Debounce in callbacks

RE: Debounce in callbacks

mike_actinius — Fri, 04 Feb 2022 01:13:14 GMT

Hello Baowz,

A device tree declaration will not initialize a pull-up resistor, you have to do it in the gpio_pin_configure(). If you want to use a similar way with what we do in the "leds & button" sample, then you should declare an extra button in your overlay (you can copy paste the button declaration from the icarus board files and change the gpio to pin 0 where you seem to have your external button connected) and just initialize the gpio the same way it is done for the on-board button in the sample, i.e. using the device tree flags in gpio_pin_configure().

BR,

Mike

RE: Debounce in callbacks

Baowz — Tue, 01 Feb 2022 14:31:53 GMT

Hello again, Mike!

The code works perfectly, thank you so much for the help!

Just a quick question when it comes to enabling the resistor in the GPIO. Should I do it the same way as I did with the button? I used the sample that is shown from your website found here. And the way I tried to initialize the resistor is as follows:

...   
    resistors {
        TV_resistor: resistor0 {
            gpios = <&gpio0 0 GPIO_PULL_UP>;
            label = "Video resistor";
        };
    };
	aliases {
	   ...
	   resistor0 = &TV_resistor;
    };
...

RE: Debounce in callbacks

mike_actinius — Mon, 31 Jan 2022 22:29:36 GMT

Hi Baowz,

You should declare the `last_button_press_time` variable outside the function, I edited my answer above to show you how the `last_button_press_time` and `BUTTON_DEBOUNCE_TIME` can be declared.

The `newPressTime` is just used so that the "entry" time is used as a last_button_press_time, you can even skip it, and put the uptime directly in the `last_button_press_time` if you prefer.

BR,

Mike

RE: Debounce in callbacks

Baowz — Mon, 31 Jan 2022 14:31:12 GMT

This seems to be a really good solution, thank you! However, I'm a little bit confused by the code. You say that you want to store it in a variable called "last_button_press_time". But it ends up being stored in "newPressTime" and "last_button_press_time" is never declared. I feel like I'm missing something from your explanation, I'm sorry about that. But can you elaborate a little bit more for me?

RE: Debounce in callbacks

mike_actinius — Fri, 28 Jan 2022 23:52:32 GMT

Hi Baowz,

For debouncing a button, you can simply keep the uptime value at the moment of the button callback (eg k_uptime_get_32()) in a variable, let's call it last_button_press_time, and in your callback do something like the following:

#define BUTTON_DEBOUNCE_TIME 50
uint32_t last_button_press_time;

void button_pressed_callback(...) {
    uint32_t newPressTime = k_uptime_get_32();

    // debounce
    if (k_uptime_get_32() - last_button_press_time < BUTTON_DEBOUNCE_TIME) {
        return;
    }

    is_button_press_pending = true;
    // use (and re-set) the `is_button_press_pending` flag in your main loop
    // or submit work to queue at this point

    last_button_press_time = newPressTime;
}

Also, it sounds like you may not have the internal pull-up resistor active on your input, making your pin floating and triggering "too easily". Make sure to turn it on when you initialize your GPIO.

Let me know in case of any questions!

BR,

Mike

RE: Debounce in callbacks

Charlie — Thu, 20 Jan 2022 11:37:41 GMT

Hi Christian,

Debounce need dealy, it is not wise to introduce significant dealy on a call back in the interrupt handler.

Maybe you can also think about a hardware solution?

I am not sure if you have seen similar complaints on the board you are using. Do you have any chance to play with the Nordic nRF DK board? The combination of the HW+FW solution could be a good reference for your development.

Best regards,

Charlie

RE: Debounce in callbacks

Baowz — Wed, 19 Jan 2022 14:28:44 GMT

Hello again, Charlie!

Before I made this post I was looking around for some suitable debounce code. However, I found none that was implemented directly into the callback, hence this post. Is there a reason why I can't find any that suits my use?

RE: Debounce in callbacks

Charlie — Tue, 18 Jan 2022 13:26:39 GMT

Hi Christian,

This sample does not support actinius Icarus board and it also has big differences with our supported nRF DK boards, so it will take some effort to modify the sample to fit this board.

I suggest you either switch to nRF9160DK to continue the learning of CAF or just search "debounce code in c" to quickly catch some debouncing implementation for your application. The general theory is that on edge detection wait for several ms and detect edge again and if the change is still present then it is a true change. The button.c from CAF set debounce interval CAF_BUTTONS_DEBOUNCE_INTERVAL 2ms as default.

Best regards,

Charlie

RE: Debounce in callbacks

Baowz — Tue, 18 Jan 2022 12:37:02 GMT

I do not recall making any changes except for changing the pin numbers that fits the board. Have you tried to compile the code for actinius_Icarus_ns? Since that's the board I'm using and not the nrf9160dk. Not sure if that makes any difference?

RE: Debounce in callbacks

Charlie — Tue, 18 Jan 2022 10:16:09 GMT

Hi Christian,

I did not encounter this error after adding these files for the nrf9160dk_nrf9160_ns building with the original Common Application Framework preview sample.

Did you make any changes?

Best regards,

Charlie

RE: Debounce in callbacks

Baowz — Mon, 17 Jan 2022 14:26:03 GMT

Hello again!

Thank you for the response.

I'm currently using the Icarus IoT dev board with the nRF9160 chip. I have already implemented the buttons.c, buttons_def.h, and the overlay. I'm curious if the led_state_def.h is necessary? I have not implemented it and is that why I get the error in the "module_set_state" function? This function is declared in the "module_state_event.h" file.

RE: Debounce in callbacks

Charlie — Mon, 17 Jan 2022 12:53:06 GMT

Hi Christian,

You need to add the following configuration files to add support for nrf9160dk_nrf9160_ns building:

boards\nrf9160dk_nrf9160_ns.overlay

configuration\nrf9160dk_nrf9160_ns\led_state_def.h

configuration\nrf9160dk_nrf9160_ns\buttons_def.h

You can copy these files from nrf5340dk_nrf5340_cpuapp and refer to the nRF9160DK Buttons, slide switches, and LEDs pins assignment to modify them.

Best regards,

Charlie

RE: Debounce in callbacks

Baowz — Fri, 14 Jan 2022 17:27:19 GMT

It does not seem like the sample works for nRF9160 I keep getting an error in the " module_set_state" function.

undefined reference to '__event_type_module_state_event'

So it seems I have to make one from scratch then?

RE: Debounce in callbacks

Charlie — Fri, 14 Jan 2022 12:58:39 GMT

Hi Christian,

The sample may be not written and tested with nRF9160DK board, but I am pretty sure CAF can be used by nRF9160 SiP.

Best regards,

Charlie

RE: Debounce in callbacks

Baowz — Fri, 14 Jan 2022 11:47:35 GMT

Hello, Charlie! thank you for your reply.

I see in the CAF sample you sent me, in the "requirements" it only supports nRF52840 and nRF5340. The board that I have is using nRF9160, do you think it will work anyway?

RE: Debounce in callbacks

Charlie — Fri, 14 Jan 2022 10:25:02 GMT

Hi Christian,

Thanks for checking with us. Our Common Application Framework Buttons module actually has button debounce support, you can find the implementation from nrf\subsys\caf\modules\buttons.c file.

For your development, you can either implement your own debounce function by referring to the buttons.c source codes or just learn how to use CAF. Common Application Framework preview sample could be a good start point.

Best regards,

Charlie