Not able to set P.021 to 0 V

RE: Not able to set P.021 to 0 V

Kenneth — Wed, 14 Aug 2019 14:18:59 GMT

Seems they have added a pull up and capacitor on the pin, likely to make it more "robust" as a reset pin. I suggest to use a different pin.

Best regards,
Kenneth

RE: Not able to set P.021 to 0 V

antoniov — Wed, 14 Aug 2019 13:52:09 GMT

Hi Kenneth,

I just followed your suggestion. With the pin not configured, I read 2.86 V at the output and I get 286 uA when I measure the current from P.021 to GND, meaning R= 10k.

I have also opened the module and I found this:

Do you think there is a workaround to solve the problem or I am obliged to choose another pin to get 0V ?

RE: Not able to set P.021 to 0 V

antoniov — Wed, 14 Aug 2019 13:29:29 GMT

Do you mean leaving the pin unconfigured in my firmware and take the measurement?

RE: Not able to set P.021 to 0 V

Kenneth — Wed, 14 Aug 2019 13:24:58 GMT

If you don't configure the pin, have you tried to connect a multimeter to P0.21 and measure the current (if any) from P0.21 to VDD and P0.21 to GND. Then you should get good indication if there is any pull active on the pin by ohms law (R = VDD / I).

Best regards,
Kenneth

RE: Not able to set P.021 to 0 V

antoniov — Wed, 14 Aug 2019 13:04:59 GMT

Hi Kenneth,

I am aware of that, and I have removed CONFIG_GPIO_AS_PINRESET from the preprocessor (I am using Seggerer Embedded Studio), but I still get 38 mV.

I will try to open the module to check inside.

RE: Not able to set P.021 to 0 V

Kenneth — Wed, 14 Aug 2019 12:54:32 GMT

It's worth mentioning that the P0.21 may be configured to be used as a pin reset:

https://infocenter.nordicsemi.com/topic/ps_nrf52810/pin.html?cp=3_3_0_6_0

So make sure there is no specific pull on the pin on the module and/or that you have defined CONFIG_GPIO_AS_PINRESET which will enable pin reset in system_nrf52810.c