今天看来定时器这一部分,现在做一下总结,STM32总共分有8个定时器,包括基本定时器,通用定时器和高级定时器,其中基本定时器为TIM6,TIM7;通用定时器为TIM2,TIM3,TIM4,TIM5;高级定时器包括TIM1和TIM8。
下面总结三种定时功能:
基本定时器:只能定时,只能上升计时,可产生中断,DMA请求和触发内部DAC。
通用定时器:可定时,输入捕捉,输出比较,编码器接口,可上下计数,同样可产生中断,DMA请求和触发内部DAC。
高级定时器:具有以上两者所有功能,有三相六步电机接口,刹车功能及用于PWM驱动的死区时间控制等。
定时器的时钟来源
下面来看一下TIM2的实例代码,产生一个时间基准
TIM2_Configuration(); void TIM2_Configuration(void) { TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure; RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2 , ENABLE); //TIM_DeInit(TIM2); TIM_TimeBaseStructure.TIM_Period=1000; TIM_TimeBaseStructure.TIM_Prescaler= 71; TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1; TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up; TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure); TIM_ClearFlag(TIM2, TIM_FLAG_Update); TIM_ITConfig(TIM2,TIM_IT_Update,ENABLE); TIM_Cmd(TIM2, ENABLE); RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2 , DISABLE); }
接下来是TIM2产生PWM势力代码:(代码为4个IO产生占空比不同的方波)
static void TIM3_GPIO_Config(void) { GPIO_InitTypeDef GPIO_InitStructure; RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB, ENABLE); /*GPIOA Configuration: TIM3 channel 1 and 2 as alternate function push-pull */ GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(GPIOA, &GPIO_InitStructure); /*GPIOB Configuration: TIM3 channel 3 and 4 as alternate function push-pull */ GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1; GPIO_Init(GPIOB, &GPIO_InitStructure); }
static void TIM3_Mode_Config(void) { TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure; TIM_OCInitTypeDef TIM_OCInitStructure; /* PWMÐźŵçƽÌø±äÖµ */ u16 CCR1_Val = 500; u16 CCR2_Val = 375; u16 CCR3_Val = 250; u16 CCR4_Val = 125; /* ----------------------------------------------------------------------- TIM3 Channel1 duty cycle = (TIM3_CCR1/ TIM3_ARR+1)* 100% = 50% TIM3 Channel2 duty cycle = (TIM3_CCR2/ TIM3_ARR+1)* 100% = 37.5% TIM3 Channel3 duty cycle = (TIM3_CCR3/ TIM3_ARR+1)* 100% = 25% TIM3 Channel4 duty cycle = (TIM3_CCR4/ TIM3_ARR+1)* 100% = 12.5% ----------------------------------------------------------------------- */ /* Time base configuration */ TIM_TimeBaseStructure.TIM_Period = 999; TIM_TimeBaseStructure.TIM_Prescaler = 0; TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1 ; TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); /* PWM1 Mode configuration: Channel1 */ TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; TIM_OCInitStructure.TIM_Pulse = CCR1_Val; TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; TIM_OC1Init(TIM3, &TIM_OCInitStructure); TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable); /* PWM1 Mode configuration: Channel2 */ TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; TIM_OCInitStructure.TIM_Pulse = CCR2_Val; TIM_OC2Init(TIM3, &TIM_OCInitStructure); TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable); /* PWM1 Mode configuration: Channel3 */ TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; TIM_OCInitStructure.TIM_Pulse = CCR3_Val; TIM_OC3Init(TIM3, &TIM_OCInitStructure); TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable); /* PWM1 Mode configuration: Channel4 */ TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; TIM_OCInitStructure.TIM_Pulse = CCR4_Val; TIM_OC4Init(TIM3, &TIM_OCInitStructure); TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable); TIM_ARRPreloadConfig(TIM3, ENABLE); /* TIM3 enable counter */ TIM_Cmd(TIM3, ENABLE); }