Programming external module over SWD using nrf7002dk

RE: Programming external module over SWD using nrf7002dk

Simon D-M — Wed, 09 Sep 2026 11:26:41 GMT

Hi,

If you want to be on the safe side, you can continue using RTT if it works fine for you. If you want to use the VCOMs, I think you can use the p20 header as there is no "1.8V domain" anymore as the VDD has been raised to 3V. All the chips (IMCU, nRF5340 and nRF7002) are now using 3V as their VDD.

But if you do this, be sure to not have the onboard nRF5340 trying to control the UART you are trying to your with your external board at the same time.

Also, be careful about the startup sequence as if the VIO_REF is set to 3V after the communication has started, you may still break some stuff as there will be some voltage mismatch.

Best regards,

Simon

RE: Programming external module over SWD using nrf7002dk

ccdev — Tue, 08 Sep 2026 15:48:30 GMT

I was debating with myself if that would work! I was hesitant to try it because it doesnt mention it in the 7002dk docs, it just says "the external module must match the 1.8 dk".

FYI: i actually successfully flashed without the vio_ref, but any code related to the wifi didnt work, probably because my module requires ~3v for wifi (vbat70) and the dk p20 pin2 is only supplying 1.8v, which makes sense.

Im going to try powering the module externally at 3v and sending the same 3v into the vio_ref tomorrow, as you suggested.

Got a suggestions on the cleanest way to get the console output from my module? Once i send the external 3v to vio_ref, is it also safe to connect the gpio tx pin on my module to the p0.22 on the dk, so i can see printk() logs from my module uaing the vcom in vscode? Im guessing no, because the p0.22 is not part of the p20 header, so i would be sending 3v into the 1.8 domain.

Maybe i ought to go directly from the gpio tx pin on my module to a uart/usb connector straight into my mac if i want console output from the module? Or should i just use RTT (which currently works)

Thanks for the fast reply btw!

RE: Programming external module over SWD using nrf7002dk

Simon D-M — Tue, 08 Sep 2026 13:07:04 GMT

Hi,

As you said the nRF7002 DK VDD is by default 1.8V. However, it is possible to set that VDD to a different voltage. To do this you can use the VIO_REF pin. There is a follower circuit that will make the VDD follow this voltage (of course you cannot go above the DK power supply voltage, which is most likely 5V if the DK is powered through USB).

So in your case, if you need 3V on your custom board, you have to input a constant 3V signal to the VIO_REF pin. And then you can use the IMCU from the nRF7002 to program and debug your custom board.

Best regards,

Simon