ESP32-Flocker is a shell script used to concatenate several esp32 binaries and their application launcher into a single firmware.

The goal is to ease the creation of all-in-one-firmware application suites without having to manually edit the partitions.csv file or requiring the creation of a custom bootloader.

In this scenario, the factory partition which holds the applications launcher is near the end of the flash space, just before spiffs, OTA0 is available for flashing, and all space in between is used to stack the applications.

Example of generated partition scheme with 16MB flash size:

  # 9 Apps + Factory
  # Name,   Type,  SubType,  Offset,   Size,     Flags, Comment
  nvs,      data,  nvs,        0x9000,   0x5000,,
  otadata,  data,  ota,        0xe000,   0x2000,,
  ota_0,    0,     ota_0,     0x10000, 0x200000,,       OTA0 (available slot)
  ota_1,    0,     ota_1,    0x210000, 0x090000,,       WiFiManager
  ota_2,    0,     ota_2,    0x2a0000, 0x1f0000,,       BLEScanner
  ota_3,    0,     ota_3,    0x490000, 0x0c0000,,       I2CScanner
  ota_4,    0,     ota_4,    0x550000, 0x090000,,       SerialBridge
  ota_5,    0,     ota_5,    0x5e0000, 0x0c0000,,       HomeAssistant
  ota_6,    0,     ota_6,    0x6a0000, 0x090000,,       Camera
  ota_7,    0,     ota_7,    0x730000, 0x090000,,       Tetris
  ota_8,    0,     ota_8,    0x7c0000, 0x110000,,       Pacman
  ota_9,    0,     ota_9,    0x8d0000, 0x420000,,       Leftover space (available slot)
  firmware, app,   factory,  0xcf0000, 0x100000,,       Factory Launcher
  spiffs,   data,  spiffs,   0xdf0000, 0x200000,,
  coredump, data,  coredump, 0xff0000, 0x010000,,.

The shell script will:

• Read a JSON settings file
• Gather/build the binaries for every applications, including the launcher
• Create a custom partition scheme
• Generate the NVS data for the launcher
• Merge all binaries
• Flash the ESP

⚠️ All included applications must meet the application requirements.

ℹ️ applications[] items listed in the JSON settings file and can be either of:

• Path/git-url to .bin file
• Path/git-url to arduino project source
• Path/git-url to platformio project source

ℹ️ Project sources will be compiled with arduino-cli and platformio according to their nature.

ℹ️ Although the recommended application launcher with this shell script is M5Stack-SD-Updater's M5Stack-FW-Menu example, any custom launcher will work as long as it's capable of enumerating the ota partitions and setting any of them as bootable.

The bash script needs a JSON settings file to work, here's an example:

{
  "name": "MyApplicationSuite",
  "fqbn": "esp32:esp32:m5stack-cores3:DebugLevel=debug",
  "build_properties": "-DMY_CUSTOM_FLAG",
  "factory":
  {
    "name": "M5Stack-FW-Menu",
    "path": "~/Arduino/libraries/M5Stack-SD-Updater/examples/M5Stack-FW-Menu",
    "depends": [ "M5Stack-SD-Updater", "ESP32-Chimera-Core" ]
  },
  "applications":
  [
    {
      "name":"WiFiManager",
      "path": "/path/to/Arduino_Projects/WiFiManager/examples/SmartConfig"
    },
    {
      "name":"BLEScanner",
      "path": "https://github.com/tobozo/ESP32-BLECollector.git",
      "depends": [ "SQLiteEsp32", "ESP32-Chimera-Core", "NimBLE-Arduino" ]
    },
    {
      "name":"SerialBridge",
      "path": "/path/to/Arduino_Projects/SerialBridge",
      "depends": [ "SoftwareSerial" ]
    },
    {
      "name":"HomeAssistant",
      "path": "/path/to/Platformio_Projects/SmartHass#env-name"
    },
    {
      "name":"Camera",
      "path": "/path/to/Precompiled_Projects/Camera.bin"
    }
  ]
}

• build_properties: additional compilation flags e.g. -DMY_CUSTOM_FLAG for arduino-cli
• flash_size: defaults to 16MB
• flash_freq: defaults to 80m
• flash_mode: defaults to dio
• target_port: defaults to /dev/ttyUSB0
• baud_rate: defaults to 921600
• flashfs_type: data partition type, defaults to littlefs
• flashfs_size: data partition size, defaults to 2MB
• factory_partsize: factory partition size, defaults to 1MB
• applications[].depends: list of arduino-cli library dependencies for a given app, assumed as all satisfied if empty or missing
• verify: grep sketches and launcher source to verify that M5StackUpdater library is used, defaults to true

Uncommenting the directories entry in arduino-cli.yml file only makes sense if no local installation of Arduino IDE exists e.g. a CI is running the bash script and needs to cache downloads on a different volume to save bandwidth

In any other situation it is safe to keep the directories block commented out.

Every /data/ folders from the listed applications will be merged into a single filesystem image, and only one of spiffs/littlefs/fatfs can be used (default is littlefs), obviously every application using the flash filesystem will have to agree on this.

Every application must provide a way to load the factory partition, this can be achieved by using M5Stack-SD-Updater library:

• With M5Stack-SD-Updater and through the lobby by calling checkFWUpdater() instead of the usual checkSDUpdater()
• With M5Stack-SD-Updater outside the lobby by calling Flash::loadFactory()
• Without M5Stack-SD-Updater by implementing this function:

#include "esp_ota_ops.h"
#include "bootloader_common.h"

void loadFactory()
{
  auto factory = esp_partition_find( ESP_PARTITION_TYPE_APP,  ESP_PARTITION_SUBTYPE_APP_FACTORY, NULL );
  if( !factory ) {
    log_e( "this partitions scheme has no factory partition");
    return;
  }

  auto factory_partition = esp_partition_get(factory);

  if( !factory_partition ) {
    log_e( "Failed to find factory partition" );
    return;
  }
  // Set partition for boot
  auto err = esp_ota_set_boot_partition ( factory_partition );
  // restart on success
  if ( err != ESP_OK ) {
    log_e( "Failed to set boot partition" ) ;
  } else {
    log_i("Will reboot to factory partition");
    esp_restart() ;
  }
}

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