esp/base_samples/partition_table
   idf.py menuconfig
   

   

   

3. Compile and Flash

​x

cd ~/esp/base_samples/partition_table
source ~/esp/esp-idf/export.sh
idf.py build flash monitor

4. Stopping Method

In the terminal, press Ctrl+] to exit the serial monitor.

IV. Experiment Result

After successful compilation and flashing, the Monitor window will output the following:

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hello yahboom
I (xxx) MAIN: Nice to meet you!

The normal startup of the control board indicates that the firmware has been correctly flashed and successfully booted through the custom partition table.

V. Program Analysis

Source code paths:

• Firmware source: ~/esp/base_samples/partition_table/main/main.c

• Partition table: ~/esp/base_samples/partition_table/partitions.csv

1. Partition Table Configuration File

Parameter definition file: ~/esp/base_samples/partition_table/partitions.csv

The partition table is defined in the partitions.csv file in the project root directory, with the following content:

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# Name,   Type, SubType, Offset,  Size,   Flags
nvs,      data, nvs,     0x9000,  0x6000,
phy_init, data, phy,     0xf000,  0x1000,
factory,  app,  factory, 0x10000, 3M,

This partition table defines three partitions:

The first two records of the partition table (nvs and phy_init) are system-required partitions. The factory partition after the third record is the application partition.

2. Main Program Logic

main/main.c is the sample main program. It only prints a welcome message to verify that the firmware has been correctly flashed to the custom partition:

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#include <stdio.h>
#include "esp_log.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"

static const char *TAG = "MAIN";

void app_main(void)
{
    printf("hello yahboom\n");
    ESP_LOGI(TAG, "Nice to meet you!");
}

3. The Role of the Partition Table

The partition table is the layout map of ESP32 Flash storage. It defines the name, type, offset address, and size of each partition. By default, ESP-IDF uses the factory default partition table. When the application needs a larger firmware space, OTA upgrade functionality, or custom data storage, the partition table must be modified.

Through a custom partition table, you can:

• Adjust the firmware size: enlarge the app partition to accommodate a larger firmware

• OTA upgrade: add two app partitions, ota_0 and ota_1, to implement wireless upgrades

• Custom storage partitions: add file system partitions such as fat and spiffs to store user data

• Optimize the layout: adjust the size allocation of each partition according to actual needs

4. SDK Configuration File Description

The sample directory also contains the sdkconfig.baiduyun.uploading.cfg file, which is a preconfigured SDK configuration file used for the Baidu Netdisk firmware flashing scenario. When you build with idf.py build, your own sdkconfig file is generated.

VI. Common Problems