nRESET pin internal pull-up disable (P0.18)

[krisburch]

Hello,

In our current design, our boards use P0.18 connected to an external watchdog to reset the nRF52840. We configure PSETRESET[0]/[1] to be 0x12 (Connected/enabled on P0.18), and we see the reset functionality works. 

However, we see there is a strong internal pullup on this P0.18 pin that gets enabled when using this functionality. We have external circuitry to handle this line pull, and would like to disable the pullup. We checked the GPIO config (0x50000748 for P0.18), and see there is no pullup applied on the GPIO configs that we can disable after enabling PSETRESET. Is there any way to disable this pullup with any other method? 

Thank you

[Robin M Saltnes]

Hello krisburch, 

The internal pullup resistors for reset pins are implemented as a hardwired part of the chip on nRF SoCs. Because of this there is no way of disabling them in software while the pin is configured as a reset. 

Best regards 

Robin  

[krisburch]

Thanks Robin