Use sys_poweroff() when GPIOs remain powered

[MTB]

Hello,

I have a question regarding the sys_poweroff() function. In my device, there is a mode where the board (including the nRF52840 chip and GPIOs) remains powered, but the chip itself is turned off using sys_poweroff().

I came across a thread on the Nordic DevZone discussing the default state of the nRF52840's GPIOs (NRF52840 GPIO default state - Nordic Q&A - Nordic DevZone - Nordic DevZone). It mentions that GPIOs should not be powered if the chip is unpowered. My concern is whether this requirement applies to the state induced by sys_poweroff(), or if it only pertains to situations where the chip is physically disconnected from its power supply.

Could you please help clarify this?

Thanks in advance!

[Turbo J]

Look at the absolute maximum ratings:  There is a diode between the (GP)IOs and the VDD rail - so only the 0.3V diode drop is allowed.

This is external power into the chip and does not apply to internally deactivated stuff during system_off as long as all VDD pins keep getting voltage.

[Jørgen Holmefjord]

Hi,

The GPIO configuration is retained during SystemOFF mode. Even after the reset caused by a wakeup from SystemOFF, the GPIO config will be retained (see Reset behavior).

Best regards,
Jørgen