Chapter 19 Ultrasonic Ranging

In this chapter, we learn a module which use ultrasonic to measure distance, HC-SR04.

Project 19.1 Ultrasonic Ranging

In this project, we use ultrasonic ranging module to measure distance, and print out the data in the terminal.

Component List

  • ESP32-S3-WROOM x1

  • GPIO Extension Board x1

  • 830 Tie-Points Breadboard x1

  • Ultrasonic Sensor x1

  • F-M DuPont Cable x4

Connect

Note that the voltage of ultrasonic module is 5V in the circuit.

../_images/19.png

Sketch

Sketch_19.1_Ultrasonic_Ranging

../_images/19.1.png

Download the code to ESP32-S3 WROOM, open the serial port monitor, set the baud rate to 115200 and you can use it to measure the distance between the ultrasonic module and the object. As shown in the following figure:

../_images/19.11.png

Code

The following is the program code:

#define trigPin 13 // define TrigPin
#define echoPin 14 // define EchoPin.
#define MAX_DISTANCE 700 // Maximum sensor distance is rated at 400-500cm.
//timeOut= 2*MAX_DISTANCE /100 /340 *1000000 = MAX_DISTANCE*58.8
float timeOut = MAX_DISTANCE * 60;
int soundVelocity = 340; // define sound speed=340m/s

void setup() {
pinMode(trigPin,OUTPUT);// set trigPin to output mode
pinMode(echoPin,INPUT); // set echoPin to input mode
Serial.begin(115200);   // Open serial monitor at 115200 baud to see ping results.
}

void loop() {
delay(100); // Wait 100ms between pings (about 20 pings/sec).
Serial.printf("Distance: ");
Serial.print(getSonar()); // Send ping, get distance in cm and print result
Serial.println("cm");
}

float getSonar() {
unsigned long pingTime;
float distance;
// make trigPin output high level lasting for 10μs to triger HC_SR04
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
// Wait HC-SR04 returning to the high level and measure out this waitting time
pingTime = pulseIn(echoPin, HIGH, timeOut);
// calculate the distance according to the time
distance = (float)pingTime * soundVelocity / 2 / 10000;
return distance; // return the distance value
}

Project 19.2 Ultrasonic Ranging

Component List and Connect

Component List and Connect are the same as the previous section

Sketch

How to install the library

We use the third party library UltrasonicSensor. If you haven’t installed it yet, please do so before learning. The steps to add third-party Libraries are as follow s: open arduino->Sketch->Include library-> Manage libraries. Enter “UltrasonicSensor” in the search bar and select “UltrasonicSensor” for installation. Refer to the following operations:

../_images/19.2_lib.png

Sketch_19.2_Ultrasonic_Ranging

../_images/19.2.png

Download the code to ESP32-S3 WROOM, open the serial port monitor, set the baud rate to 115200. Use the ultrasonic module to measure distance. As shown in the following figure:

../_images/19.21.png

Code

The following is the program code:

#include <UltrasonicSensor.h>

UltrasonicSensor ultrasonic(13, 14);  // Create ultrasonic sensor object, using pins 13 and 14

void setup() {
Serial.begin(115200);  // Initialize serial communication at 115200 baud

int temperature = 22;  // Set ambient temperature (in Celsius)
ultrasonic.setTemperature(temperature);  // Calibrate sensor for the set temperature
}

void loop() {
int distance = ultrasonic.distanceInCentimeters();  // Measure distance in centimeters
Serial.printf("Distance: %dcm\n",distance);  // Print the measured distance
delay(300);  // Wait for 300 milliseconds before next measurement
}