Flashing an ESP32 with another ESP32

[gunar.kroeger]

We have 2 esp32 connected through UART. Let's call them esp32A and esp32B.

esp32A has a SD card connected with the firmware.bin for esp32B.
esp32A also has connection to the reset and boot pins of esp32B. How can I port the protocol implemented by esptool.py to flash firmware.bin into esp32b? the simplest way is OK, so compression and encryption are not needed right now.

I'm using esp-idf-v3.3.
Has anyone done this before?

Thanks

[PeterR]

Hi,
Yes, we have done this. I am waiting for commercial to agree open sourcing.

Alternatively ESP_igrr suggested:

On the ESP32 side, you can use UART driver and esp_ota APIs. See system/ota/native_ota_example example. This example downloads the firmware from a remote server, but same APIs can be just as well used to implement OTA over UART or over SPI.

Which would seem a better route. Just remember to protect your bootloader from update.

[gunar.kroeger]

Hi @PeterR,

If you could send your source it would help a lot!

We are already working on a solution based on the OTA example, but being able to flash the espB without it having any firmware on it would be more flexible and would speed up production as well.

Please let me know if you can send me the source you mentioned.

[PeterR]

Ok, will do, it may be a long burn - you know commerical.
Yes, I took the same view initially however if you use Ethernet you need to be careful with the clock circuit.

You can also get chips pre-programmed if that helps.

[NathanJPhillips]

Hi @PeterR, do make sure you post here if you ever get permission for this. Also, could you explain your comment about the clock circuit?

cheers, Nathan

[NathanJPhillips]

This seems a long time ago now, but just stumbled on my old post - for anyone else who needs the same I reimplemented this in the end based on https://github.com/espressif/esp-serial-flasher.

[dmitry-rdflex]

This seems a long time ago now, but just stumbled on my old post - for anyone else who needs the same I reimplemented this in the end based on https://github.com/espressif/esp-serial-flasher.

Thank you!