Programming/debugging external custom nRF52840 boards using nRF52840 DK

RE: Programming/debugging external custom nRF52840 boards using nRF52840 DK

karujoe1406 — Fri, 18 Apr 2025 07:06:42 GMT

I'll share what worked for me using the newer version of NRF52840 DK.

I am powering the custom board with 1.8V, so the SW10 (VEXT → nRF) switch was switched to ON.

The rest of the connection is as the image below

(NRF DK) VDD NRF' + SWD SEL --------- Custom Board NRF VCC

(NRF DK) SWD IO --------- Custom Board SWD IO

(NRF DK) SWD CLK --------- Custom Board SWD CLK

(NRF DK) External Supply GND --------- Custom Board GND

RE: Programming/debugging external custom nRF52840 boards using nRF52840 DK

Suleman — Wed, 11 Sep 2024 18:03:45 GMT

Hello, i am trying to do the same. i have unsoldered nrf52840 from PCA10056 board and trying to program an external nrf52840 on my custom board. I have made the connections right as board is powering up and showing up on the nrf connect BLE app. I am also able to upload blinky example through the segger embedded studio. But the problem is it is not advertising the BT when uploaded with blinky example. Also on connecting the nrf connect BLE app it shows this error:

RE: Programming/debugging external custom nRF52840 boards using nRF52840 DK

Marx.mz — Tue, 20 Aug 2024 02:06:27 GMT

I've tried this wiring method, but I still can't recognize the external chip, and I use nrf connect for desktop

RE: Programming/debugging external custom nRF52840 boards using nRF52840 DK

Jithu_jo — Sat, 27 May 2023 12:02:16 GMT

Perfect! now it seems to be communicating. Thank you so much.

RE: Programming/debugging external custom nRF52840 boards using nRF52840 DK

filipmrazek — Sat, 27 May 2023 11:20:38 GMT

Hi, yes I solved it. The newer version (the one with nrf53 as a programmer) doesn't use common GND to detect external board is connected. They use common VDD instead. You can see my connection in the image below.

The orange wire is connected from VDD to SWD SEL (to select external board).

My problem was, that I probably used damaged development kit (the LED 5 was not blinking or shining). I tried to use another one and then it worked!

Hope it solves your problem as well.

RE: Programming/debugging external custom nRF52840 boards using nRF52840 DK

Jithu_jo — Sat, 27 May 2023 07:38:06 GMT

Hi Simonr. Can you suggest me what I can do in case my NRF52DK does not have GND DETECT pin

RE: Programming/debugging external custom nRF52840 boards using nRF52840 DK

Jithu_jo — Sat, 27 May 2023 07:37:02 GMT

Hi, were you able to resolve this issue. Neither my nrf52dk has a GND Detect pin

RE: Programming/debugging external custom nRF52840 boards using nRF52840 DK

filipmrazek — Sun, 23 Apr 2023 20:43:55 GMT

Hi!

Have you solved your problem with flashing MS88SF2?
I have exactly the same problem. I'm using nrf52840dk revision 3.0.0 and the P20 connector has different labels than connector mentioned in the first post.

The connector has:
VDD nrf

VDD nrf

SWD SEL

SWD IO

SWD CLK

SWO

RESET

empty

VIN 3-5v

VDD nRF_HV

VDD nRF_HV'

VIO REF

empty

Does anybody know how to connect external board with nrf52840 (MS88SF2) to flash it, please?

Thank you

RE: Programming/debugging external custom nRF52840 boards using nRF52840 DK

matija66 — Mon, 22 Mar 2021 19:52:45 GMT

Hi,

I am trying to program an extrnal nrf52840 it is Minew MS88SF2, I did exactly as desribed above at least I think I did, but unfortunatly it always programs the internal NRF. I measured power supply voltage on external NRF and double cheked connections it seems OK. I am using Mbed Studio.

Do you have any suggestions what else can I try?

Thank you very much.

RE: Programming/debugging external custom nRF52840 boards using nRF52840 DK

Radio — Fri, 31 Jul 2020 07:38:40 GMT

Thanks for the information!!

RE: Programming/debugging external custom nRF52840 boards using nRF52840 DK

Simonr — Thu, 30 Jul 2020 08:27:19 GMT

Yes, the GND_DETECT should be connected to the same GND that your custom board's GND is connected to.

Best regards,

Simon

RE: Programming/debugging external custom nRF52840 boards using nRF52840 DK

Radio — Wed, 29 Jul 2020 07:58:34 GMT

Hi Simonr,

Many thanks for the reply.

I have one more question to clarify. In the link I shared above, they have connected the ground in P1 with GND_DETECT in P20. As shown below.

Do I have to do this in-order to detect an external board?

Thanks a lot!

RE: Programming/debugging external custom nRF52840 boards using nRF52840 DK

Simonr — Wed, 29 Jul 2020 07:51:38 GMT

1. No, the debugger on the DK will detect that an external board is detected and program the custom board instead of the onboard nRF.

2. When you program an external board like this, you should only power the custom board from the DK. You should remove the battery as that is not needed.

3. Yes, you can use this connection method to debug as well.

4. The debugger will not communicate with the onboard nRF on the DK when you have an external board connected like this, so the onboard chip is left to run whatever code was on it from before. It will not affect the debugger or the external board at all.

5. No, the RESET pin is not necessary to connect to the external board.

6. This is one of the ways the DK detects that an external board is connected to the pin header, and knows that the custom board should be programmed, and not the onboard chip.

Best regards,

Simon

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