Zephyr Save GPIO output status after reset

[LucaMar]

Hi All,

I am using a nrf52840 chip with Zephyr OS. I wanted to know if there is a way to save the status of a GPIO output pin after a reset (caused by the Watchdog timer).

I found the initialization GPIO API:

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int gpio_pin_configure_dt(const struct gpio_dt_spec *spec, gpio_flags_t extra_flags)

And passing as flag:  “GPIO_OUTPUT" in the documentation it is written "/** Enables pin as output, no change to the output state. */", so I thought that maybe it could save the GPIO output status. 

As soon as the device resets I am experiencing the GPIO pin changing it's status, I thought that maybe the WDT resets the entire SOC (GPIO peripheral included).

Am I doing something wrong? Is there a better way to do it?

Thanks.

[LucaMar]

I missed to say that before resetting I put the GPIO status to one of the two logic status, example of operations:

1. Init GPIO with gpio_pin_configure_dt and "GPIO_OUTPUT" flag;

2. force GPIO status to "1"

3. reset by watchdog (or button reset)

4. The GPIO status changed it's value to "0"

[Vidar Berg]

Hi,

It is not possible to retain the GPIO configurations through a WD reset. The reset will reconfigure all pins to their default state.

Reset behavior

Default reset state:

PIN_CNF[n]

I may be able to suggest another approach if you could provide a bit more information about the use case and what you are trying to achieve.

Best regards,

Vidar

[LucaMar]

I wanted to retain the GPIO output status after a reset occurs so that after reset it will recover it's status, and I thought a solution "confined" to the GPIO peripheral without involving any non-volatile memory. But at this point I don't know if it is possible

[Vidar Berg]

Yes, that will require use of NV memory, or GPREGRET.

[LucaMar]

ok for NV memory, but for GPREGRET I am seeing that a WD reset will clear and reset the value, does it?