ESP32 - JTAG flashing and debugging

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Joined: Mon Jun 10, 2019 2:45 pm

ESP32 - JTAG flashing and debugging

Postby Paul85 » Mon Jun 10, 2019 4:02 pm


I'm really new with ESP32 and I'm designing a custom board based on ESP32-WROOM-32D.
By reading the documentation I cannot understand if for mass-production it is possible flashing the FW by using only an external JTAG programmer (Uart0 and download boot will be disabled).

- If yes, can I use Segger J-link emulator and which one? is it compatible with OpenOCD?
- What other commercial emulators can I use?

Thanks :)

Posts: 1460
Joined: Tue Dec 01, 2015 8:37 am

Re: ESP32 - JTAG flashing and debugging

Postby ESP_igrr » Mon Jun 10, 2019 6:12 pm

Hi Paul85,
It is possible to flash the application using JTAG, if the application loaded into the module does not disable or reconfigure JTAG pins.

Some versions of the AT application shipped by default on WROOM/WROVER modules do reconfigure JTAG pins as SPI slave pins. If the module comes with such application, then you will need to erase it using UART download mode first, before JTAG can work.

Also note that some production related features (such as burning and reading EFUSEs) are currently only implemented over the UART download mode.

Regarding hardware: JLink works fine with OpenOCD, but is usually slower than FT2232H based adapters. Some FT2232H based adapters are Olimex ARM-USB-TINY-H and TinCanTools Flyswatter 2.

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