• sales

    +86-0755-88291180

HC-SR04 User Guide

Arduino connects ultrasonic sensor for distance measurement 

Ultrasonic sensors are suitable for static distance measurement of large flat surfaces. The range of ordinary ultrasonic sensors is about 2cm-450cm, and the resolution is 3mm (the test environment is not so good, and the personal measurement is relatively stable. The distance is about 10cm-2m. If this distance is exceeded, accidental inaccuracies often occur. Of course not Eliminate technical issues.)


The test object is the SRF-04 ultrasonic sensor, which has four pins: 5v power supply pin (Vcc), trigger control terminal (Trig), receiving terminal (Echo), and ground terminal (GND) 



How to use the module: 
Using this module, occupies two IO ports of the single-chip microcomputer, and one IO port is used as the trigger terminal. One IO port is used as the echo PWM signal capture pin. When writing the program, firstly set the level of 8 40K cycles at the TXD pin, and the program is processed into a PWM signal and output from the RXD pin. Once an echo signal is detected, the echo signal is output for our convenience. When we use it, we only need to read the low level time (T). The echo signal is a distance object proportional to the pulse width. The distance can be calculated from the time interval between the transmitted signal and the received echo signal. Formula: uS/58=cm or uS/148=inch. The formula L=340T/2 can also be propagated in the air by sound waves. You can find L (measured distance). If no reverberation signal is detected, the module’s reverberation signal pin will output a level of about 140uS to prevent the transmitted signal from affecting the reverberation signal. 


The working principle of the module: 

IO trigger ranging to at least 10us high signal;

module automatically sends eight 40kHz square wave, automatically detect whether a signal return;

a signal to return to a high IO output, high duration of the ultrasonic time from launch to return.

Test distance = (time high * speed of sound (340M / S)) / 2;


Circuit connection method: 



Arduino program example: 

const int TrigPin = 2
const int EchoPin = 3
float cm; 
void setup() 

Serial.begin(9600); 
pinMode(TrigPin, OUTPUT); 
pinMode(EchoPin, INPUT); 

void loop() 

digitalWrite(TrigPin, LOW); //Send a short time pulse to TrigPin  
delayMicroseconds(2); 
digitalWrite(TrigPin, HIGH); 
delayMicroseconds(10); 
digitalWrite(TrigPin, LOW); 

cm = pulseIn(EchoPin, HIGH) / 58.0//Convert the echo time to cm  
cm = (int(cm * 100.0)) / 100.0//Keep two decimal places  
Serial.print(cm); 
Serial.print("cm"); 
Serial.println(); 
delay(1000); 



TAG: spotpear SpotPear GPS LCD Driver Board ESP32 Thermal imaging camera Raspberry Pi Starlight Camera IR-CUT IMX462 (A) Sensor 2MP 90 Degree CM4 OpenWrt Tutorial NVIDIA Jetson Orin Nano Developer Kit Official Original 8GB AI 40Tops For Embedded and Edge Systems 1.69inch LCD TouchScreen Display 240×280 ST7789 Arduino Raspberry Pi ESP32S3 Pico STM32 Supports 6V~24V Solar Panel Mini Uninterruptible Power Supply module Supports charging And Power output at the same time 5V 2.5A Screen 1.47 inch LCD AXS5106L TouchScreen JD9853 Display 172x320 For Arduino/Raspberry Pi/Pico/ESP32 DPI Interface Raspberry Pi 3.5 inch LCD F Display Capacitance TouchScreen 60fps ST7796 GT911 320x480 Also For Arduino/Pico2/ESP32/RP2040/RP2350 ESP32 C6 Development Board 1.47 inch LCD Touch Screen 1.47inch Display 172×320SD AXS5106L JD9853 Digital Photo Frames NVIDIA Jetson Orin Nano 4/8GB AI 20/40Tops Lower Power Autonomous Machines BPI-M4 Zero ESP32-S3 1.28inch PoE-M.2-HAT+B User Guide