stm32从小到大输出pwm

STM32是一款32位的微控制器，支持多种输出功能，包括PWM输出。下面是一些从小到大输出PWM的示例代码：

1. 通过直接操作寄存器来输出PWM

#include "stm32f10x.h"

int main(void)
{
  uint16_t duty_cycle = 0;
  
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
  
  GPIO_InitTypeDef GPIO_InitStruct;
  GPIO_InitStruct.GPIO_Pin = GPIO_Pin_0;
  GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOA, &GPIO_InitStruct);
  
  TIM_TimeBaseInitTypeDef TIM_InitStruct;
  TIM_InitStruct.TIM_Prescaler = 7200 - 1;  // 时钟预分频
  TIM_InitStruct.TIM_Period = 2000 - 1;     // 计数器周期
  TIM_InitStruct.TIM_ClockDivision = TIM_CKD_DIV1;  // 时钟分割
  TIM_InitStruct.TIM_CounterMode = TIM_CounterMode_Up;  // 计数器模式
  TIM_TimeBaseInit(TIM2, &TIM_InitStruct);
  
  TIM_OCInitTypeDef TIM_OC_InitStruct;
  TIM_OC_InitStruct.TIM_OCMode = TIM_OCMode_PWM1;  // PWM模式1
  TIM_OC_InitStruct.TIM_OutputState = TIM_OutputState_Enable;  // 输出使能
  TIM_OC_InitStruct.TIM_Pulse = duty_cycle;  // 占空比
  TIM_OC_InitStruct.TIM_OCPolarity = TIM_OCPolarity_High;  // 输出极性
  TIM_OC1Init(TIM2, &TIM_OC_InitStruct);
  
  TIM_Cmd(TIM2, ENABLE);  // 开启计数器
  
  while (1)
  {
    for (duty_cycle = 0; duty_cycle <= 2000; duty_cycle += 100)
    {
      TIM_SetCompare1(TIM2, duty_cycle);  // 更新占空比
      delay(100);  // 延时
    }
  }
}

2. 利用库函数来输出PWM

#include "stm32f10x.h"

int main(void)
{
  uint16_t duty_cycle = 0;
  
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
  
  GPIO_InitTypeDef GPIO_InitStruct;
  GPIO_InitStruct.GPIO_Pin = GPIO_Pin_0;
  GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOA, &GPIO_InitStruct);
  
  TIM_TimeBaseInitTypeDef TIM_InitStruct;
  TIM_InitStruct.TIM_Prescaler = 7200 - 1;  // 时钟预分频
  TIM_InitStruct.TIM_Period = 2000 - 1;     // 计数器周期
  TIM_InitStruct.TIM_ClockDivision = TIM_CKD_DIV1;  // 时钟分割
  TIM_InitStruct.TIM_CounterMode = TIM_CounterMode_Up;  // 计数器模式
  TIM_TimeBaseInit(TIM2, &TIM_InitStruct);
  
  TIM_OCInitTypeDef TIM_OC_InitStruct;
  TIM_OC_InitStruct.TIM_OCMode = TIM_OCMode_PWM1;  // PWM模式1
  TIM_OC_InitStruct.TIM_OutputState = TIM_OutputState_Enable;  // 输出使能
  TIM_OC_InitStruct.TIM_Pulse = duty_cycle;  // 占空比
  TIM_OC_InitStruct.TIM_OCPolarity = TIM_OCPolarity_High;  // 输出极性
  TIM_OC1Init(TIM2, &TIM_OC_InitStruct);
  
  TIM_Cmd(TIM2, ENABLE);  // 开启计数器
  
  while (1)
  {
    for (duty_cycle = 0; duty_cycle <= 2000; duty_cycle += 100)
    {
      TIM_OC1Init(TIM2, &TIM_OC_InitStruct);  // 更新占空比
      delay(100);  // 延时
    }
  }
}

以上两段代码均可实现从小到大输出PWM的功能。其中，第一段代码直接操作寄存器来配置PWM输出，第二段代码利用了库函数来简化操作。