Button Press detected twice when pushed once

[Moritz_S]

Hi,

I'm using a custom board to record i2s data to a sd card. The recording starts and stops on a button press (Pin 25), which basically works. My problem is that the button press is always detected twice (once on pushing the button, once on release). The button is pulled to high by hardware, so I'm sensing when there is a transition to low. I'm using the app button handler library, nRF5 SDK 17.1.0 and Segger emStudio 5.42a.

Here are the related functions.

main()

int main(void) {
    uint32_t err_code;
    uint8_t sample_data;
    uint8_t response;
    bool detected_device = false;

    log_init();

    init_clock();

    bsp_board_init(BSP_INIT_LEDS);
    bsp_board_led_on(BSP_BOARD_LED_0);

    // init buttons
    timers_init();
    buttons_init();
    
    ...
}

init_clock()

void init_clock()
{
    NRF_CLOCK->LFCLKSRC            = (CLOCK_LFCLKSRC_SRC_Xtal << CLOCK_LFCLKSRC_SRC_Pos);
    NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;
    NRF_CLOCK->TASKS_LFCLKSTART    = 1;
    while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0); // Wait for clock to start
}

buttons_init()

static void buttons_init(void)
{
    ret_code_t err_code;

    //The array must be static because a pointer to it will be saved in the button handler module.
    static app_button_cfg_t buttons[] =
    {
        {25, false, NRF_GPIO_PIN_PULLUP, button_event_handler}
    };

    err_code = app_button_init(buttons, ARRAY_SIZE(buttons),
                               BUTTON_DETECTION_DELAY);
    APP_ERROR_CHECK(err_code);

    err_code = app_button_enable();
    APP_ERROR_CHECK(err_code);

    NRF_LOG_INFO("Button enabled");
}

I also changed the configuration in app_button.c in app_button_init(), which was

nrf_drv_gpiote_in_config_t config = GPIOTE_CONFIG_IN_SENSE_TOGGLE(false);

and I changed it to:

nrf_drv_gpiote_in_config_t config = GPIOTE_CONFIG_IN_SENSE_HITOLO(false);

Is there an error in my configuration or do you think this is a hardware issue?

I appreciate any help, thanks!

[Simonr]

Hi

It sounds like you're not having a debounce implemented in your application. The button handler lib uses the GPIOTE handler to detect a button that has been pushed, and should start a timer in the GPIOTE event handler to handle this. The button will only be reported as pushed if the corresponding pin is still active when the timer expires. If there is a new GPIOTE event while the timer is running, the timer is restarted.

For the hardware side of things, as long as there is a pull-up on the pin (internal or external) and there is a physical switch or button that connect the input to ground when pressed, then it can be used as a button. Are you using a Development Kit or a custom board for your application?

Best regards,

Simon

[Moritz_S]

Hi Simonr,

I'm including the "app_button.h" header, I initialize the clock (see init_clock above) and the buttons (see buttons_init above) as it is shown in the ble_blinky example. If this is done correctly, I don't see why the timer should not work (app_timer.h is also included an initialized in timers_init()).

We are using a custom board. I will verify with my hardware expert, if the button is installed correctly. Does the app_timer library rely on an external crystal or is everything built into the SOC (we are using nrf52832).

[Simonr]

Hi

The app_timer library does indeed use the configured LF clock/crystal by default. In our example projects the default configuration is to use the optional external 32.768 kHz crystal. If you don't have this crystal on your custom board you will have to use the internal RC oscillator instead. In your timer_init() function it seems like you are using the external LF crystal though.

Best regards,

Simon

[Moritz_S]

Hi Simon,

thanks for your answer. I just wanted to let you know that we are still looking into this. I will get back to you after my holidays.

Kind regards,

Moritz