Hello,
I am trying to flash the nRF52840 SoC on the nRF52840 DK using an external J-Link debugger, without relying on the interface MCU or the onboard J-Link. My current switch settings are as follows:
- SW6: nRF ONLY
- SW8: ON
- SW9: USB
- SW10: OFF
I have connected a USB cable to the J3 port (nRF USB), but no LED lights up.In this configuration, I connected the external J-Link debugger to the Debug IN port (P18) as follows:
- J-Link → P18
- VTREF → Pin 1
- SWDIO → Pin 2
- GND → Pin 3
- SWCLK → Pin 4
- NTRST → Pin 7
When I try to connect using JLinkExe, I get the following messages, and the connection fails:
Device "NRF52840_XXAA" selected.
Connecting to target via SWD
InitTarget() start
InitTarget() end - Took 105ms
Failed to attach to CPU. Trying connect under reset.
InitTarget() start
InitTarget() end - Took 112ms
Cannot connect to target.
Additionally, when I open the nRF Connect Programmer app and select the external J-Link, I see this error:
Failed "reading readback protection status for application core".
Error: code: 1, description: Generic, message: Batch task protection-get failed,
[Probe] Emulator error: No emulator with connection info 'Usb(JLinkSerialNumber(941000024))' was found
Am I missing something in my configuration? How can I resolve this issue?Although I am currently working on the nRF52840 DK, I plan to use the nRF52840 SoC on a custom board with another MCU in the future. Therefore, it is essential for me to understand how to flash the SoC using an external J-Link.
UPDATE:
I deleted latest J-Link driver, then I installed J-Link driver version 7.94i.
Then, I got another Error Message on nRF Connect Programmer.
Failed "reading readback protection status for application core". Error: code: 1, description: Generic, message: Batch task protection-get failed, [Probe] Device error: Failed to write DebugPort register 2: Unknown Error in J-Link DLL (error code =-1)
