waking up from systemOFF resetting GPIO

[buja]

Dear Team,

i have connected a sensor to nRF52810. The sensor power suppply (VDD) is connected to one of the GPIO. My system will switch between systemON and systemOFF most of the time.

During systemOFF I can see that the sensor is working properly. I can see voltage on VDD  pin of sensor during systemOFF. But when system wakes up from systemOFF sensor is not working. 

I would like to ask that, would waking up from systemOFF reset GPIO (high --> low --> high) ? If that is the case, I will have to re-initialize the sensor each time waking up from systemOFF.. Is there any way I can retain the GPIO voltage while waking up from systemOFF ?

[Amanda Hsieh]

Hi, 

The NRF_GPIO peripheral should maintain configuration, however if you have peripheral (e.g. TWI, UART etc) controlling the pins, then during wakeup from system off it will fall back to the actual NRF_GPIO configuration. So make sure that before you go to sleep (system OFF) that you set NRF_GPIO pins to the state you want them to have when wakeup.

Also make sure you are not in debug mode during sleep, because of this errata:

[81] GPIO: PIN_CNF is not retained when in debug interface mode

-Amanda H.

[buja]

Hi Amanda,

Thank yoou for your reply.

How can we make sure the device is not in debug interface mode ? Is it by just disconnecting the debugger ?

[Amanda Hsieh]

Disconnect with the debugger. 

-Amanda H.

[buja]

Okay, Thank you