STM32：用HC-SR04和STM32F103ZET6做超聲波測距
[導(dǎo)讀]最近整理東西，發(fā)現(xiàn)了一個(gè)藍(lán)色的小模塊，上面還有兩個(gè)像喇叭的小東西，關(guān)鍵上面還有絲印，用藍(lán)底白字寫著“HC-SR04”，于是勾起了我的好奇心，動(dòng)動(dòng)小手指，百度找到了這個(gè)小板子的信息，原來是一個(gè)超聲波測距模塊，還挺有意思的，而且只引出來了四個(gè)引腳，應(yīng)用也比較簡單，下面簡單介紹下這個(gè)模塊以及簡單的超聲波測距方案。
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2.要掌握的知識(shí)點(diǎn)和設(shè)備
3.代碼編寫，代碼是參考的正點(diǎn)原子的PWM輸出和輸入捕獲，因?yàn)轫?xiàng)目原理上面說過了，基本就是這兩個(gè)功能的疊加。我本來想用HAL庫來做，但是CUBEMX生成的代碼調(diào)試沒成功，所以最后還是用的原子的標(biāo)準(zhǔn)庫來做的。下面代碼截取的是main.c和time.c。也是這個(gè)項(xiàng)目里面最重要的兩個(gè)部分。
extern u8 TIM5CH1_CAPTURE_STA; //輸入捕獲狀態(tài)extern u16 TIM5CH1_CAPTURE_VAL; //輸入捕獲值int main(void){u32 temp=0;double ss=0;delay_init(); //延時(shí)函數(shù)初始化NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); //設(shè)置NVIC中斷分組2:2位搶占優(yōu)先級(jí)，2位響應(yīng)優(yōu)先級(jí)uart_init(115200); //串口初始化為115200TIM3_PWM_Init(71,199); //不分頻。PWM頻率=72000/(899+1)=80KhzTIM5_Cap_Init(0XFFFF,72-1); //以1Mhz的頻率計(jì)數(shù)while(1){delay_ms(10);// TIM_SetCompare2(TIM3,TIM_GetCapture2(TIM3)+1);TIM_SetCompare2(TIM3,63);if(TIM_GetCapture2(TIM3)==300)TIM_SetCompare2(TIM3,0);if(TIM5CH1_CAPTURE_STA&0X80)//成功捕獲到了一次上升沿{temp=TIM5CH1_CAPTURE_STA&0X3F;temp*=65536;//溢出時(shí)間總和temp+=TIM5CH1_CAPTURE_VAL;//得到總的高電平時(shí)間ss=temp*340/2/1000;printf("高電平時(shí)間:%d us\r\n",temp);//打印總的高點(diǎn)平時(shí)間printf("測試距離為:%3.0f mm\r\n",ss);TIM5CH1_CAPTURE_STA=0;//開啟下一次捕獲delay_ms(500);}}}
void TIM3_Int_Init(u16 arr,u16 psc){TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;NVIC_InitTypeDef NVIC_InitStructure;RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //時(shí)鐘使能TIM_TimeBaseStructure.TIM_Period = arr; //設(shè)置在下一個(gè)更新事件裝入活動(dòng)的自動(dòng)重裝載寄存器周期的值 計(jì)數(shù)到5000為500msTIM_TimeBaseStructure.TIM_Prescaler =psc; //設(shè)置用來作為TIMx時(shí)鐘頻率除數(shù)的預(yù)分頻值 10Khz的計(jì)數(shù)頻率TIM_TimeBaseStructure.TIM_ClockDivision = 0; //設(shè)置時(shí)鐘分割:TDTS = Tck_timTIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上計(jì)數(shù)模式TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); //根據(jù)TIM_TimeBaseInitStruct中指定的參數(shù)初始化TIMx的時(shí)間基數(shù)單位TIM_ITConfig( //使能或者失能指定的TIM中斷TIM3, //TIM2TIM_IT_Update | //TIM 中斷源TIM_IT_Trigger, //TIM 觸發(fā)中斷源ENABLE //使能);NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn; //TIM3中斷NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; //先占優(yōu)先級(jí)0級(jí)NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3; //從優(yōu)先級(jí)3級(jí)NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能NVIC_Init(&NVIC_InitStructure); //根據(jù)NVIC_InitStruct中指定的參數(shù)初始化外設(shè)NVIC寄存器TIM_Cmd(TIM3, ENABLE); //使能TIMx外設(shè)}void TIM3_IRQHandler(void) //TIM3中斷{if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET) //檢查指定的TIM中斷發(fā)生與否:TIM 中斷源{TIM_ClearITPendingBit(TIM3, TIM_IT_Update ); //清除TIMx的中斷待處理位:TIM 中斷源LED1=!LED1;}}//PWM輸出初始化//arr：自動(dòng)重裝值//psc：時(shí)鐘預(yù)分頻數(shù)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);RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB | RCC_APB2Periph_AFIO, ENABLE); //使能GPIO外設(shè)和AFIO復(fù)用功能模塊時(shí)鐘使能GPIO_PinRemapConfig(GPIO_PartialRemap_TIM3, ENABLE); //Timer3部分重映射 TIM3_CH2->PB5 //用于TIM3的CH2輸出的PWM通過該LED顯示//設(shè)置該引腳為復(fù)用輸出功能,輸出TIM3 CH2的PWM脈沖波形GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5; //TIM_CH2GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //復(fù)用推挽輸出GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_Init(GPIOB, &GPIO_InitStructure);//GPIO_WriteBit(GPIOA, GPIO_Pin_7,Bit_SET); // PA7上拉TIM_TimeBaseStructure.TIM_Period = arr; //設(shè)置在下一個(gè)更新事件裝入活動(dòng)的自動(dòng)重裝載寄存器周期的值 80KTIM_TimeBaseStructure.TIM_Prescaler =psc; //設(shè)置用來作為TIMx時(shí)鐘頻率除數(shù)的預(yù)分頻值 不分頻TIM_TimeBaseStructure.TIM_ClockDivision = 0; //設(shè)置時(shí)鐘分割:TDTS = Tck_timTIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上計(jì)數(shù)模式TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); //根據(jù)TIM_TimeBaseInitStruct中指定的參數(shù)初始化TIMx的時(shí)間基數(shù)單位TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; //選擇定時(shí)器模式:TIM脈沖寬度調(diào)制模式2TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //比較輸出使能TIM_OCInitStructure.TIM_Pulse = 0; //設(shè)置待裝入捕獲比較寄存器的脈沖值TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //輸出極性:TIM輸出比較極性高TIM_OC2Init(TIM3, &TIM_OCInitStructure); //根據(jù)TIM_OCInitStruct中指定的參數(shù)初始化外設(shè)TIMxTIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable); //使能TIMx在CCR2上的預(yù)裝載寄存器TIM_ARRPreloadConfig(TIM3, ENABLE); //使能TIMx在ARR上的預(yù)裝載寄存器TIM_Cmd(TIM3, ENABLE); //使能TIMx外設(shè)}//定時(shí)器5通道1輸入捕獲配置TIM_ICInitTypeDef TIM5_ICInitStructure;void TIM5_Cap_Init(u16 arr,u16 psc){GPIO_InitTypeDef GPIO_InitStructure;TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;NVIC_InitTypeDef NVIC_InitStructure;RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM5, ENABLE); //使能TIM5時(shí)鐘RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE); //使能GPIOA時(shí)鐘GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0; //PA0 清除之前設(shè)置GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD; //PA0 輸入GPIO_Init(GPIOA, &GPIO_InitStructure);GPIO_ResetBits(GPIOA,GPIO_Pin_0); //PA0 下拉//初始化定時(shí)器5 TIM5TIM_TimeBaseStructure.TIM_Period = arr; //設(shè)定計(jì)數(shù)器自動(dòng)重裝值TIM_TimeBaseStructure.TIM_Prescaler =psc; //預(yù)分頻器TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //設(shè)置時(shí)鐘分割:TDTS = Tck_timTIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上計(jì)數(shù)模式TIM_TimeBaseInit(TIM5, &TIM_TimeBaseStructure); //根據(jù)TIM_TimeBaseInitStruct中指定的參數(shù)初始化TIMx的時(shí)間基數(shù)單位//初始化TIM5輸入捕獲參數(shù)TIM5_ICInitStructure.TIM_Channel = TIM_Channel_1; //CC1S=01 選擇輸入端 IC1映射到TI1上TIM5_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; //上升沿捕獲TIM5_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; //映射到TI1上TIM5_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; //配置輸入分頻,不分頻TIM5_ICInitStructure.TIM_ICFilter = 0x00;//IC1F=0000 配置輸入濾波器 不濾波TIM_ICInit(TIM5, &TIM5_ICInitStructure);//中斷分組初始化NVIC_InitStructure.NVIC_IRQChannel = TIM5_IRQn; //TIM3中斷NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2; //先占優(yōu)先級(jí)2級(jí)NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //從優(yōu)先級(jí)0級(jí)NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能NVIC_Init(&NVIC_InitStructure); //根據(jù)NVIC_InitStruct中指定的參數(shù)初始化外設(shè)NVIC寄存器TIM_ITConfig(TIM5,TIM_IT_Update|TIM_IT_CC1,ENABLE);//允許更新中斷 ,允許CC1IE捕獲中斷TIM_Cmd(TIM5,ENABLE ); //使能定時(shí)器5}u8 TIM5CH1_CAPTURE_STA=0; //輸入捕獲狀態(tài)u16 TIM5CH1_CAPTURE_VAL; //輸入捕獲值//定時(shí)器5中斷服務(wù)程序void TIM5_IRQHandler(void){if((TIM5CH1_CAPTURE_STA&0X80)==0)//還未成功捕獲{if (TIM_GetITStatus(TIM5, TIM_IT_Update) != RESET){if(TIM5CH1_CAPTURE_STA&0X40)//已經(jīng)捕獲到高電平了{if((TIM5CH1_CAPTURE_STA&0X3F)==0X3F)//高電平太長了{TIM5CH1_CAPTURE_STA|=0X80;//標(biāo)記成功捕獲了一次TIM5CH1_CAPTURE_VAL=0XFFFF;}else TIM5CH1_CAPTURE_STA++;}}if (TIM_GetITStatus(TIM5, TIM_IT_CC1) != RESET)//捕獲1發(fā)生捕獲事件{if(TIM5CH1_CAPTURE_STA&0X40) //捕獲到一個(gè)下降沿{TIM5CH1_CAPTURE_STA|=0X80; //標(biāo)記成功捕獲到一次高電平脈寬TIM5CH1_CAPTURE_VAL=TIM_GetCapture1(TIM5);TIM_OC1PolarityConfig(TIM5,TIM_ICPolarity_Rising); //CC1P=0 設(shè)置為上升沿捕獲}else //還未開始,第一次捕獲上升沿{TIM5CH1_CAPTURE_STA=0; //清空TIM5CH1_CAPTURE_VAL=0;TIM_SetCounter(TIM5,0);TIM5CH1_CAPTURE_STA|=0X40; //標(biāo)記捕獲到了上升沿TIM_OC1PolarityConfig(TIM5,TIM_ICPolarity_Falling); //CC1P=1 設(shè)置為下降沿捕獲}}}TIM_ClearITPendingBit(TIM5, TIM_IT_CC1|TIM_IT_Update); //清除中斷標(biāo)志位}
4.2串口顯示結(jié)果
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PS:附件是我在網(wǎng)上找的一個(gè)HC-SR04模塊的資料，可以參考，但我看了下好像和我手上這個(gè)有點(diǎn)兒不一樣，但引腳定義是一樣的，不影響整體設(shè)計(jì)思路，可以看看。
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