本帖最后由 北极星405 于 2016-4-19 20:55 编辑
定时器的捕获让我用的非常困惑，到现在没弄太明白…………主要功能很简单就是超声波测距，只是这个用于鱼缸补水的，是测量液面的，对测得距离要运算一下，如下图
主要代码：
printf重定向：
- int fputc(int ch, FILE *f)
- {
- /* Place your implementation of fputc here */
- USART_DataSend( USART1, (uint8_t) ch );
- /* Loop until transmit data register is empty */
- while (USART_GetBitState ( USART1 , USART_FLAG_TC ) == RESET);
- return ch;
- }
中断配置和中断函数：
- void NVIC_ConfigurationTIMER(void)
- {
- NVIC_InitPara NVIC_InitStructure;
- NVIC_PRIGroup_Enable(NVIC_PRIGROUP_1);
- /* Enable the TIMER3 Interrupt */
- NVIC_InitStructure.NVIC_IRQ = TIMER3_IRQn;
- NVIC_InitStructure.NVIC_IRQPreemptPriority = 0;
- NVIC_InitStructure.NVIC_IRQSubPriority = 1;
- NVIC_InitStructure.NVIC_IRQEnable = ENABLE;
- NVIC_Init(&NVIC_InitStructure);
- }
- void TIM3_Configuration(void)
- {
- /* TIMER3 configuration: Input Capture mode -------------------
- The external signal is connected to TIMER1 CH1 pin(PE9)
- The Rising edge is used as active edge
- The TIMER1 CHCC1 is used to compute the frequency value
- ------------------------------------------------------------ */
- TIMER_BaseInitPara TIM_TimeBaseStructure;
-
- /* TIMER1 clock enable */
- RCC_APB1PeriphClock_Enable(RCC_APB1PERIPH_TIMER3,ENABLE); //ÎÊÌ⾹Ȼ³öÔÚÕâÀ
- //APB2µÄÍâÉèµ÷ÓÃÁËAPB1µÄÅäÖú¯Êý£¡
- //RCC_APB2PeriphClock_Enable
- /* TIMER3 configuration */
- TIMER_DeInit(TIMER3);
- TIM_TimeBaseStructure.TIMER_Prescaler = 71;
- TIM_TimeBaseStructure.TIMER_CounterMode = TIMER_COUNTER_UP;
- TIM_TimeBaseStructure.TIMER_Period = 60000;
- TIM_TimeBaseStructure.TIMER_ClockDivision = TIMER_CDIV_DIV1;
- TIMER_BaseInit(TIMER3,&TIM_TimeBaseStructure);
- /* Input capture configuration */
- TIM_ICInitStructure.TIMER_CH = TIMER_CH_1;
- TIM_ICInitStructure.TIMER_ICPolarity = TIMER_IC_POLARITY_BOTH_EDGE; //TIMER_IC_POLARITY_RISING
- TIM_ICInitStructure.TIMER_ICSelection = TIMER_IC_SELECTION_DIRECTTI;
- TIM_ICInitStructure.TIMER_ICPrescaler = TIMER_IC_PSC_DIV1;
- TIM_ICInitStructure.TIMER_ICFilter = 0x0;
- TIMER_ICInit(TIMER3, &TIM_ICInitStructure);
- /* Auto-reload preload enable */
- TIMER_CARLPreloadConfig(TIMER3,ENABLE);
- /* Clear the CH1 Interrupt flag an Enable the CH1 Interrupt Request */
- TIMER_ClearIntBitState(TIMER3,TIMER_INT_CH1);
- TIMER_INTConfig(TIMER3,TIMER_INT_CH1,ENABLE);
-
- /* TIMER enable counter*/
- TIMER_Enable( TIMER3, ENABLE );
- printf("TIMER Init Finish!\r\n");
- }
- /**
- * [url=home.php?mod=space&uid=247401]@brief[/url] This function handles TIMER3 interrupt request.
- * @param None
- * @retval None
- */
- void TIMER3_IRQHandler(void)
- {
- __IO uint8_t PINSTATE=GPIO_ReadInputBit(GPIOA,GPIO_PIN_4);
- if(TIMER_GetIntBitState(TIMER3,TIMER_INT_CH1)==ENABLE)
- {
-
- TIMER_ClearIntBitState(TIMER3,TIMER_INT_CH1);
- if(GPIO_ReadInputBit(GPIOA,GPIO_PIN_4)!=0)
- {
- readvalue1 = TIMER_GetCapture1(TIMER3);
- // printf("readvalue1:%d\r\n",readvalue1);
- }
- else if(GPIO_ReadInputBit(GPIOA,GPIO_PIN_4)==0)
- {
- readvalue2 = TIMER_GetCapture1(TIMER3);
- if (readvalue2 > readvalue1)
- {
- count = (readvalue2 - readvalue1);
- }
- else
- {
- count = ((60000 - readvalue1) + readvalue2);
- }
- count =count-550; //这里有很大疑问！不减去550距离一直就多100mm，不知道哪里问题了……
- distance =195-count*17/100;
- // printf("the value1 is %d,the value2 is %d,%dmm\r\n",readvalue1,readvalue2,count*17/100);
- printf("µ±Ç°Ë®Î» %d mm\r\n\r\n",distance);
- }
- else
- ;
- }
- }
用的定时器3 CH1,Echo接PC6,Trig接PA4
试验：
结果：
手边没有直尺，就找了个小米充电宝对比下，小米是92mm左右高度，这个页面略低于充电宝，测量结果86mm，还可以的
还有一个很大的疑问就是为什么读出来的数据有一个550左右的偏差，如上面代码中：
“count =count-550; //这里有很大疑问！不减去550距离一直就多100mm，不知道哪里问题了……”
还请高人指点！
具体代码如下：
C文件.rar
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