nRF52840-DK where is VIO_REF pin

[Chuan]

My board nRF52840-DK always take several minutes to be ready after plugging usb cable in. The issue like Markus described in this ticket:

https://devzone.nordicsemi.com/f/nordic-q-a/84620/j-link-from-nrf52840-dk-takes-several-minutes-to-come-up-when-not-connected-for-a-longer-time/352462

I see that connecting pin VIO_REF to GND will solve the issue.

But I can't find the "VIO_REF on P20" on my nRF52840-DK board, could someone please show me where that pin?

About my nRF52840-DK board, I see the pins layout of P20 on my board same as document: nRF52840 DK v1.0.0 - User Guide

[Kenneth]

I were not able to get hold of the one that designed the board, but can you try to place a ~10kohm resistor on R88 (close to TP33 and RESET pin on header P20). If that doesn't help, what are the switches on the DK set to?

Kenneth

[Chuan]

Hi Kenneth

The surface of R88 is too small and I can't solder a resistor to it with my equipments.

But when I try to put a 10kohm resistor to R88 by hands, it seems to work because I see the led bright, actually it blinks, may be by connected point is not stable.

When I try to ground TP33 to GND (it easy to make the connected point stable), the board works well. Is this way ok?

Thanks

[Kenneth]

Chuan said:

When I try to ground TP33 to GND (it easy to make the connected point stable), the board works well. Is this way ok?

It likely will work as long as you don't plan to connect any third party board for programming, then I suspect you will short gnd to vdd if you don't use a resistor.

Kenneth

[Chuan]

Hi Kenneth,

I made a misunderstood. I mean put a 10kohm resistor between TP33 and GND. Is it ok ?

Thanks

[Kenneth]

Chuan said:

I made a misunderstood. I mean put a 10kohm resistor between TP33 and GND. Is it ok ?

Ah, That is fine yes.

Kenneth

[Chuan]

Great, thanks for your help!