post_build.py

Import("env")
import os

def decode_flash_size_speed(byte_value):
    speed = byte_value[0] & 0x0f
    size = int((byte_value[0] & 0xf0) / 16)

    # As defined in esp_image_spi_freq_t
    spi_speed = {
      0: "40",
      1: "26",
      2: "20",
      0xf: "80"
    }
    speed_mhz = spi_speed.get(speed, "??")
    size_mb = str(1<<size)

    return "0x{} ({}MB, {}MHz)".format(byte_value.hex(), size_mb, speed_mhz)


def esp32_create_factory_bin(source, target, env):
    print("Generating factory bin for genuine esp units")

    #offset = 0x1000
    offset = 0x0
    flash_page_size = 256

    # The offset from begin of the file where the app0 partition starts
    # This is defined in the partition .csv file
    sketch_partition_start = 0x10000

    # Typical layout of the generated file:
    #    Offset | File
    # -  0x1000 | ~\.platformio\packages\framework-arduinoespressif32\tools\sdk\esp32\bin\bootloader_dout_40m.bin
    # -  0x8000 | ~\ESPEasy\.pio\build\<env name>\partitions.bin
    # -  0xe000 | ~\.platformio\packages\framework-arduinoespressif32\tools\partitions\boot_app0.bin
    # - 0x10000 | ~\ESPEasy\.pio\build\<env name>/<built binary>.bin
    
    new_file_name = env.subst("./${PROGNAME}-factory.bin")
    sections = env.subst(env.get('FLASH_EXTRA_IMAGES'))
    new_file = open(new_file_name,"wb")
    new_file.truncate() # Make sure no left over data is present from a previous build

    firmware_name = env.subst("$BUILD_DIR/${PROGNAME}.bin")

    # fill the file with 0xFF binary data to reflect 'erased and not yet written' data.
    # Make sure to use exactly the size that normally would be erased
    new_file.seek(0)

    total_size = sketch_partition_start + os.path.getsize(firmware_name)
    total_size = total_size - (total_size % flash_page_size) + flash_page_size

    new_file.write(bytes([0xff] * total_size))

    print("    {} | {}".format("Offset", "File"))
    for section in sections:
      sect_adr,sect_file = section.split(" ",1)
      print(" -  {} | {}".format(sect_adr,sect_file))
      source = open(sect_file,"rb")
      new_file.seek(int(sect_adr,0)-offset)
      new_file.write(source.read())
      if "bootloader" in sect_file:
        # Need to patch the bootloader to match the flash size
        flash_size = env.BoardConfig().get("upload.flash_size")

        # See esp_image_header_t for struct definition
        spi_speed_size_byte_offset = 3
        source.seek(spi_speed_size_byte_offset)
        spi_speed_size_byte = source.read(1)
        new_spi_speed_size_byte = spi_speed_size_byte[0] & 0x0f

        # As defined in esp_image_flash_size_t
        spi_size = {
          "1MB": 0x00,
          "2MB": 0x10,
          "4MB": 0x20,
          "8MB": 0x30,
          "16MB": 0x40
        }
        new_spi_speed_size_byte |= spi_size.get(flash_size, spi_speed_size_byte[0] & 0xf0)

        if new_spi_speed_size_byte != spi_speed_size_byte:
          new_byte = bytes([new_spi_speed_size_byte])
          print("           | Patch flash size in bootloader: {} -> {}".format(decode_flash_size_speed(spi_speed_size_byte), decode_flash_size_speed(new_byte)))
          new_file.seek(int(sect_adr,0)-offset + spi_speed_size_byte_offset)
          new_file.write(new_byte)

      source.close()

    
    firmware_start = sketch_partition_start-offset
    firmware = open(firmware_name,"rb")
    print(" - {} | {}".format(hex(firmware_start),firmware_name))
    new_file.seek(firmware_start)
    new_file.write(firmware.read())
    new_file.close()
    firmware.close()

env.AddPostAction("$BUILD_DIR/${PROGNAME}.bin", esp32_create_factory_bin)