一、概述
STM32F1系列的定时器可以分为3类:
1)高级定时器(TIM1,TIM8):16 位向上、向下、向上/向下自动装载计数器,可以产生DMA请求,有4组捕获/比较通道输出互补PWM信号;
2)通用定时器(TIM2~TIM5):16 位向上、向下、向上/向下自动装载计数器,可以产生DMA请求,有4组捕获/比较通道输出PWM信号但不能输出互补PWM信号;
3)基本定时器(TIM6,TIM7):16 位向上、向下、向上/向下自动装载计数器;
相关寄存器:
要使用STM32的高级定时器,使用定时中断、PWM输出或者输入捕获功能,一般需要用到TIMx_ARR(自动重装载寄存器)、TIMx_PSC(预分频寄存器)、TIMx_CR1/2(控制寄存器1/2)、TIMx_CNT(16位自动装载计数器)、TIMx_CCMR1/2(捕获/比较模式寄存器1/2)、TIMx_CCER(捕获/比较使能寄存器)、TIMx_CCR1~4(捕获/比较寄存器1~4)、TIMx_BDTR(刹车和死区寄存器);
二、例子
A、定时器中断例子
void TIM3_Init(uint16_t arr,uint16_t psc)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Perph_TIM3,ENABLE);//使能时钟
TIM_TimeBaseStructure.TIM_Period = arr;//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
TIM_TimeBaseStructure.TIM_Prescaler = psc;//设置用来作为TIM时钟频率除数的预分频值
TIM_TimeBaseStructure.TIM_ClockDivision = 0;//设置时钟分割
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;//TIM向上计数模式
TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStructure);
TIM_ITConfig(TIM3,TIM_IT_Update,ENABLE);//使能定时器3中断
NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQ;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
TIM_Cmd(TIM3,ENABLE);
}
void TIM3_IRQHandler(void)
{
if(TIM_GetITStatus(TIM3,TIM_IT_Update) != RESET)//检查指定的TIM中断发生
{
TIM_ClearPendingBit(TIM3,TIM_IT_Update);//清除中断标志
TestCounter++;
if(TestCounter >= 20)
{
TestCounter = 0;
TIM_SetCounter(TIM3,0);//清空计数器
TIM_SetAutoreload(TIM3,9999);//改变自动重装载值
}
}
}
B、PWM输出
void TIM1_PWMConfig(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1 | RCC_APB2Periph_GPIOA,ENABLE);
//设置该引脚为复用输出功能,输出TIM_CH1的PWM脉冲波形
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA,&GPIO_InitStructure);
TIM_TimeBaseStructure.TIM_Period = arr;
TIM_TimeBaseStructure.TIM_Prescaler = psc;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM1,&TIM_TimeBaseStructure);
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;//选择定时器模式:TIM脉冲宽度调制模式2:TIMx_CNT<TIMx_CCR1,通道1为有效电平
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;//比较输出使能
TIM_OCInitStructure.TIM_Pulse = 0;//设置待装入捕获比较寄存器的脉冲值
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;//输出极性:TIM输出比较极性高,即设置有效电平为高
TIM_OC1Init(TIM1,&TIM_OCInitStructure);
TIM_CtrlPWMOutputs(TIM1,ENABLE);//输出使能
TIM_OC1PreloadConfig(TIM1,TIM_OCPreload_Enable);//CH1预装载使能
TIM_ARRPreloadConfig(TIM1,ENABLE);//使能TIMx在ARR上的预装载寄存器
TIM_Cmd(TIM1,ENABLE);
}
注意:TIMx_CCMR寄存器总共有两个,TIMx_CCMR1控制CH1和CH2,TIMx_CCMR2控制CH3和CH4;高级定时器会需要用到TIMx_BDTR,一般我们较为关心MOE位(主输出使能位);
如:TIM_SetCompare1库函数可以实时改变CCR1的值,从而控制PWM输出;
C、输入捕获
时钟分割定义的是在定时器时钟频率(CK_INT)与数字滤波器(ETR,TIx)使用的采样频率之间的分频比例。
TIM_ClockDivision的参数如下表:
数字滤波器(ETR,TIx)是为了将ETR进来的分频后的信号滤波,保证通过信号频率不超过某个限定。
void TIM2_Cap_Init(uint16_t arr,uint16_t psc)
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_ICInitTypeDef TIM2_ICInitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2,ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);
GPIO_InitStructure.GPIO_Pin_0;
GPIO_InitStructure.GPIO_Mode_IPD;
GPIO_Init(GPIOA,&GPIO_InitStructure);
GPIO_ResetBits(GPIOA,GPIO_Pin_0);
//初始化定时器2
TIM_TimeBaseStructure.TIM_Period = arr;
TIM_TimeBaseStructure.TIM_Prescaler = psc;
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM2,&TIM_TimeBaseStructure);
//初始化输入捕获参数
TIM2_ICInitStructure.TIM_Channel = TIM_Channel_1;
TIM2_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
TIM2_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
TIM2_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
TIM2_ICInitStructure.TIM_ICFilter = 0x00;//配置输入滤波器为不滤波
TIM_ICInit(TIM2,&TIM2_ICInitStructure);
NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQ;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
TIM_ITConfig(TIM2,TIM_IT_Update | TIM_IT_CC1,ENABLE);//允许更新中断,允许CC1IE捕获中断
TIM_Cmd(TIM2,ENABLE);
}
uint8_t TIM2CH1_CAPTURE_STA = 0;//输入捕获状态
uint8_t TIM2CH1_CAPTURE_VAL;//输入捕获值
void TIM2_IRQHandler(void)
{
if((TIM2CH1_CAPTURE_STA & 0x80) == 0)//还未成功捕获
{
if(TIM_GetITStatus(TIM2,TIM_IT_Update) != RESET)
{
if(TIM2CH1_CAPTURE_STA & 0x40)//已经捕获到高电平
{
if((TIM2CH1_CAPTURE_STA & 0x3F) == 0x3F)//高电平太长了
{
TIM2CH1_CAPTURE_STA |= 0x80;//标记成功捕获一次
TIM2CH1_CAPTURE_VAL = 0xFFFF;
}
else TIM2CH1_CAPTURE_STA++;
}
}
if(TIM_GetITStatus(TIM2,TIM_IT_CC1) != RESET)//发生捕获事件
{
if(TIM2CH1_CAPTURE_STA & 0x40)//捕获一个下降沿
{
TIM2CH1_CAPTURE_STA |= 0x80;//标记成功捕获一次下降沿
TIM2CH1_CAPTURE_VAL = TIM_GetCapture1(TIM2);
TIM_OC1PolarityConfig(TIM2,TIM_ICPolarity_Rising);//重置为上升沿捕获
}
else
{
TIM2CH1_CAPTURE_STA = 0;//清零
TIM2CH1_CAPTURE_VAL = 0;
TIM_SetCounter(TIM2,0);
TIM2CH1_CAPTURE_STA |= 0x40;//标记捕获到上升沿
TIM_OC1PolarityConfig(TIM2,TIM_ICPolarity_Falling);//重置为下降沿捕获
}
}
}
TIM_ClearITPendingBit(TIM2,TIM_IT_CC1 | TIM_IT_Update);
}
extern uint8_t TIM2CH1_CAPTURE_STA;//输入捕获状态
extern uint8_t TIM2CH1_CAPTURE_VAL;//输入捕获值
void main(void)
{
u32 temp = 0;
...
...
while(1)
{
delay_ms(10);
if(TIM2CH1_CAPTURE_STA & 0x80)
{
temp = TIM2CH1_CAPTURE_STA & 0x3F;
temp *= 65535; //溢出总时间
temp += TIM2CH1_CAPTURE_VAL;//得到总的高电平时间
printf("High:%d us\r\n",temp);//打印
TIM2CH1_CAPTURE_STA = 0;
}
}
}
三、总结
提供几个简单的,实际项目中用得比较多的定时器例子参考交流,写得不好或者错误的请大佬指出,谢谢!