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  • Case ID: 329138
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GPIO output voltage 2.46V

Ivo H

Dear sir or madam,

I am facing a peculiar issue. In my application, I am using nrf52840 dongle and I am setting several GPIO pins as output pins with output value high that means approximately 3V .. 2.96V

The majority of set pins have the output voltage value of 2.96V, but only one pin (GPIO 0.13 the first pin on the right side from USB view) has the value of 2.46V, I would be fine with that, but it is recognized as output low and logical low in my application instead of logical high. It seems like pin 0.13 is still functional as I can toggle it to 0V and back to high state, but it still yields 2.46V

If I burn the firmware to another nrf52840 dongle, the same pin (0.13) has voltage 2.96V as expected. So I suspect the problem is on a hardware side.

But could anyone explain me this issue? Could there be some kind of voltage leakage or downlead which causes this issue?Is there any way how to fix it?

We planned to heat the board so that any cold solder join could dissappear, but we would rather wait for advice. Apart from soldering a header to pins we did not do any change to the hardware. It is standard Nordic manufactured NRF52840 dongle.

Thank you

Ivo

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  • 0

    Hi,

    Could you check the board to see whether there is any damage to any pins or traces or solders? 

    Also, could you try to measure the resistance to ground from pin 0.13 on the damaged dongle in order to check for any short circuit?

    You could also measure the current draw at P0.13 on both dongles to compare.

    Regards,

    Priyanka

  • 0 in reply to Priyanka

    Thank you for your reply. I measured the resistance on the suspicious pin and the resistance is 0.5 mega Ohm compared to the other ones readings which are 0.8 mega Ohm on every working pin.

    I also checked the board but there are no signs of traces or solder remains which could possibly ground the pin at least they are not visible on the naked eye.

    If the pin could still be turned on and of, what do you think the cause of malfunctioning could be? I checked the PCB of 52480 dongle and it seems like the GPIO castellated pins are connected directly to the CPU so either there is a problem inside the chip or there is a problem with the route from the CPU to the pin.

    I don't think there is a voltage drop across any resistor since we measured lower resistance and due to the fact we measured lower output voltage, it could be caused by some leakage to the ground or if there is a transistor inside the CPU then the transistor could be harmed causing higher internal resistance when the transistor is opened, just guessing.

    I am asking myself whether we did not apply to much heat when removing previous header with a new one as we definitely touched the pin 0.13 with heat fan as well as heat tip.Is there a temperature limit we definitely should not exceed?

    Actually would be nice to get to know a bit more about 52840 and as icing on a cake to possible repair the pin.

  • 0 in reply to Ivo H
    Ivo H said:
    I am asking myself whether we did not apply to much heat when removing previous header with a new one as we definitely touched the pin 0.13 with heat fan as well as heat tip.Is there a temperature limit we definitely should not exceed?

    Please take a look at the recommended operating conditions, where the required temperature range is mentioned.

    -Priyanka

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