基于STM32的奥运会倒计时代码

以下是一个基于STM32的奥运会倒计时的代码示例：

#include "stm32f10x.h"
#include "stm32f10x_rcc.h"
#include "stm32f10x_tim.h"
#include "stm32f10x_gpio.h"
#include "stm32f10x_usart.h"
#include "stdio.h"

#define LED_PORT GPIOB
#define LED_PIN GPIO_Pin_1

TIM_TimeBaseInitTypeDef timerInitStructure;
NVIC_InitTypeDef nvicStructure;
USART_InitTypeDef usartInitStructure;

void initLED(void);
void initTimer(void);
void initUSART(void);
void sendString(char *str);

int main(void)
{
    SystemInit();
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);

    initLED();
    initTimer();
    initUSART();

    while (1);
}

void initLED(void)
{
    GPIO_InitTypeDef gpioStructure;
    gpioStructure.GPIO_Pin = LED_PIN;
    gpioStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    gpioStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(LED_PORT, &gpioStructure);
}

void initTimer(void)
{
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

    timerInitStructure.TIM_Prescaler = 7200 - 1; // 1秒钟计数次数
    timerInitStructure.TIM_CounterMode = TIM_CounterMode_Down; // 向下计数模式
    timerInitStructure.TIM_Period = 60 * 60 * 24 - 1; // 计数周期为1天
    timerInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseInit(TIM2, &timerInitStructure);

    TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);

    nvicStructure.NVIC_IRQChannel = TIM2_IRQn;
    nvicStructure.NVIC_IRQChannelPreemptionPriority = 0;
    nvicStructure.NVIC_IRQChannelSubPriority = 0;
    nvicStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&nvicStructure);

    TIM_Cmd(TIM2, ENABLE);
}

void initUSART(void)
{
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_USART1, ENABLE);

    GPIO_InitTypeDef gpioStructure;
    gpioStructure.GPIO_Pin = GPIO_Pin_9;
    gpioStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    gpioStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &gpioStructure);

    gpioStructure.GPIO_Pin = GPIO_Pin_10;
    gpioStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA, &gpioStructure);

    usartInitStructure.USART_BaudRate = 115200;
    usartInitStructure.USART_WordLength = USART_WordLength_8b;
    usartInitStructure.USART_StopBits = USART_StopBits_1;
    usartInitStructure.USART_Parity = USART_Parity_No;
    usartInitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    usartInitStructure.USART_Mode = USART_Mode_Tx;
    USART_Init(USART1, &usartInitStructure);
    USART_Cmd(USART1, ENABLE);
}

void TIM2_IRQHandler(void)
{
    if (TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET)
    {
        TIM_ClearITPendingBit(TIM2, TIM_IT_Update);

        int days = TIM_GetCounter(TIM2) / 86400;
        int hours = (TIM_GetCounter(TIM2) - days * 86400) / 3600;
        int minutes = (TIM_GetCounter(TIM2) - days * 86400 - hours * 3600) / 60;
        int seconds = TIM_GetCounter(TIM2) - days * 86400 - hours * 3600 - minutes * 60;

        char buffer[50];
        sprintf(buffer, "倒计时：%d天 %02d:%02d:%02d\r\n", days, hours, minutes, seconds);
        sendString(buffer);

        if (TIM_GetCounter(TIM2) == 0)
        {
            GPIO_SetBits(LED_PORT, LED_PIN);
        }
    }
}

void sendString(char *str)
{
    while (*str)
    {
        USART_SendData(USART1, *str++);
        while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);
    }
}

这个代码使用了STM32的定时器和串口模块实现了一个倒计时功能。在主函数中初始化了LED、定时器和串口模块，然后进入了一个死循环。定时器的计数周期为1天，每次计数完成后会触发一个中断，在中断处理函数中计算倒计时并通过串口发送到电脑上。当倒计时结束时，会点亮一个LED。