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

[Guillaume Levant]

U8 is a TPS79933 from Texas Instruments, the VIH is 1.2V. When P8 is high (at 3.3V), the EN pin voltage of the TPS79933 should be 2.2V, which is sufficient to keep it enabled. The problem is that when the button is released the device turns off, and when I measure the voltage at p8 with a multimeter I have around 20mV (with the button pressed). I tried to read the output of P8 while debugging, and it is always set to 0, despite the fact I set it to 1.