用定时器设计一个循环LED灯，用按键控制灯左右移动。写出代码

好的，以下是一个简单的基于STM32的代码实现示例：

#include "stm32f10x.h"

// 定义LED灯数量和移动方向
#define LED_NUM 8
#define LED_LEFT 0
#define LED_RIGHT 1

// 定义LED灯状态数组
uint8_t led_status[LED_NUM] = {0};

// 定义LED移动方向和当前位置
uint8_t led_dir = LED_LEFT;
uint8_t led_pos = 0;

// 定义按键状态和上一次按键状态
uint8_t key_state = 0;
uint8_t key_last_state = 0;

// 定义定时器周期和计数器
uint16_t timer_period = 1000;
uint16_t timer_count = 0;

// 定义定时器中断函数
void TIM2_IRQHandler(void)
{
    if (TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET)
    {
        // 清除定时器中断标志位
        TIM_ClearITPendingBit(TIM2, TIM_IT_Update);

        // 更新LED灯状态
        if (led_dir == LED_LEFT)
        {
            led_pos = (led_pos + 1) % LED_NUM;
        }
        else
        {
            led_pos = (led_pos - 1 + LED_NUM) % LED_NUM;
        }
        for (int i = 0; i < LED_NUM; i++)
        {
            if (i == led_pos)
            {
                led_status[i] = 1;
            }
            else
            {
                led_status[i] = 0;
            }
        }

        // 更新定时器计数器
        timer_count++;
    }
}

// 定义按键中断函数
void EXTI0_IRQHandler(void)
{
    if (EXTI_GetITStatus(EXTI_Line0) != RESET)
    {
        // 延时一段时间消除按键抖动
        for (int i = 0; i < 10000; i++);

        // 检测按键状态
        key_state = GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0);

        // 如果按键状态发生变化，则更新LED移动方向
        if (key_state != key_last_state)
        {
            led_dir = led_dir == LED_LEFT ? LED_RIGHT : LED_LEFT;
        }

        // 更新上一次按键状态
        key_last_state = key_state;

        // 清除按键中断标志位
        EXTI_ClearITPendingBit(EXTI_Line0);
    }
}

int main(void)
{
    // 初始化LED灯
    GPIO_InitTypeDef GPIO_InitStructure;
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3 | GPIO_Pin_4 | GPIO_Pin_5 | GPIO_Pin_6 | GPIO_Pin_7;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    // 初始化按键
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    // 初始化定时器
    TIM_TimeBaseInitTypeDef TIM_InitStructure;
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
    TIM_InitStructure.TIM_Period = timer_period - 1;
    TIM_InitStructure.TIM_Prescaler = 7199;
    TIM_InitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_InitStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_InitStructure);

    // 启动定时器中断
    NVIC_InitTypeDef NVIC_InitStructure;
    NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
    TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);

    // 初始化按键中断
    EXTI_InitTypeDef EXTI_InitStructure;
    NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
    EXTI_InitStructure.EXTI_Line = EXTI_Line0;
    EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
    EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;
    EXTI_InitStructure.EXTI_LineCmd = ENABLE;
    EXTI_Init(&EXTI_InitStructure);

    // 启动定时器
    TIM_Cmd(TIM2, ENABLE);

    // 循环处理
    while (1)
    {
        // 控制LED灯状态
        for (int i = 0; i < LED_NUM; i++)
        {
            GPIO_WriteBit(GPIOB, GPIO_Pin_0 + i, led_status[i] ? Bit_SET : Bit_RESET);
        }

        // 等待定时器中断或按键中断
        if (timer_count >= timer_period)
        {
            timer_count = 0;
        }
    }
}

这段代码实现了一个可以通过按键控制的循环LED灯。当按下按键时，LED灯会改变移动方向；当定时器中断发生时，LED灯会循环移动。需要注意的是，这段代码仅供参考，实际实现中可能需要根据具体硬件平台和开发环境进行适当修改。