nrf52840用keil5实现按下按键1、2、3、4，LED灯1、2、3、4分别以500ms、1s、2s、3s的时间做流水灯操作（使用定时器控制时间）

以下是nrf52840用keil5实现按下按键1、2、3、4，LED灯1、2、3、4分别以500ms、1s、2s、3s的时间做流水灯操作的代码实现：

#include "nrf.h"
#include "nrf_gpio.h"
#include "nrf_delay.h"
#include "nrfx_timer.h"

#define LED1 17
#define LED2 18
#define LED3 19
#define LED4 20

#define BUTTON1 13
#define BUTTON2 14
#define BUTTON3 15
#define BUTTON4 16

nrfx_timer_t My_Timer0 = NRFX_TIMER_INSTANCE(0);

void My_Timer0_Interrupt(nrf_timer_event_t event_type, void * p_context) //1ms
{
    static uint16_t flag_500ms, flag_1s, flag_2s, flag_3s;
    switch (event_type)
    {
        case NRF_TIMER_EVENT_COMPARE0: // 匹配到了1ms的次数了
            if (++flag_500ms == 500) //500ms
            {
                nrf_gpio_pin_toggle(LED1);
                flag_500ms = 0;
            }
            if (++flag_1s == 1000) //1s
            {
                nrf_gpio_pin_toggle(LED2);
                flag_1s = 0;
            }
            if (++flag_2s == 2000) //2s
            {
                nrf_gpio_pin_toggle(LED3);
                flag_2s = 0;
            }
            if (++flag_3s == 3000) //3s
            {
                nrf_gpio_pin_toggle(LED4);
                flag_3s = 0;
            }
            break;
        default:
            //Do nothing.
            break;
    }
}

int main(void)
{
    nrf_gpio_cfg_output(LED1);
    nrf_gpio_cfg_output(LED2);
    nrf_gpio_cfg_output(LED3);
    nrf_gpio_cfg_output(LED4);

    nrfx_timer_config_t timer_cfg = NRFX_TIMER_DEFAULT_CONFIG;
    nrfx_timer_init(&My_Timer0, &timer_cfg, My_Timer0_Interrupt);
    uint32_t time_ticks;
    time_ticks = nrfx_timer_ms_to_ticks(&My_Timer0, 1); //算出1ms需要计数多少次
    nrfx_timer_extended_compare(&My_Timer0, NRF_TIMER_CC_CHANNEL0, time_ticks, NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK, true);
    nrfx_timer_enable(&My_Timer0);

    while (true)
    {
        if (!nrf_gpio_pin_read(BUTTON1))
        {
            nrf_delay_ms(50);
            if (!nrf_gpio_pin_read(BUTTON1))
            {
                nrfx_timer_pause(&My_Timer0);
                nrf_gpio_pin_clear(LED1);
                nrf_gpio_pin_clear(LED2);
                nrf_gpio_pin_clear(LED3);
                nrf_gpio_pin_clear(LED4);
                nrfx_timer_clear(&My_Timer0);
                nrfx_timer_resume(&My_Timer0);
            }
        }
        if (!nrf_gpio_pin_read(BUTTON2))
        {
            nrf_delay_ms(50);
            if (!nrf_gpio_pin_read(BUTTON2))
            {
                nrfx_timer_pause(&My_Timer0);
                nrf_gpio_pin_clear(LED1);
                nrf_gpio_pin_clear(LED2);
                nrf_gpio_pin_clear(LED3);
                nrf_gpio_pin_clear(LED4);
                time_ticks = nrfx_timer_ms_to_ticks(&My_Timer0, 500);
                nrfx_timer_extended_compare(&My_Timer0, NRF_TIMER_CC_CHANNEL0, time_ticks, NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK, true);
                nrfx_timer_resume(&My_Timer0);
            }
        }
        if (!nrf_gpio_pin_read(BUTTON3))
        {
            nrf_delay_ms(50);
            if (!nrf_gpio_pin_read(BUTTON3))
            {
                nrfx_timer_pause(&My_Timer0);
                nrf_gpio_pin_clear(LED1);
                nrf_gpio_pin_clear(LED2);
                nrf_gpio_pin_clear(LED3);
                nrf_gpio_pin_clear(LED4);
                time_ticks = nrfx_timer_ms_to_ticks(&My_Timer0, 1000);
                nrfx_timer_extended_compare(&My_Timer0, NRF_TIMER_CC_CHANNEL0, time_ticks, NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK, true);
                nrfx_timer_resume(&My_Timer0);
            }
        }
        if (!nrf_gpio_pin_read(BUTTON4))
        {
            nrf_delay_ms(50);
            if (!nrf_gpio_pin_read(BUTTON4))
            {
                nrfx_timer_pause(&My_Timer0);
                nrf_gpio_pin_clear(LED1);
                nrf_gpio_pin_clear(LED2);
                nrf_gpio_pin_clear(LED3);
                nrf_gpio_pin_clear(LED4);
                time_ticks = nrfx_timer_ms_to_ticks(&My_Timer0, 2000);
                nrfx_timer_extended_compare(&My_Timer0, NRF_TIMER_CC_CHANNEL0, time_ticks, NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK, true);
                nrfx_timer_resume(&My_Timer0);
            }
        }
    }
}