STM32开发板学习日记-[3] TIM定时器输出比较
使用Timer进行周期定时
在STM32的某些应用中，用户有周期性执行某些程序的要求，使用定时器可以产生固定的时间周期，满足 这样的需求。
STM32相关特征：
STM32高级定时器TIM1、TIM8，通用定时器TIM2、TIM3、TIM4、TIM5；
定时器最大时钟72MHz，配合预分频，提供灵活的时钟周期；
每个TIM有4个独立捕获/比较通道，DMA/中断功能；
通道工作在输出比较定时模式，一个TIM至多可以提供4个不同的定时周期。
原理
TIM某输出/捕获通道工作在输出比较定时模式
计数器计数至比较值时产生中断，在中断中刷新捕获比较寄存器，这样在相同时间间隔后可产生下一次中断
TIM2时钟设置为36MHz，预分频设置为2，使用输出比较-翻转模式（Output Compare Toggle Mode）。
TIM2计数器时钟可表达为：TIM2 counter clock = TIMxCLK / (Prescaler +1) = 12 MHz
设置TIM2_CCR1寄存器值为32768，则CC1更新频率为TIM2计数器时钟频率除以CCR1寄存器值，为366.2 Hz。因此，TIM2通道1可产生一个频率为183.1 Hz的周期信号。
同理，根据寄存器TIM2_CCR2 、TIM2_CCR3和 TIM2_CCR4的值，TIM2通道2可产生一个频率为366.3 Hz的周期信号；TIM2通道3可产生一个频率为732.4 Hz的周期信号；TIM2通道4可产生一个频率为1464.8 Hz的周期信号。
可以通过示波器观察各路输出。
#include "stm32f10x_lib.h"
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
vu16 CCR1_Val = 32768;
vu16 CCR2_Val = 16384;
vu16 CCR3_Val = 8192;
vu16 CCR4_Val = 4096;
ErrorStatus HSEStartUpStatus;
void RCC_Configuration(void);
void GPIO_Configuration(void);
void NVIC_Configuration(void);
int main(void)
{
#ifdef DEBUG
debug();
#endif
RCC_Configuration();
NVIC_Configuration();
GPIO_Configuration();
TIM_TimeBaseStructure.TIM_Period = 65535; //这里必须是65535
TIM_TimeBaseStructure.TIM_Prescaler = 2;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle; //管脚输出模式：翻转(TIM输出比较触发模式)
TIM_OCInitStructure.TIM_Channel = TIM_Channel_1;
TIM_OCInitStructure.TIM_Pulse = CCR1_Val; //翻转周期
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;//TIM输出比较极性低
TIM_OCInit(TIM2, &TIM_OCInitStructure);
TIM_OC1PreloadConfig(TIM2, TIM_OCPreload_Disable);//失能TIMx在CCR1上的预装载寄存器
TIM_OCInitStructure.TIM_Channel = TIM_Channel_2;
TIM_OCInitStructure.TIM_Pulse = CCR2_Val;
TIM_OCInit(TIM2, &TIM_OCInitStructure);
TIM_OC2PreloadConfig(TIM2, TIM_OCPreload_Disable);
TIM_OCInitStructure.TIM_Channel = TIM_Channel_3;
TIM_OCInitStructure.TIM_Pulse = CCR3_Val;
TIM_OCInit(TIM2, &TIM_OCInitStructure);
TIM_OC3PreloadConfig(TIM2, TIM_OCPreload_Disable);
TIM_OCInitStructure.TIM_Channel = TIM_Channel_4;
TIM_OCInitStructure.TIM_Pulse = CCR4_Val;
TIM_OCInit(TIM2, &TIM_OCInitStructure);
TIM_OC4PreloadConfig(TIM2, TIM_OCPreload_Disable);
TIM_Cmd(TIM2, ENABLE);
TIM_ITConfig(TIM2, TIM_IT_CC1 | TIM_IT_CC2 | TIM_IT_CC3 | TIM_IT_CC4, ENABLE);
while (1)
{
}
}
void RCC_Configuration(void)
{
RCC_DeInit();
RCC_HSEConfig(RCC_HSE_ON);
HSEStartUpStatus = RCC_WaitForHSEStartUp();
if(HSEStartUpStatus == SUCCESS)
{
FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
FLASH_SetLatency(FLASH_Latency_2);
RCC_HCLKConfig(RCC_SYSCLK_Div1);
RCC_PCLK2Config(RCC_HCLK_Div1);
RCC_PCLK1Config(RCC_HCLK_Div4);
RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);
RCC_PLLCmd(ENABLE);
while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET)
{
}
RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
while(RCC_GetSYSCLKSource() != 0x08)
{
}
}
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
}
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
}
void NVIC_Configuration(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
#ifdef VECT_TAB_RAM
NVIC_SetVectorTable(NVIC_VectTab_RAM, 0x0);
#else
NVIC_SetVectorTable(NVIC_VectTab_FLASH, 0x0);
#endif
NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQChannel;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
#ifdef DEBUG
void assert_failed(u8* file, u32 line)
{
while (1)
{
}
}
#endif
中断服务：
void TIM2_IRQHandler(void)
{
if (TIM_GetITStatus(TIM2, TIM_IT_CC1) != RESET)//检查指定的TIM中断发生与否
{
TIM_ClearITPendingBit(TIM2, TIM_IT_CC1 );//清除TIMx的中断待处理位
capture = TIM_GetCapture1(TIM2);
TIM_SetCompare1(TIM2, capture + CCR1_Val );//设置TIMx自动重装载寄存器值
//将TIM2_CC1的值增加CCR1_Val，使得下一个TIM事件也需要CCR1_Val个脉冲，
}
if (TIM_GetITStatus(TIM2, TIM_IT_CC2) != RESET)
{
TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);
capture = TIM_GetCapture2(TIM2);
TIM_SetCompare2(TIM2, capture + CCR2_Val);
}
if (TIM_GetITStatus(TIM2, TIM_IT_CC3) != RESET)
{
TIM_ClearITPendingBit(TIM2, TIM_IT_CC3);
capture = TIM_GetCapture3(TIM2);
TIM_SetCompare3(TIM2, capture + CCR3_Val);
}
if (TIM_GetITStatus(TIM2, TIM_IT_CC4) != RESET)
{
TIM_ClearITPendingBit(TIM2, TIM_IT_CC4);
capture = TIM_GetCapture4(TIM2);
TIM_SetCompare4(TIM2, capture + CCR4_Val);
}
}
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