STM32 定時器(二)——定時器產(chǎn)生不同頻率的PWM

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);
}

一個定時器一個通道，產(chǎn)生不同頻率

其它的設置都一樣，就是在主函數(shù)中修改一個參數(shù)，然后在定時器中斷中，根據(jù)這個參數(shù)，改變頻率。

#include "stm32libstm32f10x.h"
#include "hal.h"

volatile u16 Key_Value=1000; //用于保存按鍵相應的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) //按鍵前進按下 ,對應1kHz
{
Key_Value=6000;
}
else if(Get_Key_Down) //按鍵后退按下 ,對應2kHz
{
Key_Value=3000;
}
Delay_Ms(20); //10ms延時

if(Get_Key_Left) //按鍵左轉(zhuǎn)按下,對應3kHz
{
Key_Value=2000;
}
else if(Get_Key_Right) //按鍵右轉(zhuǎn)按下,對應4kHz
{
Key_Value=1500;
}
Delay_Ms(20); //10ms延時

if(Get_Key_Ctrl) //按鍵控制按下,對應5kHz
{
Key_Value=1200;
}
Delay_Ms(20); //10ms延時
}
}
}

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; //預分頻(時鐘分頻)72M/6=12M
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //向上計數(shù)
TIM_TimeBaseStructure.TIM_Period = 65535; //裝載值選擇最大
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;//反向通道無效
TIM_OCInitStructure.TIM_Pulse = Key_Value; //占空時間
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low; //輸出極性
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High; //互補端的極性
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：在計算PWM頻率的時候，TIMx的時鐘都是72Mhz，分頻后，因為翻轉(zhuǎn)兩次才能形成一個PWM波，因為，PWM的頻率是捕獲改變頻率的1/2。