Read current value of an OUTPUT gpio pin

RE: Read current value of an OUTPUT gpio pin

Achim Kraus — Wed, 12 Nov 2025 17:24:42 GMT

[quote userid="125646" url="~/f/nordic-q-a/104417/read-current-value-of-an-output-gpio-pin/449528"] you can use still use Zephyr's gpio_pin_get() to get the state of the the output pin.[/quote]

To be more precise: you read to level of the input at that pin. If the output is high, but the load pulls it too much down, you will read a low instead of the value high set to the output. Maybe in my case, the load is out of spec.

RE: Read current value of an OUTPUT gpio pin

Pedro — Tue, 10 Oct 2023 11:51:10 GMT

Thank you Joe! This also works.

Anyway, I'm curious about knowing how to know the include path for any .h file, which does not corresponds with the system folder structure. Somebody knows?

Regards,

Pedro.

RE: Read current value of an OUTPUT gpio pin

Joe Kane — Tue, 10 Oct 2023 11:01:38 GMT

Pedro,

Actually, you can use still use Zephyr's gpio_pin_get() to get the state of the the output pin.

The trick is to configure the pin as both an output and input in Zephyr, like this:

gpio_pin_configure_dt(&led1, GPIO_OUTPUT_INACTIVE | GPIO_INPUT);

and now gpio_pin_get() will work.

RE: Read current value of an OUTPUT gpio pin

Pedro — Tue, 10 Oct 2023 10:31:30 GMT

Thanks Einar!

How can I find in the future the include path for other .h files? They do not correspond with the system folder structure.

RE: Read current value of an OUTPUT gpio pin

Einar Thorsrud — Tue, 10 Oct 2023 10:27:06 GMT

Hi Pedro,

You should include it like this:

#include <hal/nrf_gpio.h>

RE: Read current value of an OUTPUT gpio pin

Pedro — Tue, 10 Oct 2023 09:52:02 GMT

Ah, I see.

I've found this function in C:\ncs\v2.0.2\modules\hal\nordic\nrfx\hal\nrf_gpio.h

But, how can I include it in my project?

If I try #include <modules/hal/nordic/nrfx/hal/nrf_gpio.h> it does not find the file.

I do not understand the include paths when using NCS. They do not correspond exactly with file system folder structure.

Thanks again!

Pedro.

RE: Read current value of an OUTPUT gpio pin

Einar Thorsrud — Tue, 10 Oct 2023 07:58:08 GMT

It is a low-level function from nrfx that is available regardless of which SDK you are using. It exist in NCS v2.0.2, and also in the latest v2.4.2.

RE: Read current value of an OUTPUT gpio pin

Pedro — Tue, 10 Oct 2023 07:06:54 GMT

But, how can I use nrf_gpio_pin_out_read() with NCS v2.0.2, with Zephyr? Isn't it a function of the old Nordic SDK?

RE: Read current value of an OUTPUT gpio pin

Einar Thorsrud — Tue, 10 Oct 2023 07:04:45 GMT

Hi Pedro,

You are right, gpio_pin_get() can only be used to read an input pin. That is why I suggested that you use nrf_gpio_pin_out_read() , which is for reading the state of an output pin 🙂

RE: Read current value of an OUTPUT gpio pin

Pedro — Mon, 09 Oct 2023 07:23:56 GMT

Hi Einar,

I'm using NCS v2.0.2, with Zephyr, so I use gpio_pin_get(). The problem is when GPIO is configured as output, I can not use this function to read its current value.

How can I do this?

Thanks and kind regards,

Pedro.

RE: Read current value of an OUTPUT gpio pin

Einar Thorsrud — Fri, 06 Oct 2023 11:23:35 GMT

Hi,

You can use nrf_gpio_pin_out_read() to read the state of an output pin in the OUT register.