Unable to program external nRF52832 custom board using nRF52840 DK (P19 Debug Out)
I am trying to program an external custom board based on the nRF52832 SoC using the nRF52840 DK as the SWD programmer.
I followed the official Nordic documentation for using the DK’s Debug Out header (P19):
https://docs.nordicsemi.com/bundle/ug_nrf52840_dk/page/UG/dk/hw_debug_out.html
Here is what I have done so far:
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Connected SWDIO, SWDCLK, RESET, VTG (3V), and GND from P19 on the DK to the corresponding pins on the custom board.
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Verified VTG is 3.0 V on both DK and target board.
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Shorted SB47 to allow the DK to power the external board.
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The external board’s reset line is connected to the DK’s reset.
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The SWDIO/SWDCLK lines have continuity and are correctly wired.
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The DK is detected normally by
nrfjprog --ids.
Issue:
Even after wiring according to the documentation, only the nRF52840 on the DK gets programmed. The external nRF52832 is never detected by nRF Connect or nrfjprog.
However, within VS Code → nRF Connect → “Connected Devices,” I actually see two devices listed: the DK and the external board. So it appears that something is being detected, but programming still targets only the DK.
Question:
Given that the external nRF52832 shows up in the VS Code device list, what could cause the DK to still program only its onboard SoC? Are there additional jumpers, SB pins, or configuration steps required to ensure P19 Debug Out is used as the programming target?
Any guidance or troubleshooting steps would be greatly appreciated.
