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nRF9160 reset issue

Grigor

Hi.

We have developing a IoT board based on nRF9160 and faced some strange issue.

We have realized the reset schematic of nRF9160 in this way

The nRESET pin is pulled-up by 10kOhm which has been changed to 1kOhm and for both cases we have 2.2V on nRESET pin. The other end of this pin connected to GPIO of nRF52832. The GPIO configured as output and programmatically set to HIGH.

When we are connecting the board to nRF9160-DK for programming nRF9160 on our board the SDK can't detect nRF9160 and program. When we are connecting nRESET directly to 3.3V nRF9160-DK can detect and program without any issue.

I tried to measure the voltage for the same pin of nRF9160 on nRF9160-DK and the voltage there also was 2.2V but we can detect and program built-in nRF9160 on DK.

We tried to disconnect nRESET pin from nRF52832 but there were no any changes neither voltage level on nRESET pin nor on operation.

I tried to measure current, going from nRESET to 3.3V during dirrect connection and it was around 13mA, which I thing too much.

The nRF9160 full part number is nRF9160-SICA-B0,  1920AL


Does anyone had a similar issue?

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  • 0 in reply to Andreas

    Hi Andreas.

    Currently we have disconnected nRESET from both pull-up resistor and nRF52832 GPIO.

    Even in this case we can't program or detect nRF9160. We can only program and detect nRF9160 when connecting to 3.3V directly.

    It's not working in case if we connecting to nRF52832 and driving this pin to "HIGH".

    Thank you .

  • 0 in reply to Grigor

    Hi,

     

    This sounds a little strange, I will have to look into it and get back to you. Just for my reference, how many boards have you verified this occurrence in? Also, I assume that in the 'not able to program' state, the loaded FW is also not running (i.e. nRF9160 stuck in a reset state)?

     

    Best regards,
    Andreas

  • 0 in reply to Andreas

    Yeah,

    Actually it's strange issue, because we have developed more than 7 boards and produced more than 50 samples and this is first time we are facing the issue.

    The most strange thing, is, that the same voltage exist in nRESET pin on nRF9160-DK but it's working.

    Also, 'not able to program' I men, that nRF connect software can't detect nRF9160 module for programming. But once we are connecting nRESET pin to 3.3V we can program the device and it's working without any problem.

    For this design it's the first board but we had a lot of boards with similar schematic and all were working perfectly.

    I would expect, that either this nRF9160 is faulty or this batch of nRF9160 have some errata.

    Regards,

    Grigor

  • +1 in reply to Grigor

    Hi Grigor,

    It sounds to me that the nRF9160 is damaged. Please note that the internal voltage in the nRF9160 is 2.2V and this is also the nRESET active voltage. By pulling it to 3.3V you might damage the circuitry inside the nRF9160.

    What is the VDD voltage on the nRF52832? It should be within 2.2V +/- 0.3 V. For setting up the GPIO which is connected to nRESET use S0D1 (standard drive low, and disconnect high) It will pull the reset to 0 for resetting, and allow the internal pullup on 91 to pull it back up to 2.2V when active.

    Stian

  • 0 in reply to Stian Røed Hafskjold

    Hi Stian,

    Thank you for your reply.

    Yeah, I think this part of nRF9160 has been damaged, but what is interesting, when we are connecting it directly to 3.3V we can program it without any issue:))

    We are powering nRF52832 from 3.3V and will use S0D1 for resetting.

    Thank you very much for your kindly support.

    Regards,

    Grigor

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