Getting 3.3V on VDD on a nrf52840DK, is it possible?

[jsantosrico]

I'm using the nrf52840DK to power our external target board. I've noticed that the VDD level in a nrf52840DK is 3V, and not 3V3. This might be enough to throw our board off some of the times (but not always).

I believe it's possible to get it to output 3V3, based on this thread ( nRF52840 DK v3.0.0: VDD vs VDD_nRF)

In any case, in that thread, it's mentioned that some stuff needs to be added to the interface FW, but I can't find that FW anywhere (there's a binary for the SAM chips on DK of older versions, but we are using v3 DK, that have a Nordic soc as interface chip). Can I get the steps to get the DK in a mode were VDD outputs 3V3?

Thanks!

[Simonr]

Hi

As Priyanka says in the case you linked to, the GPIO levels will be equal to the level on the VDD pin, and due to the voltage regulators on the DK, the VDD will always be running on 3V if powered by the USB that goes through the debugger chip on the board. You need to change the power supply to either the external powre supply P21, the Li-Po connector (J6), or the USB connector (J3) and then power VDD with 3.3V, which i guess is not possible from the USB connector. Note that the VEXT->nRF swich (SW10) should be set to ON, and the nRF power source (SW9)m switch should be set to whatever you're using for powering it.

We don't have any firmware to change the interface firmware on newer revisions of the DK I'm afraid.

Best regards,

Simon

[morgan_moon]

When powering with an external 3.3V source, how do I use a USB connection for serial/debugging? I have the dev board running fine with the "External Source" pins but as soon as I plug in USB for debugging it pulls all my I/O to 3.0V, which causes my UART peripherals to stop working. I have SW10 ON, SW9 VDD, 3.3V external to External Source and VDD.