超音波測距

蜂鳴器(Buzzer)是產生聲音的信號裝置，有機械型、機電型及壓電型。蜂鳴器的典型應用包括警笛、報警裝置、火災警報器、防空警報器、防盜器、定時器等。<參考維基百科>
本次使用的小型蜂鳴器都是電磁式蜂鳴器，主要依靠電流與磁鐵間的推斥或吸引來產生振動，發出聲音。 此類蜂鳴器一般分為自帶震盪源(自激式)或不帶震盪源(他激式)兩種。自激式的蜂鳴器時直接使用直流電即可發出固定聲音頻率；而他激式的蜂鳴器則需要提供聲音訊號才能發聲。
要能夠發出不同頻率的聲音，則必須注意選用他激式，選用時仍需要注意蜂鳴器上的工電壓。

配合以下測距程式使用之電路                                                                                                                                                超音波電路加上簡易直接輸出蜂鳴器電路

const int trigPin = 5;

const int echoPin = 18;

//define sound speed in cm/uS

#define SOUND_SPEED 0.034

#define CM_TO_INCH 0.393701

long duration;

float distanceCm;

float distanceInch;

void setup() {

  Serial.begin(115200); // Starts the serial communication

  pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output

  pinMode(echoPin, INPUT); // Sets the echoPin as an Input

}

void loop() {

  // Clears the trigPin

  digitalWrite(trigPin, LOW);

  delayMicroseconds(2);

  // Sets the trigPin on HIGH state for 10 micro seconds

  digitalWrite(trigPin, HIGH);

  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  // Reads the echoPin, returns the sound wave travel time in microseconds

  duration = pulseIn(echoPin, HIGH);

  // Calculate the distance

  distanceCm = duration * SOUND_SPEED/2;

  // Convert to inches

  distanceInch = distanceCm * CM_TO_INCH;

  // Prints the distance in the Serial Monitor

  Serial.print("Distance (cm): ");

  Serial.println(distanceCm);

  Serial.print("Distance (inch): ");

  Serial.println(distanceInch);

  delay(1000);

}

#include <ESP32Servo.h>

int trigPin = 5;    // 超音波感測器 Trig腳接 ESP32 pin 05

int echoPin = 18;    //超音波感測器 Echo 腳接 ESP32 pin 18

int speakerpin = 17;  //蜂鳴器 + 腳接 ESP32 pin 7

long duration, distanceCm ;  //宣告計算距離時，需要用到的兩個實數

void setup() {

  Serial.begin (115200);           //設定序列埠監控視窗 (Serial Monitor) 和 ESP32資料傳輸速率為 15200 bps (Bits Per Second)

  pinMode(trigPin, OUTPUT);      //ESP32 對外啟動距離感測器Trig腳，射出超音波 

  pinMode(echoPin, INPUT);       //超音波被障礙物反射後，Arduino讀取感測器Echo腳的時間差

  pinMode(speakerpin, OUTPUT);   //ESP32對蜂鳴器送出電壓，使其鳴叫

}

void loop()

{                                  //程式計算出距離值 cm

  digitalWrite(trigPin, LOW);

  delayMicroseconds(5);

  digitalWrite(trigPin, HIGH);

  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  pinMode(echoPin, INPUT);

  duration = pulseIn(echoPin, HIGH);

  distanceCm = (duration/2) / 29.1;  

  Serial.print(distanceCm );     //印出距離值 cm 在序列埠監控顯示器 單位公分

  Serial.println(" cm");

   if (distanceCm <= 5) {                       //距離小於5公分，蜂鳴器一直叫 

    tone(speakerpin,1000); //輸出1000Hz 音調

    delay (20);

      }

  if (distanceCm > 5 && distanceCm <= 15) {             //距離介於5到15公分，蜂鳴器斷斷續續叫，每次0.1秒 

    tone(speakerpin,1000); //輸出1000Hz 音調

    delay (100);

    noTone(speakerpin); //靜音

    delay (100);

   }

  if (distanceCm > 15 && distanceCm <= 30 ){                        // 距離介於15到30公分，蜂鳴器斷斷續續叫，每次0.5秒 

    tone(speakerpin,1000); //輸出1000Hz 音調。  

    delay (500);

    noTone(speakerpin); //靜音

    delay (500);

      }

  delay(10); 

  }

利用 之前的七段顯示器電路與超音波測距電路顯示

要求如下

1. 99~90cm >顯示> 9 

2. 89~80cm >顯示> 8

3. 79~70cm >顯示> 7 

4. 69~60cm >顯示> 6 

5. 59~50cm >顯示> 5 

6. 49~40cm >顯示> 4 

7. 39~30cm >顯示> 3 

8. 29~20cm >顯示> 2 

9. 19~10cm >顯示> 1 

10. 10以下      >顯示> 0 

const int trigPin = 5;
const int echoPin = 18;

//define sound speed in cm/uS
#define SOUND_SPEED 0.034
#define CM_TO_INCH 0.393701

int cm;

long duration;

float distanceCm;

float distanceInch;

//------------------------------

//             p, g, f, e, d, c, b, a    七段顯示函數

char segpin[]={27,32,33,13,04,14,26,25};

//                                 p,g,f,e,d,c,b,a  共陽極

byte seven_seg_digits[][8] = {   { 1,1,0,0,0,0,0,0 },  // = 0

                                 { 1,1,1,1,1,0,0,1 },  // = 1

                                 { 1,0,1,0,0,1,0,0 },  // = 2

                                 { 1,0,1,1,0,0,0,0 },  // = 3

                                 { 1,0,0,1,1,0,0,1 },  // = 4

                                 { 1,0,0,1,0,0,1,0 },  // = 5

                                 { 1,0,0,0,0,0,1,1 },  // = 6

                                 { 1,1,1,1,1,0,0,0 },  // = 7

                                 { 1,0,0,0,0,0,0,0 },  // = 8

                                 { 1,0,0,1,1,0,0,0 }   // = 9

                             };

// 在七段顯示器上顯示指定的一個數字 

void sevenSegWrite(byte digit) {

  for (byte seg = 0; seg <8; ++seg) 

    digitalWrite(segpin[seg], seven_seg_digits[digit][seg]);// 共陽極 //    digitalWrite(segpin[seg], !seven_seg_digits[digit][seg]);// 共陰極

}

//--------------------------------

void setup() {

  Serial.begin(115200); // Starts the serial communication

  pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output

  pinMode(echoPin, INPUT); // Sets the echoPin as an Input

  //------------------------------------------

  for(int i=0;i<8;i++){

    pinMode(segpin[i], OUTPUT);

    digitalWrite(segpin[i], 0);

    }

  delay(2000);

  //------------------------------------------------

}

void loop() {

  // Clears the trigPin

  digitalWrite(trigPin, LOW);

  delayMicroseconds(2);

  // Sets the trigPin on HIGH state for 10 micro seconds

  digitalWrite(trigPin, HIGH);

  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  // Reads the echoPin, returns the sound wave travel time in microseconds

  duration = pulseIn(echoPin, HIGH);

  // Calculate the distance

  distanceCm = duration * SOUND_SPEED/2;

  // Convert to inches

  distanceInch = distanceCm * CM_TO_INCH;

  // Prints the distance in the Serial Monitor

  Serial.print("Distance (cm): ");

  Serial.println(distanceCm);

  Serial.print("Distance (inch): ");

  Serial.println(distanceInch);

  //---------------------------------

  cm=distanceCm/10;

   sevenSegWrite(cm);

  //-----------------------------------

  delay(1000);

}

#include <Wire.h> 

#include <LiquidCrystal_I2C.h>

// Set the LCD address to 0x27 for a 16 chars and 2 line display

LiquidCrystal_I2C lcd(0x27, 16, 2);

const int trigPin = 5;

const int echoPin = 18;

//define sound speed in cm/uS

#define SOUND_SPEED 0.034

#define CM_TO_INCH 0.393701

long duration;

float distanceCm;

float distanceInch;

void setup() {

  Serial.begin(115200); // Starts the serial communication

  pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output

  pinMode(echoPin, INPUT); // Sets the echoPin as an Input

  lcd.begin();

  // Turn on the blacklight and print a message.

  lcd.backlight();

}

void loop() {

  // Clears the trigPin

  digitalWrite(trigPin, LOW);

  delayMicroseconds(2);

  // Sets the trigPin on HIGH state for 10 micro seconds

  digitalWrite(trigPin, HIGH);

  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  // Reads the echoPin, returns the sound wave travel time in microseconds

  duration = pulseIn(echoPin, HIGH);

  // Calculate the distance

  distanceCm = duration * SOUND_SPEED/2;

  // Convert to inches

  distanceInch = distanceCm * CM_TO_INCH;

  // Prints the distance in the Serial Monitor

  Serial.print("Distance (cm): ");

  Serial.println(distanceCm);

  Serial.print("Distance (inch): ");

  Serial.println(distanceInch);

  lcd.setCursor(0,0);//設定游標

  lcd.print("CM=");

  lcd.setCursor(3,0);//設定游標

  lcd.print(distanceCm);

  delay(1000);

}