OTA and Factory partition

[MRIIOT]

How come all the OTA partition examples omit the factory partition?

If I wanted to rollback to factory for some reason, I would want to do something like this:

fp = Partition.find(label='factory')
fp.set_boot()
machine.reset()

[glenn20]

The default 4MB flash size on the original ESP32 devices only provided enough space for 2 firmware partitions that could fit a typical micropython application image (~1.5MB), so there is not enough room for a fallback factory partition in addition to the (minimum 2) OTA partitions.

If you have more flash storage, you can add a factory partition as well if you want (eg. see https://github.com/glenn20/mp-image-tool-esp32), though its not clear how this provides any advantage over 2 (or 3) OTA partitions.

[glenn20]

The default micropython bin files include the bootloader, the partition table and the application image. When you perform an ota update, you only want to write a new application image into the OTA partition and not overwrite the bootloader and partition table. I am guessing otatool.py automatically extracts the application image from the firmware file. Note that the .app-bin files on https://micropython.org/download/ESP32_GENERIC/ are application image files that can be used for OTA updates.

My https://github.com/glenn20/mp-image-tool-esp32 tool can also extract these application image files from a regular micropython firmware file.

[glenn20]

Whoops... I just realised you may have been referring to the application image when you mentioned micropython.bin. If that is the case, I have no idea why you need to use esptool.py. I don't use it and my ota updates work just fine ;).

[MRIIOT]

Yea the build produces bootloader.bin, partition-table.bin, ota_data_initial.bin, and micropython.bin. I'll have to use your image tool to take a deeper look.

I'd love to chat if you ever have time. [email protected]

[MRIIOT]

mp-image-tool-esp32 % ls ../builds/v105/3ddecbe 
bootloader.bin          build.txt               micropython.bin         ota_data_initial.bin    partition-table.bin     sdkconfig.combined

mp-image-tool-esp32 % ./mp-image-tool-esp32 ../builds/v105/3ddecbe/micropython.bin
Opening image file: ../builds/v105/3ddecbe/micropython.bin... 
Chip type: esp32 
Flash size: 16MB 
PartitionError: No partition table found.

[glenn20]

mp-image-tool-esp32 works with combined firmware images (or serial attached micropython boards) which aso include a partition table and a bootloader (firmware.bin if you are building your own micropython images). In this case, the micropython.bin is an application image which can be written directly to an ota partition.