P0.08 not working with nRF51822 QFAC

[Guillaume Levant]

Hi,

I have a PCB with a nRF51822 QFAC A1 onboard, and I wrote a firmware with mbed for this PCB in which P0.08 is supposed to be set to 1 during the initialization and is never set to 0 after. But when I test the firmware this GPIO is always at 0. I tried to find a short circuit but according to my multimeter the resistance betwen p8 and Vss is 33kOhms, which is correct according to the schematic of my PCB. Is this pin has a specific function and could not be set to 1 ? I didn't find any information confirming this in the datasheet.

I use softdevice s110 7.3.0

Best regards,

Guillaume

[MartinBL]

I guess that if the TPS79933 and/or the nRF51 turn off when the button is released it is no wonder why you don't measure any significant voltage on P0.08. Maybe the voltage regulated by the TPS79933 of some reason dips just long enough for the nRF51 to power down and "release" P0.08. If that is the case then maybe a bulk capacitor can help filter out the dip and solve the problem. It is hard to tell what's wrong.