最近再做一个带蓝牙接口的血压计项目，项目中使用了STM32F10364引脚的MCU,在硬件设计中，因为外设较多，导致每个通用定时器至少有两个PWM输出引脚被占用，现在要控制RGB灯，只能用一个普通IO引脚模拟PWM输出。

相关的硬件电路设置如下：

GPIOA1------------------------------RGBBLUE灯

GPIOB1------------------------------RGBGREEN灯

GPIOD2------------------------------RGBRED灯

RGB灯采用了共阳极电路，所以在PWM的输出急性设置时，将极性设置为高电平，定时器的初始化如下图所示:

void initLedTimer( void ){

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

TIM_OCInitTypeDef TIM_OCInitStructure;

TIM_DeInit( TIM2 );

TIM_TimeBaseStructInit(&TIM_TimeBaseStructure );

TIM_TimeBaseStructure.TIM_Period =TIMER_PERIOD;

TIM_TimeBaseStructure.TIM_Prescaler =TIMER_PRESCALER;

TIM_TimeBaseStructure.TIM_ClockDivision= TIM_CKD_DIV1;  // 不分频

TIM_TimeBaseStructure.TIM_CounterMode =TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM2,&TIM_TimeBaseStructure);

TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStructure);

TIM_OCStructInit(&TIM_OCInitStructure );

TIM_OCInitStructure.TIM_OCMode =TIM_OCMode_PWM2;

TIM_OCInitStructure.TIM_OutputState =TIM_OutputState_Disable;

TIM_OCInitStructure.TIM_Pulse =DEFAULT_DUTY_CYCLE;

TIM_OCInitStructure.TIM_OCPolarity =TIM_OCPolarity_High;

//

TIM_OC1Init(TIM2,&TIM_OCInitStructure);

//

TIM_OC1PreloadConfig(TIM2,TIM_OCPreload_Enable);

//

TIM_OC2Init(TIM2,&TIM_OCInitStructure);

//

TIM_OC2PreloadConfig(TIM2,TIM_OCPreload_Enable);

//

TIM_OC3Init(TIM3,&TIM_OCInitStructure);

//

TIM_OC3PreloadConfig(TIM3,TIM_OCPreload_Enable);

//

TIM_OC4Init(TIM3,&TIM_OCInitStructure);

//

TIM_OC4PreloadConfig(TIM3,TIM_OCPreload_Enable);

//

TIM_OCStructInit(&TIM_OCInitStructure );

TIM_OCInitStructure.TIM_OCMode =TIM_OCMode_Timing;

TIM_OCInitStructure.TIM_Pulse =DEFAULT_DUTY_CYCLE;

//

TIM_OC2Init(TIM3,&TIM_OCInitStructure);

//

TIM_OC2PreloadConfig(TIM3,TIM_OCPreload_Enable);

// ARR重装载使能

TIM_ARRPreloadConfig(TIM2,ENABLE);

TIM_ARRPreloadConfig(TIM3,ENABLE);

//

TIM_ClearITPendingBit( TIM2,TIM_IT_Update );

TIM_ClearITPendingBit( TIM3,TIM_IT_Update | TIM_IT_CC2 );

//定时器2和3中断使能

TIM_ITConfig(TIM2,TIM_IT_Update,ENABLE);

TIM_ITConfig(TIM3,TIM_IT_Update |TIM_IT_CC2, ENABLE);

}

输出极性为高电平的意思就是说，假如说占空比为20%，那么他表示，低电平占整个周期20%的时间，反之如果设置极性为低电平，那么表示高电平占用整个周期的20%。

如何用GPIOD2模拟PWM波形呢？ 关键的地方就是同时必须使用定时器中断