nrf52840DK is not getting powered up

RE: nrf52840DK is not getting powered up

Amanda Hsieh — Mon, 31 May 2021 07:43:45 GMT

Hi Vishnu Sukumaran,

Please send me a private message with your e-mail address. Thanks.

-Amand H.

RE: nrf52840DK is not getting powered up

Vishnu Sukumaran — Mon, 31 May 2021 06:02:17 GMT

Yes, I have tried both. Couldn't find any difference.

RE: nrf52840DK is not getting powered up

Amanda Hsieh — Thu, 27 May 2021 13:16:08 GMT

Have you tried different usb cables and PC usb ports?

-Amanda H.

RE: nrf52840DK is not getting powered up

Vishnu Sukumaran — Thu, 27 May 2021 09:15:12 GMT

Hi Amanda,

On the sticker it is mentioned - PCA10056, 2.0.0, 2019.47

RE: nrf52840DK is not getting powered up

jeevan t raj — Thu, 27 May 2021 08:57:57 GMT

Hi Amanda,

Thanks for the reply. It really helped. We will take care of the pull-down as you mentioned.

I can continue the development activities by doing this workaround in my DK.

RE: nrf52840DK is not getting powered up

Amanda Hsieh — Thu, 27 May 2021 08:52:06 GMT

Hi Vishnu,

What is the HW version on the white sticker?

-Amanda H.

RE: nrf52840DK is not getting powered up

Vishnu Sukumaran — Wed, 26 May 2021 15:42:56 GMT

Hi Amanda,

I too have exactly same issue with the nRF52840-DK. My board is taking even longer time to power ON. Today it took more than 6 hours to power ON. Shorting TP33 to the ground doesn't seem to work in my case. The voltage readings at the test points are as mentioned below. Please note that the resolution of the voltage readings are not up to decimal places.

When the board is not powered up (limbo state)

TP28 - 4V
TP36 - 4V
TP29 - 0V
TP35 - 0V

When the board is up (normal state)

TP28 - 4V
TP36 - 4V
TP29 - 2V
TP35 - 2V

Earlier, once the board had powered ON, the subsequent power up-s were quick. Today, the situation has got even weirder. The board had powered ON successfully with relatively lesser time. The subsequent power ON took more than 6 hours. Please look into the issue and suggest any workaround.

RE: nrf52840DK is not getting powered up

Amanda Hsieh — Tue, 25 May 2021 07:11:22 GMT

Hi Jeevan,

There is something strange here:

TP28: This should be USB voltage minus a small diode drop, so ~4.5V
TP36: Is on the output of the boost regulator, so this should be 5V
TP29: Is the output of the buck regulator and the "VREG enable" load switch, this should be 3V
TP35: Is the power to the Segger, this should be 3V.

It's hard to say exactly where in the chain things go bad since it is the same behavior when powering externally, but that it works when TP33 is grounded it leads me towards issues with the voltage follower.

Grounding TP33 is not a problem as long as the SW9 is in the VDD position, any other position would then short the VDD_nRF to GND. A better alternative would probably add a pull-down to TP33, 1MOhm or 100kOhm.

-Amanda H.

RE: nrf52840DK is not getting powered up

jeevan t raj — Fri, 21 May 2021 06:50:15 GMT

Amanda,

Adding one more observation.

Even the board turned ON gradually, the voltages are found changing in TP 28, 36, 29. But the TP35 now measures 1.2-1.5V

RE: nrf52840DK is not getting powered up

jeevan t raj — Fri, 21 May 2021 06:05:03 GMT

Hi Amanda,

I had probed the TP's. The voltage is found fluctuating, not a constant value.

TP28 - 3.3 - 3.8v
TP36 -   3.3 - 3.9v
TP29 -   1.2 - 1.7v
TP35 -   0 - 0.2v

When I shorted the TP33 to the GND board started up immediately and working properly. But when I removed that jumper wire it turned back to off.

RE: nrf52840DK is not getting powered up

jeevan t raj — Thu, 20 May 2021 13:13:35 GMT

Hai Amanda,

Thanks for the reply.

Today morning also had the issue. I kept the board powered ON from the morning. By around 1 pm, it turned up and started working as normal. Still, now I am working on it.

Most probably I shall get the issue tomorrow morning after the board rested completely for today's night.

I will try the probing and shorting as you said and inform you about the readings/observation.

RE: nrf52840DK is not getting powered up

Amanda Hsieh — Thu, 20 May 2021 13:03:05 GMT

Hi Jeevan,

Could you have some voltage levels on some testpoint when it is in this "limbo" state?

It would be interesting to see the voltage on:

TP28
TP36
TP29
TP35

Maybe you could try to short TP33 to GND briefly and see if that "jump starts" the board.

-Amanda H.

RE: nrf52840DK is not getting powered up

jeevan t raj — Wed, 19 May 2021 13:01:44 GMT

Hi Amanda,

Yes, SW6 is in DEFAULT position(Right) and SW9 is in VDD position(middle).

RE: nrf52840DK is not getting powered up

Amanda Hsieh — Wed, 19 May 2021 12:59:24 GMT

Hi Jeevan,

Please check that SW6 is on the DEFAULT position and SW9 is on the VDD position as the figure.

Let me know this can help or not. Thanks.

-Amanda H.