【STM32F407 PWM配置和应用指南 】

PWM基本概念

PWM（脉冲宽度调制）是一种通过快速开关数字信号来控制模拟电路的技术，通过改变脉冲的占空比来控制平均电压。STM32F407的定时器外设可以生成PWM信号。

STM32F407 PWM配置步骤

1. 定时器时钟使能

首先需要使能定时器的时钟：

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); // 对于TIM3
// 或者
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE); // 对于高级定时器如TIM1

2. GPIO配置

配置用于PWM输出的GPIO引脚：

GPIO_InitTypeDef GPIO_InitStructure;

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6; // 例如TIM3_CH1在PC6
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_Init(GPIOC, &GPIO_InitStructure);

// 配置引脚复用功能
GPIO_PinAFConfig(GPIOC, GPIO_PinSource6, GPIO_AF_TIM3);

3. 定时器基本配置

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

TIM_TimeBaseStructure.TIM_Period = 8399; // 自动重装载值
TIM_TimeBaseStructure.TIM_Prescaler = 0; // 预分频器
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

4. PWM输出通道配置

TIM_OCInitTypeDef TIM_OCInitStructure;

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_Pulse = 0; // 初始占空比
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OC1Init(TIM3, &TIM_OCInitStructure);
TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);

5. 使能定时器

TIM_ARRPreloadConfig(TIM3, ENABLE); // 使能ARR预装载
TIM_Cmd(TIM3, ENABLE); // 使能定时器

// 对于高级定时器（如TIM1）还需要以下代码
TIM_CtrlPWMOutputs(TIM1, ENABLE);

PWM频率和占空比计算

PWM频率计算

PWM频率由以下公式决定：

PWM频率 = 定时器时钟频率 / ((Prescaler + 1) * (Period + 1))

例如，对于84MHz时钟，Prescaler=0，Period=8399：

PWM频率 = 84,000,000 / (1 * 8400) = 10,000 Hz (10kHz)

占空比设置

占空比通过改变TIM_Pulse值来设置：

占空比 = (TIM_Pulse + 1) / (Period + 1)

例如，要设置50%占空比：

TIM_SetCompare1(TIM3, 4199); // (8400 / 2) - 1

PWM应用示例

控制LED亮度

void PWM_LED_Init(void)
{
    // 初始化代码如上...
    
    // 设置PWM频率为1kHz
    TIM_TimeBaseStructure.TIM_Period = 83999; // 84MHz/84000 = 1kHz
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
    
    // 初始占空比50%
    TIM_SetCompare1(TIM3, 41999);
}

// 改变亮度
void Set_LED_Brightness(uint8_t brightness) // brightness: 0-100
{
    uint32_t pulse = (brightness * 83999) / 100;
    TIM_SetCompare1(TIM3, pulse);
}

控制电机速度

void PWM_Motor_Init(void)
{
    // 初始化代码...
    
    // 设置PWM频率为20kHz
    TIM_TimeBaseStructure.TIM_Period = 4199; // 84MHz/4200 = 20kHz
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
    
    // 初始速度为0
    TIM_SetCompare1(TIM3, 0);
}

void Set_Motor_Speed(uint8_t speed) // speed: 0-100
{
    uint32_t pulse = (speed * 4199) / 100;
    TIM_SetCompare1(TIM3, pulse);
}

使用HAL库配置PWM

// 1. 定时器句柄声明
TIM_HandleTypeDef htim3;
TIM_OC_InitTypeDef sConfigOC;

// 2. 定时器基本配置
htim3.Instance = TIM3;
htim3.Init.Prescaler = 0;
htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
htim3.Init.Period = 8399;
htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
HAL_TIM_PWM_Init(&htim3);

// 3. PWM通道配置
sConfigOC.OCMode = TIM_OCMODE_PWM1;
sConfigOC.Pulse = 0;
sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
HAL_TIM_PWM_ConfigChannel(&htim3, &sConfigOC, TIM_CHANNEL_1);

// 4. 启动PWM
HAL_TIM_PWM_Start(&htim3, TIM_CHANNEL_1);

// 改变占空比
__HAL_TIM_SET_COMPARE(&htim3, TIM_CHANNEL_1, 4200); // 设置50%占空比

高级应用技巧

互补PWM输出（用于电机驱动）

// 配置主输出
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;
TIM_OCInitStructure.TIM_Pulse = 0;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;
TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;
TIM_OC1Init(TIM1, &TIM_OCInitStructure);

// 使能死区时间
TIM_BDTRInitTypeDef TIM_BDTRInitStructure;
TIM_BDTRInitStructure.TIM_OSSRState = TIM_OSSRState_Enable;
TIM_BDTRInitStructure.TIM_OSSIState = TIM_OSSIState_Enable;
TIM_BDTRInitStructure.TIM_LOCKLevel = TIM_LOCKLevel_1;
TIM_BDTRInitStructure.TIM_DeadTime = 0x54; // 设置死区时间
TIM_BDTRInitStructure.TIM_Break = TIM_Break_Enable;
TIM_BDTRInitStructure.TIM_BreakPolarity = TIM_BreakPolarity_High;
TIM_BDTRInitStructure.TIM_AutomaticOutput = TIM_AutomaticOutput_Enable;
TIM_BDTRConfig(TIM1, &TIM_BDTRInitStructure);

TIM_CtrlPWMOutputs(TIM1, ENABLE);

多通道PWM同步

// 配置多个通道
TIM_OC1Init(TIM3, &TIM_OCInitStructure);
TIM_OC2Init(TIM3, &TIM_OCInitStructure);
TIM_OC3Init(TIM3, &TIM_OCInitStructure);

// 使用主从模式同步多个定时器
TIM_SelectMasterSlaveMode(TIM3, TIM_MasterSlaveMode_Enable);
TIM_SelectOutputTrigger(TIM3, TIM_TRGOSource_Update);

调试技巧

1. 使用示波器检查PWM波形是否符合预期
2. 检查时钟配置是否正确
3. 确保GPIO引脚复用功能配置正确
4. 验证预分频器和自动重装载值计算是否正确
5. 检查是否有其他外设冲突使用同一定时器

通过以上步骤和示例，您可以在STM32F407上成功配置和应用PWM功能。