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, 1920ALDoes anyone had a similar issue?
nRESET should not be pulled up externally.
Thank you for your promptly reply.
We have tried to program the nRF9160 without pull-up resistor and there where no any result.
We can program nRF9160 only when connecting nRESET pin to 3.3V directly.
Grigor said:We can program nRF9160 only when connecting nRESET pin to 3.3V directly.
And the alternative to this, which is not working, is pulling nRESET high using a GPIO from nRF52840? What if you disconnect the GPIO in your nRF52840 code?
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 .
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)?