NRF51822之app_button使用

我们现在开始使用app_button，为什么要使用这个来替代直接使用GPIOTE呢？

因为我们在手册中可以看到如果一直开启GPIOTE in模式的需要需要很大电流。所以我们需要使用RTC来“周期”的查询。

/** @file
* @brief Example app_button project.
*
*/
#include <stdbool.h>
#include <string.h>
#include "app_button.h"
#include "boards.h"
#include "app_gpiote.h"
#include "app_timer.h"

#define APP_TIMER_PRESCALER                  0                                          /**< Value of the RTC1 PRESCALER register. */
#define APP_TIMER_OP_QUEUE_SIZE              4                                          /**< Size of timer operation queues. */

#define BUTTON_DEBOUNCE_DELAY                50 // Delay from a GPIOTE event until a button is reported as pushed.
#define APP_GPIOTE_MAX_USERS                 1  // Maximum number of users of the GPIOTE handler. 

/*
 * Handler to be called when button is pushed.
 * param[in]   pin_no             The pin number where the event is genereated
 * param[in]   button_action     Is the button pushed or released
 */
static void button_handler(uint8_t pin_no, uint8_t button_action)
{
    if(button_action == APP_BUTTON_PUSH)
    {
        switch(pin_no)
        {
            case BUTTON_1:
                nrf_gpio_pin_toggle(LED_1);
                break;
            case BUTTON_2:
                nrf_gpio_pin_toggle(LED_2);
                break;
            case BUTTON_3:
                nrf_gpio_pin_toggle(LED_3);
                break;
            case BUTTON_4:
                nrf_gpio_pin_toggle(LED_4);
                break;
            default:
                break;
        }
    }
　　//if(button_action == APP_BUTTON_RELEASE)//键释
}

/**
 * Initialize the clock.
 */
void init_clock()
{
    NRF_CLOCK->LFCLKSRC            = (CLOCK_LFCLKSRC_SRC_Xtal << CLOCK_LFCLKSRC_SRC_Pos);
    NRF_CLOCK->EVENTS_LFCLKSTARTED = ;
    NRF_CLOCK->TASKS_LFCLKSTART    = ;
    ); // Wait for clock to start
}    

/**
 * Initialize all four LEDs on the nRF51 DK.
 */
void init_leds()
{
    nrf_gpio_cfg_output(LED_1);
    nrf_gpio_cfg_output(LED_2);
    nrf_gpio_cfg_output(LED_3);
    nrf_gpio_cfg_output(LED_4);
    nrf_gpio_pin_set(LED_1);
    nrf_gpio_pin_set(LED_2);
    nrf_gpio_pin_set(LED_3);
    nrf_gpio_pin_set(LED_4);
}    

/**@brief Function for the Power Management.
 */
static void power_manage(void)
{
    // Use directly __WFE and __SEV macros since the SoftDevice is not available.

    // Wait for event.
    __WFE();

    // Clear Event Register.
    __SEV();
    __WFE();
}

/**
 * Function for application main entry.
 */
int main(void)
{
    init_leds();
    init_clock();

    uint32_t err_code;

    // Button configuration structure.
    static app_button_cfg_t p_button[] = {  {BUTTON_1, APP_BUTTON_ACTIVE_LOW, NRF_GPIO_PIN_PULLUP, button_handler},
                                            {BUTTON_2, APP_BUTTON_ACTIVE_LOW, NRF_GPIO_PIN_PULLUP, button_handler},
                                            {BUTTON_3, APP_BUTTON_ACTIVE_LOW, NRF_GPIO_PIN_PULLUP, button_handler},
                                            {BUTTON_4, APP_BUTTON_ACTIVE_LOW, NRF_GPIO_PIN_PULLUP, button_handler}};

    // Macro for initializing the application timer module.
    // It will handle dimensioning and allocation of the memory buffer required by the timer, making sure that the buffer is correctly aligned. It will also connect the timer module to the scheduler (if specified).
    APP_TIMER_INIT(APP_TIMER_PRESCALER, APP_TIMER_MAX_TIMERS, APP_TIMER_OP_QUEUE_SIZE, NULL);

    // Macro for initializing the GPIOTE module.
    // It will handle dimensioning and allocation of the memory buffer required by the module, making sure that the buffer is correctly aligned.
    APP_GPIOTE_INIT(APP_GPIOTE_MAX_USERS);

    // Initializing the buttons.
    err_code = app_button_init(p_button, ]), BUTTON_DEBOUNCE_DELAY);
    APP_ERROR_CHECK(err_code);

    // Enabling the buttons.
    err_code = app_button_enable();
    APP_ERROR_CHECK(err_code);

    while(true)
    {
       power_manage();
    }
}

需要注意的是app_button底层调用app_time和app_gpiote。而在裸机下需要我们配置好32khz时钟，即在代码中init_clock。