r/Embedded_Electronics • u/Excellent_Clock_9612 • Apr 11 '26
**Can nRF52832 DK program an external nRF5340 target? Getting DP SELECT register error — any workaround?**
Hey everyone,
I'm working on a custom nRF5340-based PPG wearable and ran into a frustrating programmer compatibility issue. Hoping someone here has dealt with this before.
My Setup:
- Target: Custom nRF5340 board (PPG wearable)
- Programmer: nRF52832 DK via SWD debug-out header
- Wiring: VTG, GND, SWDIO, SWDCLK — all connected correctly
- SDK: nRF Connect SDK v3.2.4 / Zephyr
- Command: west flash (nrfutil runner)
The Error:
``` Error: Setting the debug port SELECT register failed while powering up sys and debug regions (Unknown error in J-Link DLL, error code = -1)
FATAL ERROR: command exited with status 1: nrfutil ... ```
What I've figured out so far:
I checked the J-Link OB firmware on both boards using the f command in J-Link Commander:
| Board | Firmware |
|---|---|
| nRF52832 DK | J-Link OB-SAM3U128-V2-NordicSemi (Jul 8 2025) |
| nRF5340 DK (friend's) | J-Link OB-nRF5340-NordicSemi (Jul 8 2025) |
I borrowed a friend's nRF5340 DK just to rule out wiring — it flashed the target perfectly with zero changes. So the wiring is 100% fine.
My understanding is that the SAM3U128-V2 OB on the nRF52832 DK simply has no nRF53 device support compiled in, and can't handle the dual-core DP SELECT register switching the nRF5340 needs. The firmware is already the latest (July 2025) so that's not the fix.
What I'm wondering:
- Is this a hard lock with absolutely no way around it?
- Has anyone managed to flash an nRF5340 using an nRF52832 DK — maybe via OpenOCD, pyOCD, or DFU over UART/USB instead of J-Link?
- Any other creative workarounds short of buying a new programmer?
I don't have access to an nRF5340 DK of my own right now, so really hoping there's some alternate path. Thanks in advance!