Updating ESP32 firmware from another ESP32 over USB, similar to how esptool.py works

Question

Is there a way to update the firmware on one ESP32 from another ESP32 over USB, similar to how firmware can be updated using esptool.py?

This would essentially be like a port of whatever magic esptool.py uses over USB to update an ESP32, but instead of running through Python it would be an Arduino C++ sketch and would read the firmware to write to the other ESP32 from SPIFFS.

• Juraj: since ESP32 doesn't have an USB peripheral on chip, a better idea would be to that over the UART. did you research before asking? did you find something? did you try something?
• Dan: Thanks for sharing your opinion, @Juraj. However, all of the ESP32s that I am working with include a CP2102 USB to UART bridge.
• Juraj: can CP2102 act as USB host? no.
• Dan: That's a great point, @Juraj
• Juraj: you know that you can use OTA upload?

Answer 1

To flash an ESP32 using another ESP32:

Enter Bootloader Mode: Pull the BOOT_PIN of the target ESP32 LOW and toggle the EN_PIN to reset it, placing it in bootloader mode. Sync with Bootloader: Send a SYNC command from the master ESP32 to establish communication. Configure Flash: Use the SPI_ATTACH command to prepare the target’s flash memory. Initialize Flashing: Send a FLASH_BEGIN command to specify data size, memory location, and block sizes. Transfer Firmware: Send firmware in small chunks (e.g., 1 KB) using FLASH_DATA, with checksums for accuracy. Complete Flashing: Use the FLASH_END command to finalize. The target ESP32 can reboot to run the new firmware. I’ve created a library to streamline this process. You can find it here: Flashing Firmware to an ESP32 Using Another ESP32.

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Answer 2

Espressif has an official library. Here's the link:

https://github.com/espressif/esp-serial-flasher

Personally, I recommend this GitHub repository named "FlashBox - Esp32 serial flasher" by Machiel80. Here's the link:

https://github.com/Machiel80/esp32-serial-flasher

it has good documentation and even a video on YouTube explaining how it's done.

Finally, the flipperZero project also has a serial flasher project on Github, the "flipperzero-esp-flasher". Here's the link:

https://github.com/0xchocolate/flipperzero-esp-flasher

Answer 3

You can use the SD card to update the firmware. Here is the example code