STM32 定时器(二)——定时器产生不同频率的PWM

 （1）使能定时器时钟：RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

 （2）定义相应的GPIO：

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2|GPIO_Pin_3|GPIO_Pin_4|GPIO_Pin_5|GPIO_Pin_6;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; //下拉接地，检测输入的高电平
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //50M时钟速度
GPIO_Init(GPIOA, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;  
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //50M时钟速度
GPIO_Init(GPIOA, &GPIO_InitStructure);

（3）如果是产生PWM（频率不变，占空比可变），记得打开PWM控制，在TIM_Configuration()中。

TIM_Cmd(TIM3,ENABLE);

TIM_CtrlPWMOutputs(TIM1,ENABLE);

利用定时器产生不同频率的PWM

   有时候，需要产生不同频率的PWM，这个时候，设置与产生相同PWM的程序，有关键的不一样。

（一）设置的原理

     利用改变定时器输出比较通道的捕获值，当输出通道捕获值产生中断时，在中断中将捕获值改变，这时，输出的I/O会产生一个电平翻转，利用这种办法，实现不同频率的PWM输出。

（二）关键设置

在定时器设置中：TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Disable);

在中断函数中： if (TIM_GetITStatus(TIM3, TIM_IT_CC2) != RESET)
     {
          TIM_ClearITPendingBit(TIM3, TIM_IT_CC2);
          capture = TIM_GetCapture2(TIM3);
          TIM_SetCompare2(TIM3, capture + Key_Value);
     }

一个定时器四个通道，分别产生不同频率（这个例子网上也有）

vu16 CCR1_Val = 32768;
vu16 CCR2_Val = 16384;
vu16 CCR3_Val = 8192;
vu16 CCR4_Val = 4096;

void TIM_Configuration(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

TIM_TimeBaseStructure.TIM_Period = 65535;         
TIM_TimeBaseStructure.TIM_Prescaler = 2;      
TIM_TimeBaseStructure.TIM_ClockDivision = 0;   
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle;      //PWM模式2
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //正向通道有效
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;//反向通道无效
TIM_OCInitStructure.TIM_Pulse = CCR1_Val;         //占空时间
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;    //输出极性
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;     //互补端的极性
TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;

TIM_OC1Init(TIM2,&TIM_OCInitStructure);        //通道1
TIM_OC1PreloadConfig(TIM2, TIM_OCPreload_Disable);

TIM_OCInitStructure.TIM_Pulse = CCR2_Val;         //占空时间
TIM_OC2Init(TIM2,&TIM_OCInitStructure);        //通道2
TIM_OC2PreloadConfig(TIM2, TIM_OCPreload_Disable);

TIM_OCInitStructure.TIM_Pulse = CCR3_Val;         //占空时间
TIM_OC3Init(TIM2,&TIM_OCInitStructure);        //通道3
TIM_OC3PreloadConfig(TIM2, TIM_OCPreload_Disable);

TIM_OCInitStructure.TIM_Pulse = CCR4_Val;         //占空时间
TIM_OC4Init(TIM2,&TIM_OCInitStructure);        //通道4
TIM_OC4PreloadConfig(TIM2, TIM_OCPreload_Disable);

TIM_Cmd(TIM2,ENABLE);


//TIM_CtrlPWMOutputs(TIM2,ENABLE);

TIM_ITConfig(TIM2, TIM_IT_CC1 | TIM_IT_CC2 | TIM_IT_CC3 | TIM_IT_CC4, ENABLE);

}

void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD, ENABLE);

GPIO_InitStructure.GPIO_Pin = 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_OD; //开漏输出
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //50M时钟速度
GPIO_Init(GPIOA, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0|GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_OD; //开漏输出
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //50M时钟速度
GPIO_Init(GPIOB, &GPIO_InitStructure);


GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0|GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;   //上拉输入
GPIO_Init(GPIOA, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;   //上拉输入
GPIO_Init(GPIOC, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;   //上拉输入
GPIO_Init(GPIOB, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_Init(GPIOA, &GPIO_InitStructure);
}

void NVIC_Configuration(void)
{
NVIC_InitTypeDef NVIC_InitStructure;

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);

NVIC_InitStructure.NVIC_IRQChannel=TIM2_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority=1;
NVIC_InitStructure.NVIC_IRQChannelCmd=ENABLE;
NVIC_Init(&NVIC_InitStructure);
}[page]

u16 capture = 0;
extern vu16 CCR1_Val;
extern vu16 CCR2_Val;
extern vu16 CCR3_Val;
extern vu16 CCR4_Val;

void TIM2_IRQHandler(void)
{

if (TIM_GetITStatus(TIM2, TIM_IT_CC1) != RESET)
{
    TIM_ClearITPendingBit(TIM2, TIM_IT_CC1 );
capture = TIM_GetCapture1(TIM2);
TIM_SetCompare1(TIM2, capture + CCR1_Val );
}


if (TIM_GetITStatus(TIM2, TIM_IT_CC2) != RESET)
{
     TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);
capture = TIM_GetCapture2(TIM2);
    TIM_SetCompare2(TIM2, capture + CCR2_Val);
}

if (TIM_GetITStatus(TIM2, TIM_IT_CC3) != RESET)
{
    TIM_ClearITPendingBit(TIM2, TIM_IT_CC3);
capture = TIM_GetCapture3(TIM2);
    TIM_SetCompare3(TIM2, capture + CCR3_Val);
}

if (TIM_GetITStatus(TIM2, TIM_IT_CC4) != RESET)
{
    TIM_ClearITPendingBit(TIM2, TIM_IT_CC4);
capture = TIM_GetCapture4(TIM2);
    TIM_SetCompare4(TIM2, capture + CCR4_Val);
}

一个定时器一个通道，产生不同频率

其它的设置都一样，就是在主函数中修改一个参数，然后在定时器中断中，根据这个参数，改变频率。

#include "stm32lib\stm32f10x.h"
#include "hal.h"

volatile u16 Key_Value=1000;   //用于保存按键相应的PWM波占空比值

int main(void)
{
ChipHalInit();
ChipOutHalInit();

while(1)
{  
   if( (!Get_Key_Up)&(!Get_Key_Down)&(!Get_Key_Left)&(!Get_Key_Right)&(!Get_Key_Ctrl) )
   {
    Key_Value=12000;
   }
   else
   {
    if(Get_Key_Up)     //按键前进按下 ,对应1kHz
    {
     Key_Value=6000;
    }
     else if(Get_Key_Down)   //按键后退按下 ,对应2kHz
     {
       Key_Value=3000;
     }
     Delay_Ms(20);      //10ms延时

    if(Get_Key_Left)    //按键左转按下,对应3kHz
    {
     Key_Value=2000;
    }
     else if(Get_Key_Right) //按键右转按下,对应4kHz
     {
      Key_Value=1500;
     }  
     Delay_Ms(20);      //10ms延时

    if(Get_Key_Ctrl)    //按键控制按下,对应5kHz
    {
      Key_Value=1200;
    }
    Delay_Ms(20);      //10ms延时
   }
}
}

extern volatile u16 Key_Value;
u16 capture=0;
void TIM3_IRQHandler(void)
{

if (TIM_GetITStatus(TIM3, TIM_IT_CC2) != RESET)
{
     TIM_ClearITPendingBit(TIM3, TIM_IT_CC2);
capture = TIM_GetCapture2(TIM3);
    TIM_SetCompare2(TIM3, capture + Key_Value);
}
}

void TIM3_Configuration(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

TIM_TimeBaseStructure.TIM_Prescaler = 5;       //预分频(时钟分频)72M/6=12M
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;   //向上计数
TIM_TimeBaseStructure.TIM_Period = 65535;        //装载值选择最大
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseStructure.TIM_RepetitionCounter = 0x0;
TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStructure);

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle;      //PWM模式2
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //正向通道有效
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;//反向通道无效
TIM_OCInitStructure.TIM_Pulse = Key_Value;         //占空时间
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;    //输出极性
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;     //互补端的极性
TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;

TIM_OC2Init(TIM3,&TIM_OCInitStructure);        //通道2
TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Disable);


TIM_Cmd(TIM3,ENABLE);


//TIM_CtrlPWMOutputs(TIM1,ENABLE);
TIM_ITConfig(TIM3, TIM_IT_CC2 , ENABLE);
}

注意：在计算PWM频率的时候，TIMx的时钟都是72Mhz，分频后，因为翻转两次才能形成一个PWM波，因为，PWM的频率是捕获改变频率的1/2。