nrf52833(QFN) cannot be flashed. cannot debug.

RE: nrf52833(QFN) cannot be flashed. cannot debug.

Ressa — Thu, 09 Apr 2026 11:31:57 GMT

RE: nrf52833(QFN) cannot be flashed. cannot debug.

nick yong — Wed, 08 Apr 2026 16:53:08 GMT

for QFN40 NRF52833.
the swd and swclk is specific pin (19,20)
and the reset pin is P0.18/reset (16)
is it true?
I should make sure this is right.

RE: nrf52833(QFN) cannot be flashed. cannot debug.

Ressa — Thu, 11 Sep 2025 09:20:31 GMT

Hi,

By SWD0_SEL I mean the below pin on Debug out connector of nRF52833 DK:

It should be connected to the ground on your target board (your own board). By doing that, DK can recognize that there is an external board connected to the DK.

RE: nrf52833(QFN) cannot be flashed. cannot debug.

nick yong — Thu, 11 Sep 2025 05:05:47 GMT

the third party board (works well) have no 32k oscillator either.
Pin 3 (SWD0_SELECT). what do you mean by Pin3? I cannot find any pin in the QDAA chip

and I do not change any thing when I try third part board(works well QIAA) and my own board(QDAA)
for the reset pin, I make it unconnected.

RE: nrf52833(QFN) cannot be flashed. cannot debug.

Ressa — Mon, 08 Sep 2025 08:15:35 GMT

Hi,

Thanks for clarification. So you have one board (bought from different company) that works fine in all situation , is that correct? Does this board have 32kHz oscillator ?

Also for programming a custom board using DK debug out port, the minimum connections are as follow: pins 1 (VTref), 2 (SWDIO), 4 (SWDCLK), and 5 (GND).
*Pin 3 (SWD0_SELECT) is used for debug out selection and should be connected to GND on the target board for proper operation on some DKs.
*For reliable operation, also connect pin 10 (RESET) if available.

If you cannot add an external 32kHz crystal to your boards, then try to change the configuration to use internal 32kHz crystal. in your prj.conf make sure to have below lines:

CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y CONFIG_CLOCK_CONTROL_NRF_K32SRC_XTAL=n

Also if the board is unresponsive try to recover it by this command:

nrfjprog --recover -f nrf52

or

nrfutil device recover --serial-number <SERIAL_NUMBER>

and find serial number with:

nrfutil device list --traits jlink

Best regards,
Ressa

RE: nrf52833(QFN) cannot be flashed. cannot debug.

nick yong — Sat, 06 Sep 2025 02:17:11 GMT

I use 52833 DK as debugger. (my board have no 32k osc)
connet my own board by (swd swclk vcc gnd) (4 lines). it works well on other 52833 board( I buy from other company)
I try all the 5 board. they have the same issue:
at first try, It will run into main function. I cannot find any issue.
and afterwards. I try and try, but it cannot run into main function. it looks it loss the connect to the board.

another board have such problem: flash ok. but loss connection immedialtely.

flash image done, but loss connection with no error.

RE: nrf52833(QFN) cannot be flashed. cannot debug.

Ressa — Fri, 05 Sep 2025 12:32:54 GMT

Hi,

Can you share a schematic or drawing which pins are connected to the programmer? If you are supplying the target board separately, then you need to provide the VDD supply of the board to the programmer as well (VTref).

If your custom board does not have a 32.768 kHz crystal but the firmware after first time programing expects it, the app can hang in standalone mode but can run under debugger.

Best regards,
Ressa