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  • Case ID: 287676
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NRf52840 custom board does not work when powered by VBUS and not found by J-link

Vahidreza

Hello everyone 

I have a bunch of custom dongles from the company I work for and two of them started to behave in a strange way after I tried to erase and program them through the PCA10056 board. They all are nRF52840 based dongles. The other dongles which are exactly the same, work with no problem. They all are found with nRF-Connect through PCA10056 and I can erase and program them with no problem.

The issues I'm facing with these two dongles are:

  1. No J-Link can recognize the PCA10056 board when I connect these two dongles, while the other dongles are found with the exact same procedure of wire connecting. before I used to get the Error of "No J-Link Supported Board Found" (or something similar) but now that I updated the j-Link to the latest version I get the J-link dll error.
  2. Both dongles have an application on their flash which work when powered through VDD. But when I power the dongle through VBUS it does not work until I put a voltage on VDD pin. Just a very short pulse on VDD makes the dongle work even when removing the voltage from the VDD pin.

Before giving the VDD pin a pulse (when trying to power the dongle through VBUS), the voltage on VDD is about 0.45V but after the pulse it rises to about 2V.

What can make these dongles behave this way after erasing and programming through PCA10056?

I've updated all the software and utilities to the latest and the OS I'm working on is macOS Monterey 12.3.1

Thank you

Vahidreza

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  • 0 in reply to mytzyiay

    Thanks for your reply

    I did not make any change on UICR in my code personally. But the company sent me HEX file which can erase the whole chip by itself when you program the chip by that. I did that. And I thing what that I did wrong was that I didn't give the chip enough time to be erased completely and interrupted it by removing the power.

    In my circuit VBUS and VDDH are short-circuited so that here it looks like that the problem is that the dongle does not work in High Voltage mode until it is powered up in low voltage mode. VDD and DCCH are short-circuited as well and the voltage measured on these pins on one of the malfunctioning boards are as below:

    1. when putting 2.94V on VDDH the voltage on VDD (and DCCH) is 0.44V and when I give a very short pulse of 2.98V to VDD, the voltage on this pin is remained on 2.7V and the dongle works.
    2. when putting 5v on VDDH the voltage on VDD (and DCCH) is 0.45V and by giving a pulse as explained above the dongle starts working.
    3. when putting 2.98V on DVV the voltage on VDDH is 2.71V and the dongle works.

    In one of the good boards that I measured, when putting 2.97V on VDDH the voltage on VDD is 2.94V and the dongle works without the need of that pulse.

  • 0 in reply to Vahidreza

    Not sure, but I would check:

    • If you're using high voltage mode and you don't have the LC circuit on DCCH, make sure the regulator (DCDCEN0) is configured to use LDO mode rather than DC/DC mode
    • In high voltage mode, VDDH needs to be at least 0.3V higher than VDD. What voltage is your VDD configured for, anyway?  It looks like that voltage is not correct even after applying the pulse?
    • Some more hints in https://devzone.nordicsemi.com/f/nordic-q-a/76855/nrf52840-high-voltage-mode-specs
  • 0 in reply to mytzyiay

    DCDC is disabled and there is no configuration for the VDD voltage. So the values are as defaults.

    I wish I knew what exactly happens after that pulse? Why the pulse is needed? I thought the internal regulator is damaged, but if it is that way, how does it work after the pulse? 

    As I mentioned, I'm not able to program the dongles as no J-Link can find them. What should I do about that? 

    Can the voltage cause the issue? if YES so how the other dongles are working without a problem? 

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