Using the NRF52840 DK with 1.8V IO

RE: Using the NRF52840 DK with 1.8V IO

RobMeades — Tue, 31 Mar 2020 09:12:16 GMT

Ah, yes, sorry, that's exactly what I had but I had 1.79 V on P21 when it needed more like 1.81 V to work.All sorted now, sorry for bothering you.

RE: Using the NRF52840 DK with 1.8V IO

Simonr — Tue, 31 Mar 2020 09:00:29 GMT

Hi Rob

Please try the following setup: SW10 set to ON. USB connected to J2. SW9 set to VDD. P21 powered from an external 1.8V supply. SW6 set to default.

Best regards,

Simon

RE: Using the NRF52840 DK with 1.8V IO

RobMeades — Mon, 30 Mar 2020 11:27:55 GMT

Thanks, I guess that was where the link was pointing but it doesn't give any more information than the NRF582840 DK user manual already gave me. I have connected 1.8V to the External Supply pins and flipped the VExt->nRF switch to ON but then my debug connection into the USB port J2 no longer works. Have I misunderstood the configuration instructions?

The note in the NRF52840 DK manual in section 8.3.5, and also at that link, says "it is recommended to supply the VDD domain from a different source to prevent the pins of the SoC to be connected to unpowered devices": could that be my problem? If so, how do I go about "supplying the VDD domain from a different source"? Do I just supply 5V to one of the board pins, if so which one?

RE: Using the NRF52840 DK with 1.8V IO

ketiljo — Mon, 30 Mar 2020 11:20:35 GMT

This is described here: https://infocenter.nordicsemi.com/topic/ug_nrf52840_dk/UG/nrf52840_DK/direct_supply.html