在keil上写一个stm32按键调节pwm占空比程序

好的，下面是一个简单的示例代码，可以通过按键来调节PWM输出的占空比。该代码使用Keil MDK-ARM开发环境，目标芯片为STM32F103C8T6。假设你已经配置好了时钟和GPIO引脚。

#include "stm32f10x.h"

#define PWM_PERIOD      1000    // PWM周期为1000个计数器脉冲
#define BUTTON_DELAY    50      // 按键消抖延时

void TIM3_PWM_Init(void);
void TIM3_IRQHandler(void);
void Delay(uint32_t nCount);

int main(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;
    EXTI_InitTypeDef EXTI_InitStructure;

    // 配置按键所在GPIO口
    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);

    // 配置TIM3为PWM输出模式
    TIM3_PWM_Init();

    // 配置按键中断
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);

    GPIO_EXTILineConfig(GPIO_PortSourceGPIOA, GPIO_PinSource0);

    EXTI_InitStructure.EXTI_Line = EXTI_Line0;
    EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
    EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising_Falling;
    EXTI_InitStructure.EXTI_LineCmd = ENABLE;
    EXTI_Init(&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);

    while(1)
    {
        // 等待按键中断
    }
}

void TIM3_PWM_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_OCInitTypeDef TIM_OCInitStructure;

    // 配置TIM3所在GPIO口
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    // 配置TIM3时钟
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

    TIM_TimeBaseStructure.TIM_Period = PWM_PERIOD - 1;
    TIM_TimeBaseStructure.TIM_Prescaler = 71;
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

    // 配置TIM3通道1为PWM输出模式
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_Pulse = 0;
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OC1Init(TIM3, &TIM_OCInitStructure);

    TIM_Cmd(TIM3, ENABLE);

    TIM_ITConfig(TIM3, TIM_IT_Update, ENABLE);
    NVIC_EnableIRQ(TIM3_IRQn);
}

void TIM3_IRQHandler(void)
{
    static uint32_t cnt = 0;
    static uint32_t duty = 0;

    if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET)
    {
        TIM_ClearITPendingBit(TIM3, TIM_IT_Update);

        if (cnt++ >= 10)
        {
            cnt = 0;

            // 按键检测
            if (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0) == RESET)
            {
                Delay(BUTTON_DELAY);

                if (GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0) == RESET)
                {
                    duty += 100;
                    if (duty >= PWM_PERIOD) duty = 0;
                }
            }

            // 更新PWM占空比
            TIM_SetCompare1(TIM3, duty);
        }
    }
}

void Delay(uint32_t nCount)
{
    uint32_t i;

    for (i = 0; i < nCount * 1000; i++);
}

void EXTI0_IRQHandler(void)
{
    EXTI_ClearITPendingBit(EXTI_Line0);
}

该代码使用TIM3作为PWM输出源，配置了GPIOB0作为PWM输出引脚。按键使用GPIOA0，通过外部中断触发。按键按下时会增加PWM的占空比，最大为PWM周期-1，再次按下则从0开始。

在main函数中，通过配置TIM3中断的方式定时进行按键检测和PWM占空比更新。具体实现可以参考TIM3_IRQHandler函数。