NCS: How to configure gpio input pins?

RE: NCS: How to configure gpio input pins?

Øivind — Wed, 01 Dec 2021 16:46:44 GMT

In your code, could you try to replicate how it is done in zephyr/samples/basic/button?

static const struct gpio_dt_spec button = GPIO_DT_SPEC_GET_OR(DT_NODELABEL(buttonred), gpios,
							      {0});
							      
gpio_pin_configure_dt(&button, GPIO_INPUT | GPIO_INT_DEBOUNCE);

gpio_pin_interrupt_configure_dt(&button, GPIO_INT_EDGE_BOTH);
					      
gpio_init_callback(&gpio_button_callback, button_callback, BIT(button.pin));

gpio_add_callback(button.port, &gpio_button_callback);

gpio_pin_get_dt(&button);

RE: NCS: How to configure gpio input pins?

BlueMike — Wed, 01 Dec 2021 16:11:14 GMT

So the device tree overlay now looks like this:

/ {
    buttons {
        compatible = "gpio-keys";
        buttonred: button_red {
            gpios = <&gpio0 0x5 0x11>;
            label = "Button red.";
        };
    };
};

&uart0 {
    /delete-property/rts-pin;
    /delete-property/status;
};

Please note:

gpio pin 5 has been unassigned as uart0 rts-pin.
a new button has been added for pin 5 instead.

Still the same behavior: Calling gpio_pin_get(5) at the isr crashes the firmware...

Any ideas why it crashes and how to fix it are welcome.

Thank you,
Michael.

RE: NCS: How to configure gpio input pins?

Øivind — Wed, 01 Dec 2021 13:17:13 GMT

Ah, I'm sorry, I was mixing up a bit with another api. You need the pin in the device tree. You can add it to the overlay, like how buttons are added in the board files.

RE: NCS: How to configure gpio input pins?

BlueMike — Wed, 01 Dec 2021 12:06:04 GMT

gpio_pin_configure(), gpio_add_callback() and gpio_pin_interrupt_configure() all return zero. The interrupt happens and the callback is executed, however, calling gpio_pin_get(5) from inside the callback crashes the application.

Maybe I should just handle the interrupt in a thread outside the isr, would be no effort, however, I'm having a bad feeling workarounding a crash without knowing the reason for the crash....

RE: NCS: How to configure gpio input pins?

Øivind — Wed, 01 Dec 2021 11:07:37 GMT

gpio_pin_configure(), gpio_add_callback() and gpio_pin_interrupt_configure() all return 0 if they are successful, and a negative error code on failure. Could you check if any of them return error codes?

RE: NCS: How to configure gpio input pins?

BlueMike — Tue, 30 Nov 2021 20:56:36 GMT

Hi Øivind,

Thanks for your help!

Outside the isr, gpio_pin_get(3) returns 0 - thanks for pointing in that direction! Would be nice to have it return zero from inside the isr as well, but that's easy to workaround.

Yes, I'm building for nrf52dk_nrf52832 with the default board files. I've first tried to remove rts-pin by adding the following to the overlay:

&uart0 {
    /delete-property/rts-pin;
};

This successfully removes rts-pin from uart0, however the app still crashes when calling gpio_pin_get(5). So I've tried to remove the complete uart0:

/ {   
   chosen {
        /delete-property/zephyr,console;
        /delete-property/zephyr,shell-uart;
        /delete-property/zephyr,uart-mcumgr;
        /delete-property/zephyr,bt-mon-uart;
        /delete-property/zephyr,bt-c2h-uart;
    };
    /delete-node/arduino_serial; 
    /delete-node/uart0;
};

Unfortunately this didn't work: uart0 is still in the device tree, and calling gpio_pin_get(5) still crashes. Do you have any other ideas how to fix the crash?

RE: NCS: How to configure gpio input pins?

Øivind — Tue, 30 Nov 2021 19:12:03 GMT

Hi,

It would be useful to have a little more information about your application.

Are you able to get 0 from gpio_pin_get() at other times, for example if you call it outside of the callback?

Are you building for nrf52dk_nrf52832 with the default board files? By default pin 5 is set as the RTS pin for uart0.