STM32学习笔记2（TIM增强模块向上溢出 & 输出比较）

TIM模块定时器向上溢出 & 输出比较

首先我们必须肯定ST公司的实力，也承认STM32的确是一款非常不错的Cortex-M3核单片机，但是，他的手册实在是让人觉得无法理解，尤其是其中的TIM模块，没有条理可言，看了两天几乎还是不知所云，让人很是郁闷。同时配套的固件库的说明也很难和手册上的寄存器对应起来，研究起来非常费劲！功能强大倒是真的，但至少也应该配套一个让人看的明白的说明吧~~
两天时间研究了STM32定时器的最最基础的部分，把定时器最基础的两个功能实现了，余下的功能有待继续学习。
首先有一点需要注意：FWLib固件库目前的最新版应该是V2.0.x，V1.0.x版本固件库中，TIM1模块被独立出来，调用的函数与其他定时器不同；在V2.0系列版本中，取消了TIM1.h，所有的TIM模块统一调用TIM.h即可。网络上流传的各种代码有许多是基于v1版本的固件库，在移植到v2版本固件库时，需要做些修改。本文的所有程序都是基于V2.0固件库。

以下是定时器向上溢出示例代码：

C语言: TIM1模块产生向上溢出事件
//Step1.时钟设置：启动TIM1
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);

//Step2.中断NVIC设置：允许中断，设置优先级
NVIC_InitStructure.NVIC_IRQChannel = TIM1_UP_IRQChannel;     //更新事件
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;    //抢占优先级0
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;           //响应优先级1
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;              //允许中断
NVIC_Init(&NVIC_InitStructure);                              //写入设置

//Step3.TIM1模块设置
void TIM_Configuration(void)
{
TIM_TimeBaseInitTypeDef TIM_BaseInitStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;

//TIM1 使用内部时钟
//TIM_InternalClockConfig(TIM1);

//TIM1基本设置
//设置预分频器分频系数71，即APB2=72M, TIM1_CLK=72/72=1MHz
//TIM_Period（TIM1_ARR）=1000，计数器向上计数到1000后产生更新事件，计数值归零
//向上计数模式
//TIM_RepetitionCounter(TIM1_RCR)=0，每次向上溢出都产生更新事件
TIM_BaseInitStructure.TIM_Period = 1000;
TIM_BaseInitStructure.TIM_Prescaler = 71;
TIM_BaseInitStructure.TIM_ClockDivision = 0;
TIM_BaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_BaseInitStructure.TIM_RepetitionCounter = 0;
TIM_TimeBaseInit(TIM1, &TIM_BaseInitStructure);

//清中断，以免一启用中断后立即产生中断
TIM_ClearFlag(TIM1, TIM_FLAG_Update);
//使能TIM1中断源
TIM_ITConfig(TIM1, TIM_IT_Update, ENABLE);

//TIM1总开关：开启
TIM_Cmd(TIM1, ENABLE);
}

//Step4.中断服务子程序：
void TIM1_UP_IRQHandler(void)
{
GPIOC->ODR ^= (1<<4);                          //闪灯
TIM_ClearITPendingBit(TIM1, TIM_FLAG_Update); //清中断
}

下面是输出比较功能实现TIM1_CH1管脚输出指定频率的脉冲：

C语言: TIM1模块实现输出比较，自动翻转并触发中断
//Step1.启动TIM1,同时还要注意给相应功能管脚启动时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

//Step2. PA.8口设置为TIM1的OC1输出口
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);

//Step3.使能TIM1的输出比较匹配中断
NVIC_InitStructure.NVIC_IRQChannel = TIM1_CC_IRQChannel;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

//Step4. TIM模块设置
void TIM_Configuration(void)
{
     TIM_TimeBaseInitTypeDef TIM_BaseInitStructure;
     TIM_OCInitTypeDef TIM_OCInitStructure;

     //TIM1基本计数器设置
     TIM_BaseInitStructure.TIM_Period = 0xffff;                       //这里必须是65535
     TIM_BaseInitStructure.TIM_Prescaler = 71;                        //预分频71，即72分频，得1M
     TIM_BaseInitStructure.TIM_ClockDivision = 0;
     TIM_BaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
     TIM_BaseInitStructure.TIM_RepetitionCounter = 0;
     TIM_TimeBaseInit(TIM1, &TIM_BaseInitStructure);

     //TIM1_OC1模块设置
     TIM_OCStructInit(& TIM_OCInitStructure);
     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle;              //管脚输出模式：翻转
     TIM_OCInitStructure.TIM_Pulse = 2000;                            //翻转周期：2000个脉冲
     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;    //使能TIM1_CH1通道
     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;        //输出为正逻辑
     TIM_OC1Init(TIM1, &TIM_OCInitStructure);                         //写入配置

     //清中断
     TIM_ClearFlag(TIM1, TIM_FLAG_CC1);

     //TIM1中断源设置，开启相应通道的捕捉比较中断
     TIM_ITConfig(TIM1, TIM_IT_CC1, ENABLE);

     //TIM1开启
     TIM_Cmd(TIM1, ENABLE);
     //通道输出使能
     TIM_CtrlPWMOutputs(TIM1, ENABLE);
}

Step5.中断服务子程序
void TIM1_CC_IRQHandler(void)
{
     u16 capture;
     if(TIM_GetITStatus(TIM1, TIM_IT_CC1) == SET)
     {
         TIM_ClearITPendingBit(TIM1, TIM_IT_CC1 );
         capture = TIM_GetCapture1(TIM1);
         TIM_SetCompare1(TIM1, capture + 2000);
         //这里解释下:
         //将TIM1_CCR1的值增加2000，使得下一个TIM事件也需要2000个脉冲，
         //另一种方式是清零脉冲计数器
         //TIM_SetCounter(TIM2,0x0000);
     }
}

关于TIM的操作，要注意的是STM32处理器因为低功耗的需要，各模块需要分别独立开启时钟，所以，一定不要忘记给用到的模块和管脚使能时钟，因为这个原因，浪费了我好多时间阿~~！

TIM模块产生PWM

这个是STM32的PWM输出模式，STM32的TIM1模块是增强型的定时器模块，天生就是为电机控制而生，可以产生3组6路PWM，同时每组2路PWM为互补，并可以带有死区，可以用来驱动H桥。
下面的代码，是利用TIM1模块的1、2通道产生一共4路PWM的代码例子，类似代码也可以参考ST的固件库中相应example
C语言: TIM1模块产生PWM，带死区
   
//Step1.开启TIM和相应端口时钟
//启动GPIO
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB | \
                        RCC_APB2Periph_GPIOC | RCC_APB2Periph_GPIOD,\
                        ENABLE);
//启动AFIO
RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);
//启动TIM1
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);

//Step2. GPIO做相应设置，为AF输出
//PA.8/9口设置为TIM1的OC1输出口
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8 | GPIO_Pin_9;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);

//PB.13/14口设置为TIM1_CH1N和TIM1_CH2N输出口
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13 | GPIO_Pin_14;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOB, &GPIO_InitStructure);

//Step3. TIM模块初始化
void TIM_Configuration(void)
{
     TIM_TimeBaseInitTypeDef TIM_BaseInitStructure;
     TIM_OCInitTypeDef TIM_OCInitStructure;
     TIM_BDTRInitTypeDef TIM_BDTRInitStructure;

     //TIM1基本计数器设置（设置PWM频率）
     //频率=TIM1_CLK/(ARR+1)
     TIM_BaseInitStructure.TIM_Period = 1000-1;
     TIM_BaseInitStructure.TIM_Prescaler = 72-1;
     TIM_BaseInitStructure.TIM_ClockDivision = 0;
     TIM_BaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
     TIM_BaseInitStructure.TIM_RepetitionCounter = 0;
     TIM_TimeBaseInit(TIM1, &TIM_BaseInitStructure);
     //启用ARR的影子寄存器（直到产生更新事件才更改设置）
     TIM_ARRPreloadConfig(TIM1, ENABLE);

     //TIM1_OC1模块设置（设置1通道占空比）
     TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
     TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;
     TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
     TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;
     TIM_OCInitStructure.TIM_Pulse = 120;
     TIM_OC1Init(TIM1, &TIM_OCInitStructure);
     //启用CCR1寄存器的影子寄存器（直到产生更新事件才更改设置）
     TIM_OC1PreloadConfig(TIM1, TIM_OCPreload_Enable);

     //TIM2_OC2模块设置（设置2通道占空比）
     TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
     TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;
     TIM_OCInitStructure.TIM_Pulse = 680;
     TIM_OC2Init(TIM1, &TIM_OCInitStructure);
     //启用CCR2寄存器的影子寄存器（直到产生更新事件才更改设置）
     TIM_OC2PreloadConfig(TIM1, TIM_OCPreload_Enable);
  
     //死区设置
     TIM_BDTRInitStructure.TIM_OSSRState = TIM_OSSRState_Enable;
     TIM_BDTRInitStructure.TIM_OSSIState = TIM_OSSIState_Enable;
     TIM_BDTRInitStructure.TIM_LOCKLevel = TIM_LOCKLevel_OFF;
     TIM_BDTRInitStructure.TIM_DeadTime = 0x90;   //这里调整死区大小0-0xff
     TIM_BDTRInitStructure.TIM_Break = TIM_Break_Disable;
     TIM_BDTRInitStructure.TIM_BreakPolarity = TIM_BreakPolarity_High;
     TIM_BDTRInitStructure.TIM_AutomaticOutput = TIM_AutomaticOutput_Enable;
     TIM_BDTRConfig(TIM1, &TIM_BDTRInitStructure);
  
     //TIM1开启
     TIM_Cmd(TIM1, ENABLE);
     //TIM1_OC通道输出PWM（一定要加）
     TIM_CtrlPWMOutputs(TIM1, ENABLE);

}

其实，PWM模块还可以有很多花样可以玩，比方在异常时（如CPU时钟有问题），可以紧急关闭输出，以免发生电路烧毁等严重事故