TIMER门控模式控制PWM输出长度
参照一些网友代码做了些修改，由TIM4来控制TIM2的PWM输出长度，
采用主从的门控模式，即TIM4输出高时候TIM2使能输出
//TIM2 PWM输出，由TIM4来控制其输出与停止 //frequency_tim2：TIM2 PWM输出周期：KHz //duty_tim2：TIM2 PWM占空比 0-100 //period_tim4: TIM4控制TIM2总周期，单位0.1ms //duty_tim4: TIM4控制TIM2输出时间，单位0.1ms void TIM2_CH3_PA2_PWM_TIM4_CH4_GATE( unsigned short int frequency_tim2, char duty_tim2, unsigned short int period_tim4, unsigned short int duty_tim4 ) { GPIO_InitTypeDef GPIO_InitStructure; TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure; TIM_OCInitTypeDef TIM_OCInitStructure; RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM2 | RCC_APB1Periph_TIM4, ENABLE ); //使能定时器2时钟 RCC_APB2PeriphClockCmd( RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE ); //使能GPIO外设和AFIO复用功能模块时钟 //设置该引脚为复用输出功能,输出TIM2 CH3的PWM脉冲波形 GPIOA.2 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2; //TIM2_CH3 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //复用推挽输出 GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init( GPIOA, &GPIO_InitStructure ); //初始化GPIO //初始化TIM2 TIM_TimeBaseStructure.TIM_Period = ( 1000 / frequency_tim2 ); //设置在下一个更新事件装入活动的自动重装载寄存器周期的值,本身频率为1MHz，又分频器设置的下面一行 TIM_TimeBaseStructure.TIM_Prescaler = ( 72 - 1 ); //设置用来作为TIMx时钟频率除数的预分频值，72MHz/72=1MHz TIM_TimeBaseStructure.TIM_ClockDivision = 0; //设置时钟分割:TDTS = Tck_tim TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上计数模式 TIM_TimeBaseInit( TIM2, &TIM_TimeBaseStructure ); //根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位 //初始化TIM2 Channel3 PWM模式 TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; //选择定时器模式:TIM脉冲宽度调制模式2 TIM_OCInitStructure.TIM_Pulse = ( 10 * duty_tim2 / frequency_tim2 ); //(TIM_Period)*(duty/100) --> (1000/period)*(duty/100) TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //比较输出使能 TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //输出极性:TIM输出比较极性高 TIM_OC3Init( TIM2, &TIM_OCInitStructure ); //根据T指定的参数初始化外设TIM2 OC3 TIM_OC3PreloadConfig( TIM2, TIM_OCPreload_Enable ); //使能TIM2在CCR3上的预装载寄存器 TIM_Cmd( TIM2, ENABLE ); //使能TIM2 //初始化TIM4 TIM_TimeBaseStructure.TIM_Period = period_tim4; //设置在下一个更新事件装入活动的自动重装载寄存器周期的值,本身频率为1MHz，又分频器设置的下面一行 TIM_TimeBaseStructure.TIM_Prescaler = ( 7200 - 1 ); //设置用来作为TIMx时钟频率除数的预分频值，72MHz/72=1MHz TIM_TimeBaseStructure.TIM_ClockDivision = 0; //设置时钟分割:TDTS = Tck_tim TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上计数模式 TIM_TimeBaseInit( TIM4, &TIM_TimeBaseStructure ); //根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位 //初始化TIM4 Channel4 PWM模式 TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; //选择定时器模式:TIM脉冲宽度调制模式2 TIM_OCInitStructure.TIM_Pulse = duty_tim4; //(TIM_Period)*(duty/100) --> (1000/period)*(duty/100) TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //比较输出使能 TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //输出极性:TIM输出比较极性高 TIM_OC4Init( TIM4, &TIM_OCInitStructure ); //根据T指定的参数初始化外设TIM4 OC4 TIM_OC4PreloadConfig( TIM4, TIM_OCPreload_Enable ); //使能TIM4在CCR4上的预装载寄存器 TIM_Cmd( TIM4, ENABLE ); //使能TIM4 TIM_SelectInputTrigger( TIM2, TIM_TS_ITR3 ); //选择有效输入端 ,查表得知TIM4对于TIM2是ITR3 TIM_SelectSlaveMode( TIM2, TIM_SlaveMode_Gated ); //配置为主从复位模式 TIM_SelectOutputTrigger( TIM4, TIM_TRGOSource_OC4Ref ); /* Enable timer's master/slave work mode */ TIM_SelectMasterSlaveMode( TIM2, TIM_MasterSlaveMode_Enable ); //Slave TIM_SelectMasterSlaveMode( TIM4, TIM_MasterSlaveMode_Enable ); //Master }
