Setup ESP32 JTAG-Debugging on PlatformIO with a J-Link debug probe

Following the instructions of the PlatformIO documentation (Get started with Arduino and ESP32-DevKitC: debugging and unit testing and J-LINK), I tried to setup my development environment.

Here is how I got it up and running:

1. Download and install the J-Link software and documentation pack.
2. Download and install the Zadig tool to modify the USB driver of the J-Link (thanks manuelbl).
   1. Run Zadig.exe
   2. Options > List all devices
   3. Select BULK interface (Interface 2)
   4. Change Driver from jlink to WinUSB > Replace Driver
3. Setup a new PlatformIO project in VS Code according to the docs.
4. Modify the platformio.ini:

    [env:esp32dev]
    platform = espressif32
    board = esp32dev
    framework = arduino
    debug_tool = jlink
    upload_protocol = jlink
   

   The upload_protocol is important, it must be “jlink” not “jlink-jtag” as stated in the docs (thanks lumax).

5. Start debugging by pressing F5 and have fun debugging your Arduino ESP32 project via JTAG.

Troubleshooting

LIBUSB_ERROR_NOT_FOUND

Replace the jlink USB-Driver with WinUSB (see step 2 above).

“Error: JTAG scan chain interrogation failed: …”

Double check your wiring, seriously!!!

It should be like this:

J-Link	ESP32	Description
1	VCC (3v3)
4	GND
5	TDI (D12)	Test Data In
7	TMS (D14)	Test Mode State
9	TCK (D13)	JTAG Return Test Clock
13	TDO (D15)	Test Data Out
15	RESET (EN)	(active low) reset input of the target

F5 -> Could not find the specified task.

If you go to the Debug view, there is a green arrow at the top left of the window, labelled RUN AND DEBUG. Next to it, there is a combo box. The combo box should say PIO Debug (your project name).

Thanks manuelbl!