通用定时器可以向上计数、向下计数、向上向下双向计数模式。
void TIM_TimeBaseInit(TIM_TypeDef* TIMx,TIM_TimeBaseInitTypeDef* TIM_TimeBaseInitStruct);
typedef struct
{
uint16_t TIM_Prescaler; //预分频系数
uint16_t TIM_CounterMode; //计数模式
uint16_t TIM_Period; //自动装载值
uint16_t TIM_ClockDivision; //不重要
uint8_t TIM_RepetitionCounter; //不重要
} TIM_TimeBaseInitTypeDef;
TIM_TimeBaseStructure.TIM_Period = 4999;
TIM_TimeBaseStructure.TIM_Prescaler =7199;
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
void TIM_Cmd(TIM_TypeDef* TIMx, FunctionalState NewState)
void TIM_ITConfig(TIM_TypeDef* TIMx, uint16_t TIM_IT, FunctionalState NewState);
FlagStatus TIM_GetFlagStatus(TIM_TypeDef* TIMx, uint16_t TIM_FLAG);
void TIM_ClearFlag(TIM_TypeDef* TIMx, uint16_t TIM_FLAG);
ITStatus TIM_GetITStatus(TIM_TypeDef* TIMx, uint16_t TIM_IT);
void TIM_ClearITPendingBit(TIM_TypeDef* TIMx, uint16_t TIM_IT);
RCC_APB1PeriphClockCmd();
TIM_TimeBaseInit();
void TIM_ITConfig(); //使能响应中断
NVIC_Init(); //中断优先级设置
TIM_Cmd(); //使能定时器
TIMx_IRQHandler();
void TIM3_IRQHandler(void) //TIM3中断
{
if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET) //检查TIM3更新中断发生与否,TIM_IT_Update更新中断
{
TIM_ClearITPendingBit(TIM3, TIM_IT_Update ); //清除TIMx更新中断标志
//执行内容
}
}
通过定时器中断配置,每500ms中断一次,然后中断服务函数中控制LED实现LED1状态取反(闪烁)。
Tout(溢出时间)=(ARR+1)(PSC+1)/Tclk
其中(PSC+1)/Tclk相当于周期的时间长度
Tclk为时钟频率(72MHz),系统初始化函数初始化APB1
PSC+1预分频系数加一,设为7199,则定时器的时钟为72M/7200=10k,T=0.1ms
#include "timer.h"
#include "led.h"
//通用定时器3中断初始化
//这里时钟选择为APB1的2倍,而APB1为36M
//arr:自动重装值。
//psc:时钟预分频数
//这里使用的是定时器3!
void TIM3_Int_Init(u16 arr,u16 psc)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //时钟使能
//定时器TIM3初始化
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TIMx时钟频率除数的预分频值
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //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(TIM3, &TIM_TimeBaseStructure); //根据指定的参数初始化TIMx的时间基数单位
TIM_ITConfig(TIM3,TIM_IT_Update,ENABLE ); //使能指定的TIM3中断,允许更新中断
//中断优先级NVIC设置
NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn; //TIM3中断,中断通道
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; //先占优先级0级
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3; //从优先级3级
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能
NVIC_Init(&NVIC_InitStructure); //初始化NVIC寄存器
TIM_Cmd(TIM3, ENABLE); //使能TIMx
}
//定时器3中断服务程序
void TIM3_IRQHandler(void) //TIM3中断
{
if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET) //检查TIM3更新中断发生与否
{
TIM_ClearITPendingBit(TIM3, TIM_IT_Update ); //清除TIMx更新中断标志
LED1=!LED1;
}
}
#include "led.h"
#include "delay.h"
#include "key.h"
#include "sys.h"
#include "usart.h"
#include "timer.h"
int main(void)
{
delay_init(); //延时函数初始化
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); //设置NVIC中断分组2:2位抢占优先级,2位响应优先级
LED_Init(); //LED端口初始化
TIM3_Int_Init(4999,7199);//10Khz的计数频率,计数到5000为500ms
while(1)
{
}
}
PWM模式1:CNT< CCRx时为有效电平
高电平有效就是输出为有效电平时输出高电平
void TIM_OC2PreloadConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPreload);
void TIM_ARRPreloadConfig(TIM_TypeDef* TIMx, FunctionalState NewState);
void TIM_ARRPreloadConfig(TIM_TypeDef* TIMx, FunctionalState NewState);
//简单的说,更改ARR后,ARPE=1,ARR立即生效。。。APRE=0,ARR下个比较周期生效。
void TIM_OCxInit(TIM_TypeDef* TIMx, TIM_OCInitTypeDef* TIM_OCInitStruct);
typedef struct
{
uint16_t TIM_OCMode; //PWM模式1或者模式2
uint16_t TIM_OutputState; //输出使能 OR失能
uint16_t TIM_OutputNState;//没用
uint16_t TIM_Pulse; //比较值,写CCRx
uint16_t TIM_OCPolarity; //比较输出极性
uint16_t TIM_OCNPolarity; //没用
uint16_t TIM_OCIdleState; //没用
uint16_t TIM_OCNIdleState; //没用
} TIM_OCInitTypeDef;
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; //PWM模式2
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //比较输出使能
TIM_OCInitStructure. TIM_Pulse=100; //初始化设置,后面可以不断改变
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //输出极性:TIM输出比较极性高
TIM_OC2Init(TIM3, &TIM_OCInitStructure); //根据T指定的参数初始化外设TIM3 OC2
void TIM_SetCompareX(TIM_TypeDef* TIMx, uint16_t Compare2);
void TIM_OC2PreloadConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPreload);
void TIM_OCxPolarityConfig(TIM_TypeDef* TIMx, uint16_t TIM_OCPolarity);
void TIM_ARRPreloadConfig(TIM_TypeDef* TIMx, FunctionalState NewState);
使用定时器3的PWM功能,输出占空比可变的PWM波,用来驱动LED灯,从而达到LED[PB5]亮度由暗变亮,又从亮变暗,如此循环。
RCC_APB1PeriphClockCmd();
RCC_APB2PeriphClockCmd();
GPIO_Init();
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO,ENABLE);
GPIO_PinRemapConfig(GPIO_PartialRemap_TIM3, ENABLE);
TIM_TimeBaseInit();
TIM_OC2Init();
TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);
TIM_Cmd();
TIM_SetCompare2();
void TIM3_PWM_Init(u16 arr,u16 psc)
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //使能定时器3时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB | 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TIM3 CH2的PWM脉冲波形 GPIOB.5
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5; //TIM_CH2
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //复用推挽输出
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOB, &GPIO_InitStructure);//初始化GPIO
GPIO_PinRemapConfig(GPIO_PartialRemap_TIM3, ENABLE); //Timer3部分重映射 TIM3_CH2->PB5
//初始化TIM3
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TIMx时钟频率除数的预分频值
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(TIM3, &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TIM3 Channel2 PWM模式
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; //选择定时器模式:TIM脉冲宽度调制模式2
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_OC2Init(TIM3, &TIM_OCInitStructure); //根据T指定的参数初始化外设TIM3 OC2
TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable); //使能TIM3在CCR2上的预装载寄存器
TIM_Cmd(TIM3, ENABLE); //使能TIM3
}
TIM3_PWM_Init(899,0); //不分频。PWM频率=72000000/900=80Khz