Freenove ESP32 User Manual (English)

To Next Page

To Previous Page

Need support?  support@freenove.com

110

Chapter 10 Ultrasonic Ranging

www.freenove.com █

UltrasonicRanging.cpp

#include "UltrasonicRanging.h"

constexpr int MAX_DISTANCE = 300; // Maximum sensor distance is rated at 400-500cm.

constexpr float timeOut = MAX_DISTANCE * 60; // timeOut= 2*MAX_DISTANCE /100 /340 *1000000 =

MAX_DISTANCE*58.8

constexpr int soundVelocity = 340; // define sound speed=340m/s

void setupSonar() {

pinMode(PIN_TRIG, OUTPUT); // set trigPin to output mode

pinMode(PIN_ECHO, INPUT); // set echoPin to input mode

}

float getSonar() {

unsigned long pingTime, t0, t1;

float distance;

// make PIN_TRIG output high level lasting for 10μs to triger HC_SR04

digitalWrite(PIN_TRIG, HIGH);

delayMicroseconds(10);

digitalWrite(PIN_TRIG, LOW);

// Wait HC-SR04 returning to the high level and measure out this waitting time

t0 = micros();

pingTime = pulseIn(PIN_ECHO, HIGH, timeOut); // unit: us

t1 = micros() - t0;

// calculate the distance according to the time

if (t1 < timeOut) {

distance = (float)pingTime * soundVelocity / 2 / 10000;

} else {

distance = MAX_DISTANCE;

}

return distance; // return the distance value

}

Ultrasonic module initialization function.

void setupSonar() {

pinMode(PIN_TRIG, OUTPUT); // set trigPin to output mode

pinMode(PIN_ECHO, INPUT); // set echoPin to input mode

}

Need help?

Do you have a question about the Freenove ESP32 and is the answer not in the manual?

Freenove ESP32 Specifications

General

Clock Speed	240 MHz
RAM	520 KB SRAM
Wi-Fi	802.11 b/g/n
UART	3
Operating Voltage	3.3V
Input Voltage	5V
DC Current per I/O Pin	40mA
USB	Micro USB
Microcontroller	ESP32
Chip	ESP32
Bluetooth	Bluetooth v4.2 BR/EDR and BLE standard
ADC Channels/Analog Input Pins	18
I2C	Yes
SPI	Yes
Interfaces	I2C, SPI, UART
CPU	Dual-Core 32-bit LX6 Microprocessor