请教一下,我按照定时器输入捕获实验将TIM5的通道1改为TIM4的通道1,2均能正确测得脉冲高电平时长,
但是改为TIM4的通道3或4时,出错,具体的:
改为通道3,代码如下:
//定时器4通道3输入捕获配置
TIM_ICInitTypeDef TIM4_ICInitStructure;
void TIM4_Cap_Init(u16 arr,u16 psc)
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE); //使能TIM4时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE); //使能GPIOB时钟
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8; //PB8 清除之前设置
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD; //PB8 输入
GPIO_Init(GPIOB, &GPIO_InitStructure);
GPIO_ResetBits(GPIOB,GPIO_Pin_8); //PB8 下拉
//初始化定时器4 TIM4
TIM_TimeBaseStructure.TIM_Period = arr; //设定计数器自动重装值
TIM_TimeBaseStructure.TIM_Prescaler =psc; //预分频器
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(TIM4, &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TIM4输入捕获参数
TIM4_ICInitStructure.TIM_Channel = TIM_Channel_3; //CC1S=01 选择输入端 IC1映射到TI3上
TIM4_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; //上升沿捕获
TIM4_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; //映射到TI1上
TIM4_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; //配置输入分频,不分频
TIM4_ICInitStructure.TIM_ICFilter = 0x00;//IC1F=0000 配置输入滤波器 不滤波
TIM_ICInit(TIM4, &TIM4_ICInitStructure);
//中断分组初始化
NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn; //TIM4中断
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2; //先占优先级2级
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //从优先级0级
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能
NVIC_Init(&NVIC_InitStructure); //根据NVIC_InitStruct中指定的参数初始化外设NVIC寄存器
TIM_ITConfig(TIM4,TIM_IT_Update|TIM_IT_CC3,ENABLE);//允许更新中断 ,允许CC3IE捕获中断
TIM_Cmd(TIM4,ENABLE ); //使能定时器4
}
u8 TIM4CH3_CAPTURE_STA=0; //输入捕获状态
u16 TIM4CH3_CAPTURE_VAL; //输入捕获值
//定时器4中断服务程序
void TIM4_IRQHandler(void)
{
if((TIM4CH3_CAPTURE_STA&0X80)==0)//还未成功捕获
{
if (TIM_GetITStatus(TIM4, TIM_IT_Update) != RESET)
{
if(TIM4CH3_CAPTURE_STA&0X40)//已经捕获到高电平了
{
if((TIM4CH3_CAPTURE_STA&0X3F)==0X3F)//高电平太长了
{
TIM4CH3_CAPTURE_STA|=0X80;//标记成功捕获了一次
TIM4CH3_CAPTURE_VAL=0XFFFF;
}else TIM4CH3_CAPTURE_STA++;
}
}
if (TIM_GetITStatus(TIM4, TIM_IT_CC3) != RESET)//捕获3发生捕获事件
{
if(TIM4CH3_CAPTURE_STA&0X40) //捕获到一个下降沿
{
TIM4CH3_CAPTURE_STA|=0X80; //标记成功捕获到一次上升沿
TIM4CH3_CAPTURE_VAL=TIM_GetCapture3(TIM4);
TIM_OC3PolarityConfig(TIM4,TIM_ICPolarity_Rising); //CC3P=0 设置为上升沿捕获
}else //还未开始,第一次捕获上升沿
{
TIM4CH3_CAPTURE_STA=0; //清空
TIM4CH3_CAPTURE_VAL=0;
TIM_SetCounter(TIM4,0);
TIM4CH3_CAPTURE_STA|=0X40; //标记捕获到了上升沿
TIM_OC3PolarityConfig(TIM4,TIM_ICPolarity_Falling); //CC1P=1 设置为下降沿捕获
}
}
}
TIM_ClearITPendingBit(TIM4, TIM_IT_CC3|TIM_IT_Update); //清除中断标志位
}
出错现象:每次给TIM4的通道3(PB8)输入脉冲,战舰板就会蜂鸣器报警,且串口没有高电平时长输出
改为TIM4的通道4,代码如下:
//定时器4通道4输入捕获配置
TIM_ICInitTypeDef TIM4_ICInitStructure;
void TIM4_Cap_Init(u16 arr,u16 psc)
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE); //使能TIM4时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE); //使能GPIOB时钟
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9; //PB9 清除之前设置
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD; //PB9 输入
GPIO_Init(GPIOB, &GPIO_InitStructure);
GPIO_ResetBits(GPIOB,GPIO_Pin_9); //PB9 下拉
//初始化定时器4 TIM4
TIM_TimeBaseStructure.TIM_Period = arr; //设定计数器自动重装值
TIM_TimeBaseStructure.TIM_Prescaler =psc; //预分频器
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(TIM4, &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TIM4输入捕获参数
TIM4_ICInitStructure.TIM_Channel = TIM_Channel_4; //CC1S=01 选择输入端 IC1映射到TI4上
TIM4_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; //上升沿捕获
TIM4_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; //映射到TI1上
TIM4_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; //配置输入分频,不分频
TIM4_ICInitStructure.TIM_ICFilter = 0x00;//IC1F=0000 配置输入滤波器 不滤波
TIM_ICInit(TIM4, &TIM4_ICInitStructure);
//中断分组初始化
NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn; //TIM4中断
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2; //先占优先级2级
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //从优先级0级
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能
NVIC_Init(&NVIC_InitStructure); //根据NVIC_InitStruct中指定的参数初始化外设NVIC寄存器
TIM_ITConfig(TIM4,TIM_IT_Update|TIM_IT_CC4,ENABLE);//允许更新中断 ,允许CC4IE捕获中断
TIM_Cmd(TIM4,ENABLE ); //使能定时器4
}
u8 TIM4CH4_CAPTURE_STA=0; //输入捕获状态
u16 TIM4CH4_CAPTURE_VAL; //输入捕获值
//定时器4中断服务程序
void TIM4_IRQHandler(void)
{
if((TIM4CH4_CAPTURE_STA&0X80)==0)//还未成功捕获
{
if (TIM_GetITStatus(TIM4, TIM_IT_Update) != RESET)
{
if(TIM4CH4_CAPTURE_STA&0X40)//已经捕获到高电平了
{
if((TIM4CH4_CAPTURE_STA&0X3F)==0X3F)//高电平太长了
{
TIM4CH4_CAPTURE_STA|=0X80;//标记成功捕获了一次
TIM4CH4_CAPTURE_VAL=0XFFFF;
}else TIM4CH4_CAPTURE_STA++;
}
}
if (TIM_GetITStatus(TIM4, TIM_IT_CC4) != RESET)//捕获4发生捕获事件
{
if(TIM4CH4_CAPTURE_STA&0X40) //捕获到一个下降沿
{
TIM4CH4_CAPTURE_STA|=0X80; //标记成功捕获到一次上升沿
TIM4CH4_CAPTURE_VAL=TIM_GetCapture4(TIM4);
TIM_OC4PolarityConfig(TIM4,TIM_ICPolarity_Rising); //CC4P=0 设置为上升沿捕获
}else //还未开始,第一次捕获上升沿
{
TIM4CH4_CAPTURE_STA=0; //清空
TIM4CH4_CAPTURE_VAL=0;
TIM_SetCounter(TIM4,0);
TIM4CH4_CAPTURE_STA|=0X40; //标记捕获到了上升沿
TIM_OC4PolarityConfig(TIM4,TIM_ICPolarity_Falling); //CC4P=1 设置为下降沿捕获
}
}
}
TIM_ClearITPendingBit(TIM4, TIM_IT_CC4|TIM_IT_Update); //清除中断标志位
}
出错现象:此时虽然串口有输出时长信息,但是观察发现,这个时长在脉冲上升沿输入时就输出了,根本不是上升沿和下降沿直接的高电平的时长!
请教高位高手,这是什么原因?
还有,根据《STM32中文参考手册_V10》p110的表19,定时器TIM2/3/4/5_CHx输入捕获通道对应的GPIO应当设置为“浮空输入”,
请教一下原子哥,为什么你的程序中要把IO口设置为下拉输入?
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