当按键按下时开始记数,得到按键按下的时间,基于f407标准库,用定时器实现
时间: 2023-07-20 14:16:04 浏览: 39
好的,您可以使用下面的代码来实现这个功能,基于 f407 标准库,使用定时器 TIM2 实现计时:
```c
#include "stm32f4xx.h"
#include <stdio.h>
volatile uint32_t start_time = 0;
volatile uint32_t end_time = 0;
volatile uint32_t duration = 0;
volatile uint8_t key_pressed = 0;
void TIM2_IRQHandler(void)
{
if (TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET)
{
TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
if (key_pressed)
{
end_time = TIM_GetCounter(TIM2);
duration = end_time - start_time;
}
}
}
void EXTI0_IRQHandler(void)
{
if (EXTI_GetITStatus(EXTI_Line0) != RESET)
{
EXTI_ClearITPendingBit(EXTI_Line0);
if (!key_pressed)
{
start_time = TIM_GetCounter(TIM2);
key_pressed = 1;
}
else
{
end_time = TIM_GetCounter(TIM2);
duration = end_time - start_time;
key_pressed = 0;
printf("按键按下的时间为:%d 毫秒\n", duration);
}
}
}
void init_gpio(void)
{
GPIO_InitTypeDef GPIO_InitStruct;
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
GPIO_InitStruct.GPIO_Pin = GPIO_Pin_0;
GPIO_InitStruct.GPIO_Mode = GPIO_Mode_IN;
GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOA, &GPIO_InitStruct);
}
void init_timer(void)
{
TIM_TimeBaseInitTypeDef TIM_InitStruct;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
TIM_InitStruct.TIM_Period = 0xFFFFFFFF;
TIM_InitStruct.TIM_Prescaler = SystemCoreClock / 1000 - 1;
TIM_InitStruct.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_InitStruct.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM2, &TIM_InitStruct);
TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);
TIM_Cmd(TIM2, ENABLE);
}
void init_exti(void)
{
EXTI_InitTypeDef EXTI_InitStruct;
NVIC_InitTypeDef NVIC_InitStruct;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);
SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOA, EXTI_PinSource0);
EXTI_InitStruct.EXTI_Line = EXTI_Line0;
EXTI_InitStruct.EXTI_Mode = EXTI_Mode_Interrupt;
EXTI_InitStruct.EXTI_Trigger = EXTI_Trigger_Rising_Falling;
EXTI_InitStruct.EXTI_LineCmd = ENABLE;
EXTI_Init(&EXTI_InitStruct);
NVIC_InitStruct.NVIC_IRQChannel = EXTI0_IRQn;
NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 0x00;
NVIC_InitStruct.NVIC_IRQChannelSubPriority = 0x00;
NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStruct);
}
int main(void)
{
SystemInit();
init_gpio();
init_timer();
init_exti();
while (1)
{
// 等待按键中断
}
}
```
当您按下按键时,它会记录按键按下的时间,并当您释放按键时,它会计算出按键按下的时间,并将其打印到串口终端上。请注意,此代码中的时间以毫秒为单位进行计算,并使用 TIM2 定时器来实现计时和计数。