RayTac mdbt42q-p512kv2 programming issue with custom board

[AhmetSafi]

I'm trying to program a custom board with a Raytac nRF52832 module using the nRF52 DK's onboard J-Link via the P20 debug out port. The J-Link only detects the onboard nRF52832, not my external module.

I've checked the following:

• My custom board is powered with a solid 3V.
• The module's DEC4 pin shows 1.234V, so its internal regulator is working.
• All P20 connections (GND, SWDCLK, SWDIO, RESET) are wired correctly per the DK user guide.
• The P20 VTG pin is correctly connected to my board's 3V supply.
• The P19 debug out port is completely empty.

To verify my board, I connected an ST-Link v2 with OpenOCD, and it successfully detected the chip. The log shows:

❯ openocd -f interface/stlink.cfg -f target/nrf52.cfg

Open On-Chip Debugger 0.12.0

Licensed under GNU GPL v2

For bug reports, read

        openocd.org/.../bugs.html

Info : auto-selecting first available session transport "hla_swd". To override use 'transport select <transport>'.

Info : The selected transport took over low-level target control. The results might differ compared to plain JTAG/SWD

nRF52 device has a CTRL-AP dedicated to recover the device from AP lock.

A high level adapter (like a ST-Link) you are currently using cannot access

the CTRL-AP so 'nrf52_recover' command will not work.

Do not enable UICR APPROTECT.

Info : Listening on port 6666 for tcl connections

Info : Listening on port 4444 for telnet connections

Info : clock speed 1000 kHz

Info : STLINK V2J45M31 (API v2) VID:PID 0483:374B

Info : Target voltage: 3.263684

Info : [nrf52.cpu] Cortex-M4 r0p1 processor detected

Info : [nrf52.cpu] target has 6 breakpoints, 4 watchpoints

Info : starting gdb server for nrf52.cpu on 3333

Info : Listening on port 3333 for gdb connections

Questions:

1. Since the ST-Link works, is there a special nrfjprog or nrfutil command other then "recover" needed to force the DK's J-Link to use the P20 port? I tried vs code board recover and nrf tool recovering but it did not help.
2. If I give up on the DK, will a J-Link EDU Mini work correctly with a 3V (not 3.3V) target board? I will buy j-link edu if it will work.
3. Can I recover chip with using ST-link?

Document1-20251104125702.pdf

[AhmetSafi]

I have an update on my issue. I successfully managed to program my custom Raytac board using an ST-Link v2 and OpenOCD.

I was able to erase the chip with this command:
openocd -f interface/stlink.cfg -f target/nrf52.cfg -c "init" -c "halt" -c "nrf5 mass_erase" -c "reset exit"

And I successfully flashed my merged.hex file with this command:
openocd -f interface/stlink.cfg -f target/nrf52.cfg -c "program merged.hex verify reset exit"

For my prj.conf, I'm using these clock settings:
CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_500PPM=y
CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC_CALIBRATION=y
CONFIG_CLOCK_CONTROL_NRF_CALIBRATION_LF_ALWAYS_ON=y

I used these lines because my board does not have an external crystal oscillator and I must use the internal RC oscillator.

I still don't know why the onboard J-Link on my nRF52 DK wouldn't work, even with the P19 port empty. If you see any mistake I might have made in my DK setup, please let me know. It's a bit difficult to debug this way (with OpenOCD) since there is no Virtual COM port.

Thanks for help in advance.

[Amanda Hsieh]

You can refer to this post for the connection and check by the J-Link Commander, also answer the questions in my previous reply. Please also provide a picture to show how you connect the custom board to the nRF52 DK.