按键的基本原理是设置单片机IO口（PB0-PB3）为输入状态，如DDRB = 0XF0（方向寄存器，“1”为输出，“0”为输入）;

单片机一直检测按键端口（PB0-PB3）的状态，当端口为低电平时（即按键按下），实行相应的动作（比如控制LED灯）。

原理就是这么回事，但是正真实现时，按键会有抖动，要进行按键去抖，下图为按键按下时的抖动图。

按键实行一个动作过程是需要一定时间的，一般为100mS-1S左右，而一个单片机执行一个机器周期的时间很短，时钟为10MH的周期为0.1μs，这样按键每一次动作程序就会多次检测按键，出现误判（一次按下，多次动作）。

/********************************************************************************
* @file    bsp_key.c
* @author  jianqiang.xue
* @version V1.0.0
* @date    2021-04-03
* @brief   NULL
********************************************************************************/

/* Includes ------------------------------------------------------------------*/
#include <stdint.h>
#include <stdbool.h>

#include "RTE_Components.h"
#include CMSIS_device_header
#include "nrf_drv_gpiote.h"
#include "nrf_gpio.h"

#include "bsp_gpio.h"
#include "bsp_exti.h"
#include "bsp_key.h"

/* Private Includes ----------------------------------------------------------*/
#include "business_gpio.h"
#include "business_function.h"

/* Private Define ------------------------------------------------------------*/

/* Private Variables ---------------------------------------------------------*/

#if BS_BUTTON_NUM != 0
static const uint16_t g_button_pin[BS_BUTTON_NUM] = {
#if (BS_BUTTON_NUM > 0)
    BS_BUTTON0_PIN
#endif
#if (BS_BUTTON_NUM > 1)
    ,BS_BUTTON1_PIN
#endif
#if (BS_BUTTON_NUM > 2)
    ,BS_BUTTON2_PIN
#endif
#if (BS_BUTTON_NUM > 3)
    ,BS_BUTTON3_PIN
#endif
#if (BS_BUTTON_NUM > 4)
    ,BS_BUTTON4_PIN
#endif
#if (BS_BUTTON_NUM > 5)
    ,BS_BUTTON5_PIN
#endif
#if (BS_BUTTON_NUM > 6)
    ,BS_BUTTON6_PIN
#endif
#if (BS_BUTTON_NUM > 7)
    ,BS_BUTTON7_PIN
#endif
#if (BS_BUTTON_NUM > 8)
    ,BS_BUTTON8_PIN
#endif
#if (BS_BUTTON_NUM > 9)
    ,BS_BUTTON9_PIN
#endif
#if (BS_BUTTON_NUM > 10)
    ,BS_BUTTON10_PIN
#endif
};

static const bsp_gpio_pin_pull_t g_button_pull[BS_BUTTON_NUM] = {
#if (BS_BUTTON_NUM > 0)
    BS_BUTTON0_PULL
#endif
#if (BS_BUTTON_NUM > 1)
    ,BS_BUTTON1_PULL
#endif
#if (BS_BUTTON_NUM > 2)
    ,BS_BUTTON2_PULL
#endif
#if (BS_BUTTON_NUM > 3)
    ,BS_BUTTON3_PULL
#endif
#if (BS_BUTTON_NUM > 4)
    ,BS_BUTTON4_PULL
#endif
#if (BS_BUTTON_NUM > 5)
    ,BS_BUTTON5_PULL
#endif
#if (BS_BUTTON_NUM > 6)
    ,BS_BUTTON6_PULL
#endif
#if (BS_BUTTON_NUM > 7)
    ,BS_BUTTON7_PULL
#endif
#if (BS_BUTTON_NUM > 8)
    ,BS_BUTTON8_PULL
#endif
#if (BS_BUTTON_NUM > 9)
    ,BS_BUTTON9_PULL
#endif
#if (BS_BUTTON_NUM > 10)
    ,BS_BUTTON10_PULL
#endif
};

static const bool g_button_exti[BS_BUTTON_NUM] = {
#if (BS_BUTTON_NUM > 0)
    BS_BUTTON0_EXTI_SEL
#endif
#if (BS_BUTTON_NUM > 1)
    ,BS_BUTTON1_EXTI_SEL
#endif
#if (BS_BUTTON_NUM > 2)
    ,BS_BUTTON2_EXTI_SEL
#endif
#if (BS_BUTTON_NUM > 3)
    ,BS_BUTTON3_EXTI_SEL
#endif
#if (BS_BUTTON_NUM > 4)
    ,BS_BUTTON4_EXTI_SEL
#endif
#if (BS_BUTTON_NUM > 5)
    ,BS_BUTTON5_EXTI_SEL
#endif
#if (BS_BUTTON_NUM > 6)
    ,BS_BUTTON6_EXTI_SEL
#endif
#if (BS_BUTTON_NUM > 7)
    ,BS_BUTTON7_EXTI_SEL
#endif
#if (BS_BUTTON_NUM > 8)
    ,BS_BUTTON8_EXTI_SEL
#endif
#if (BS_BUTTON_NUM > 9)
    ,BS_BUTTON9_EXTI_SEL
#endif
#if (BS_BUTTON_NUM > 10)
    ,BS_BUTTON10_EXTI_SEL
#endif
};

static const bsp_gpio_exti_int_type_t g_button_irq_edge_level_sel[BS_BUTTON_NUM] = {
#if (BS_BUTTON_NUM > 0)
    BS_BUTTON0_EXTI_EDGE_LEVEL_SEL
#endif
#if (BS_BUTTON_NUM > 1)
    ,BS_BUTTON1_EXTI_EDGE_LEVEL_SEL
#endif
#if (BS_BUTTON_NUM > 2)
    ,BS_BUTTON2_EXTI_EDGE_LEVEL_SEL
#endif
#if (BS_BUTTON_NUM > 3)
    ,BS_BUTTON3_EXTI_EDGE_LEVEL_SEL
#endif
#if (BS_BUTTON_NUM > 4)
    ,BS_BUTTON4_EXTI_EDGE_LEVEL_SEL
#endif
#if (BS_BUTTON_NUM > 5)
    ,BS_BUTTON5_EXTI_EDGE_LEVEL_SEL
#endif
#if (BS_BUTTON_NUM > 6)
    ,BS_BUTTON6_EXTI_EDGE_LEVEL_SEL
#endif
#if (BS_BUTTON_NUM > 7)
    ,BS_BUTTON7_EXTI_EDGE_LEVEL_SEL
#endif
#if (BS_BUTTON_NUM > 8)
    ,BS_BUTTON8_EXTI_EDGE_LEVEL_SEL
#endif
#if (BS_BUTTON_NUM > 9)
    ,BS_BUTTON9_EXTI_EDGE_LEVEL_SEL
#endif
#if (BS_BUTTON_NUM > 10)
    ,BS_BUTTON10_EXTI_EDGE_LEVEL_SEL
#endif
};

static const bsp_gpio_exti_int_event_t g_button_irq_rise_fall_sel[BS_BUTTON_NUM] = {
#if (BS_BUTTON_NUM > 0)
    BS_BUTTON0_EXTI_RISE_FALL_SEL
#endif
#if (BS_BUTTON_NUM > 1)
    ,BS_BUTTON1_EXTI_RISE_FALL_SEL
#endif
#if (BS_BUTTON_NUM > 2)
    ,BS_BUTTON2_EXTI_RISE_FALL_SEL
#endif
#if (BS_BUTTON_NUM > 3)
    ,BS_BUTTON3_EXTI_RISE_FALL_SEL
#endif
#if (BS_BUTTON_NUM > 4)
    ,BS_BUTTON4_EXTI_RISE_FALL_SEL
#endif
#if (BS_BUTTON_NUM > 5)
    ,BS_BUTTON5_EXTI_RISE_FALL_SEL
#endif
#if (BS_BUTTON_NUM > 6)
    ,BS_BUTTON5_EXTI_RISE_FALL_SEL
#endif
#if (BS_BUTTON_NUM > 7)
    ,BS_BUTTON7_EXTI_RISE_FALL_SEL
#endif
#if (BS_BUTTON_NUM > 8)
    ,BS_BUTTON8_EXTI_RISE_FALL_SEL
#endif
#if (BS_BUTTON_NUM > 9)
    ,BS_BUTTON9_EXTI_RISE_FALL_SEL
#endif
#if (BS_BUTTON_NUM > 10)
    ,BS_BUTTON10_EXTI_RISE_FALL_SEL
#endif
};

/* External Variables --------------------------------------------------------*/
typedef void(*bsp_button_callback)(void);
static bsp_button_callback irq_callback[BS_BUTTON_NUM];
/* Private Macro -------------------------------------------------------------*/
static void bsp_button_exti_callback(void *gpiox, uint16_t gpio_pin);

/* Public Function Prototypes -----------------------------------------------*/

/**
 * @brief  [初始化] 按键引脚初始化并注册按键外部中断回调函数
 * @note   NULL
 * @retval None
 */
void bsp_button_init(void)
{
    uint8_t ch;

    for (ch = 0; ch < BS_BUTTON_NUM; ch++)
    {
        if (g_button_exti[ch] == false)
        {
            /* Configure Button pin as input */
            bsp_gpio_init_input(NULL, g_button_pin[ch], g_button_pull[ch]);
        }
        else
        {
            /* Configure Button pin as input with External interrupt */
            irq_callback[ch] = NULL;
            bsp_gpio_init_input_exit(NULL, g_button_pin[ch], NULL,
                                     g_button_irq_edge_level_sel[ch],
                                     g_button_irq_rise_fall_sel[ch],
                                     g_button_pull[ch]);
        }
    }

    if (BS_BUTTON_NUM)
    {
        bsp_gpio_exit_irq_register_callback(bsp_button_exti_callback);
    }
}

/**
 * @brief  [反初始化] 按键恢复默认状态
 * @note   NULL
 * @param  ch: 按键号
 * @retval None
 */
void bsp_button_deinit(bsp_button_t ch)
{
    bsp_gpio_deinit(NULL, g_button_pin[ch]);
}

/**
 * @brief  设置按键中断优先级(强制配置为低优先级)
 * @note   NULL
 * @param  ch: 按键号
 * @retval None
 */
void bsp_button_set_irq(bsp_button_t ch)
{
    bsp_exit_set(g_button_pin[ch], 0);
}

/**
 * @brief  清除按键中断优先级
 * @note   NULL
 * @param  ch: 按键号
 * @retval None
 */
void bsp_button_clear_irq(bsp_button_t ch)
{
    bsp_exit_clear_set(g_button_pin[ch]);
}

/**
 * @brief  得到按键状态
 * @note   NULL
 * @param  ch: 按键号
 * @retval 0 -- 低电平, 1 -- 高电平
 */
bool bsp_button_get_state(bsp_button_t ch)
{
    return bsp_gpio_get_state(NULL, g_button_pin[ch]);
}

/**
 * @brief  注册按键中断的回调函数
 * @note   NULL
 * @param  ch: 键号
 * @param  event: 绑定中断回调事件
 * @retval 0--失败  1--成功
 */
bool bsp_button_irq_callback(bsp_button_t ch, void *event)
{
    if (irq_callback[ch] != NULL)
    {
        return false;
    }
    else
    {
        irq_callback[ch] = (bsp_button_callback)event;
    }
    return true;
}

/**
 * @brief  用于外部中断服务回调，并执行对应引脚的事件
 * @note   NULL
 * @param  gpiox: -
 * @param  gpio_pin: 引脚号
 * @retval None
 */
static void bsp_button_exti_callback(void *gpiox, uint16_t gpio_pin)
{
#if BS_BUTTON_NUM > 0
    if (gpio_pin == BS_BUTTON0_PIN && irq_callback[BSP_BUTTON_X_0] != NULL)
    {
        if (irq_callback[BSP_BUTTON_X_0])
        {
            irq_callback[BSP_BUTTON_X_0]();
        }
    }
#endif
#if BS_BUTTON_NUM > 1
    else if (gpio_pin == BS_BUTTON1_PIN && irq_callback[BSP_BUTTON_X_1] != NULL)
    {
        if (irq_callback[BSP_BUTTON_X_1])
        {
            irq_callback[BSP_BUTTON_X_1]();
        }
    }
#endif
#if BS_BUTTON_NUM > 2
    else if (gpio_pin == BS_BUTTON2_PIN && irq_callback[BSP_BUTTON_X_2] != NULL)
    {
        if (irq_callback[BSP_BUTTON_X_2])
        {
            irq_callback[BSP_BUTTON_X_2]();
        }
    }
#endif
#if BS_BUTTON_NUM > 3
    else if (gpio_pin == BS_BUTTON3_PIN && irq_callback[BSP_BUTTON_X_3] != NULL)
    {
        if (irq_callback[BSP_BUTTON_X_3])
        {
            irq_callback[BSP_BUTTON_X_3]();
        }
    }
#endif
#if BS_BUTTON_NUM > 4
    else if (gpio_pin == BS_BUTTON4_PIN && irq_callback[BSP_BUTTON_X_4] != NULL)
    {
        if (irq_callback[BSP_BUTTON_X_4])
        {
            irq_callback[BSP_BUTTON_X_4]();
        }
    }
#endif
#if BS_BUTTON_NUM > 5
    else if (gpio_pin == BS_BUTTON5_PIN && irq_callback[BSP_BUTTON_X_5] != NULL)
    {
        if (irq_callback[BSP_BUTTON_X_5])
        {
            irq_callback[BSP_BUTTON_X_5]();
        }
    }
#endif
#if BS_BUTTON_NUM > 6
    else if (gpio_pin == BS_BUTTON6_PIN && irq_callback[BSP_BUTTON_X_6] != NULL)
    {
        if (irq_callback[BSP_BUTTON_X_6])
        {
            irq_callback[BSP_BUTTON_X_6]();
        }
    }
#endif
#if BS_BUTTON_NUM > 7
    else if (gpio_pin == BS_BUTTON7_PIN && irq_callback[BSP_BUTTON_X_7] != NULL)
    {
        if (irq_callback[BSP_BUTTON_X_7])
        {
            irq_callback[BSP_BUTTON_X_7]();
        }
    }
#endif
#if BS_BUTTON_NUM > 8
    else if (gpio_pin == BS_BUTTON8_PIN && irq_callback[BSP_BUTTON_X_8] != NULL)
    {
        if (irq_callback[BSP_BUTTON_X_8])
        {
            irq_callback[BSP_BUTTON_X_8]();
        }
    }
#endif
#if BS_BUTTON_NUM > 9
    else if (gpio_pin == BS_BUTTON9_PIN && irq_callback[BSP_BUTTON_X_9] != NULL)
    {
        if (irq_callback[BSP_BUTTON_X_9])
        {
            irq_callback[BSP_BUTTON_X_9]();
        }
    }
#endif
#if BS_BUTTON_NUM > 10
    else if (gpio_pin == BS_BUTTON10_PIN && irq_callback[BSP_BUTTON_X_10] != NULL)
    {
        if (irq_callback[BSP_BUTTON_X_10])
        {
            irq_callback[BSP_BUTTON_X_10]();
        }
    }
#endif
}

#else
void bsp_button_init(void)
{
}

void bsp_button_deinit(bsp_button_t ch)
{
}

bool bsp_button_get_state(bsp_button_t ch)
{
    return false;
}

bool bsp_button_irq_callback(bsp_button_t ch, void *event)
{
    return false;
}

void bsp_button_exti_callback(void *gpiox, uint16_t gpio_pin)
{
}
#endif

/********************************************************************************
* @file    bsp_key.h
* @author  jianqiang.xue
* @version V1.0.0
* @date    2021-04-03
* @brief   bsp key
********************************************************************************/

#ifndef __BSP_KEY_H
#define __BSP_KEY_H

/* Includes ------------------------------------------------------------------*/
#include <stdint.h>
#include <stdbool.h>

/* Public enum ---------------------------------------------------------------*/
typedef enum
{
    BSP_BUTTON_X_0 = 0,
    BSP_BUTTON_X_1,
    BSP_BUTTON_X_2,
    BSP_BUTTON_X_3,
    BSP_BUTTON_X_4,
    BSP_BUTTON_X_5,
    BSP_BUTTON_X_6,
    BSP_BUTTON_X_7,
    BSP_BUTTON_X_8,
    BSP_BUTTON_X_9,
    BSP_BUTTON_X_10
} bsp_button_t;

typedef enum
{
    BUTTON_MODE_GPIO = 0,
    BUTTON_MODE_EXTI = 1
} bsp_button_mode_t;

/* Public Function Prototypes ------------------------------------------------*/

void bsp_button_init(void);
void bsp_button_deinit(bsp_button_t ch);

void bsp_button_set_irq(bsp_button_t ch);
void bsp_button_clear_irq(bsp_button_t ch);

bool bsp_button_get_state(bsp_button_t ch);

bool bsp_button_irq_callback(bsp_button_t ch, void *event);

#endif