超声波介绍 HC SR04 Ultrasonic Module User Guide

1

HC-SR04

HC-SR04 User

User

User Guide

Guide

Part

Part 1

1

1 U

U

U ltrasonic

ltrasonic

ltrasonic Introduction

Introduction

1.

1. 1

1

1 Ultrasonic

Ultrasonic

Ultrasonic Definition

Definition

The human ear can hear sound frequenc y around 20HZ ~ 20KHZ, and

ultraso nic is the sound wave beyond the human ability of 20KHZ .

1.2

1.2 Ultrasonic

Ultrasonic

Ultrasonic distance

distance

distance measurement

measurement

measurement principle

principle

Ultrasonic transmitter emit ted an ultrasonic wave in one direction, and started

timing when it launch ed. U ltrasonic spread in the air, and would return

immediately when it encounter ed obstacles on the way . At last, the ultrasonic

receiver would stop timing when it receive d the reflected wave. As Ultras onic

spread velocity is 340m / s in the air , based on the timer record t

t

t, we can

calculate the distance (s) between the obstacle and transmitter, namely: s =

340t / 2, which is so- called time difference distance measurement principle

The principle of ultrasonic distance measurement use d the already- known air

spreading velocity, measuring the time from launch to reflection when it

encountered obstacle , and then calculate the distance between the transmitter

and the obstacle according to the time and the velocity. Thus, the principle of

ultrasonic distance measurement is the same with radar.

Distance Measurement formula is expressed as: L = C X T

In the formula , L is the measured distance, and C is the ultrasonic spreading

velocity in air, also, T represents time (T is half the time value from transmit ting

to receiving ).

2

1.3

1.3 Ultrasonic

Ultrasonic

Ultrasonic Application

Application

U ltrasonic Application

T

echnology is the thing which developed in recent

decades . W ith the ultraso nic advance , and the electronic technology

development, especially as high-power semiconductor device technology

matures, the application of ultra sonic has become increasingly widespread:

�Ultrasonic measurement of distance, depth and thickness;

�Ultrasonic testing;

�Ultrasound imaging;

�Ultrasonic machining, such as polishing, drilling;

�Ultrasonic cleaning;

�Ultrasonic welding;

Part

Part 2

2

2 HC-SR04

HC-SR04

HC-SR04 Ultrasonic

Ultrasonic

Ultrasonic Module

Module

Module Introductio

Introductio

Introductio n

n

2.1

2.1 Product

Product

Product Features

Features

�Stable performance

�A ccurate distance measure ment

�H igh-density

�S mall blind

A

A pplication

pplication

pplication A

A

A reas:

reas:

�Robotics barrier

�O bject distance measurement

�L evel detection

�P ublic security

�P arking detection

3

2.2

2.2 Product

Product

Product Image

Image

2.3

2.3 、

、

、Module

Module

Module pin

pin definitions

definitions

Types Pin Symbol Pin Function Description

HC-SR04

VCC 5V power supply

Trig Trigger pin

Echo Receive pin

GND Power ground

2.4

2.4 、

、

、Electrical

Electrical

Electrical parameters

parameters

Electrical P arameters HC-SR04 Ultrasonic Module

Operating Voltage DC-5V

Operating Current 15mA

Operating Frequency 40KHZ

Farthest Range 4m

Nearest Range 2cm

Measuring A ngle 15 Degree

Input T rigger S ignal 10us TTL pulse

Output Echo S ignal

O utput TTL l evel s ignal, proportional

with range

Dimensions 45*20*15mm

4

2.5

2.5 Module

Module

Module operating

operating

operating Principle

Principle

S et low the Trig and Echo port when the module initialize s , firstly, transmit

at least 10us high level pulse to the Trig pin (module automatically sends eight

40K square wave), and then wait to capture the rising edge output by echo port,

at the same time, open the timer to start timing. Next, once again capture the

falling edge output by echo port , at the same time, read the time of the counter,

which is the ultrasonic running time in the air . A ccord ing to the formular: test

distance = (high level time * ultrasonic spreading velocity in air ) / 2 , you can

calculate the distance to the obstacle .

Part3

Part3 Use

Use

Use Freaduino

Freaduino

Freaduino UNO

UNO

UNO to

to

to test

test

test HC-SR04

HC-SR04

3.1

3.1 Freaduino

Freaduino

Freaduino uno

uno

uno and

and

and HC-SR04

HC-SR04

HC-SR04 Connection

Connection

Connection Description ：D2<------>Trig D3<------>Echo ( The user s

can define the connection pin by themselves)

Note ：You need to set the Freaduino UNO switch in 5V Side when use

together with HC-SR04 Module.

5

3.2

3.2 HCSR04

HCSR04

HCSR04 library

library

library function

function

function description

description

Long

Long timing()

timing()

Function name: timing

Parameters: None

Return Value: the time of ultrasonic from the transmitter to the receiver

float

float CalcDistance(long

CalcDistance(long

CalcDistance(long microsec,int

microsec,int

microsec,int metric)

metric)

Function name

：

CalcDistance

�microsec: the time of ultrasonic from the transmitter to the receiver

�metric: Set the unit of the return value ( the value of 1 for cm, and the value

of 0 for in )

Return Value : the measured distance

3.3

3.3 Add

Add

Add the

the

the HC-SR04

HC-SR04

HC-SR04 Library

Library

Step1:Download the Demo Code of HCSR04 Ultrasonic from address

http://www.elecfreaks.com/store/download/product/Sensor/HC-SR04/HCSR04Ultrasonic_demo.zip and

then unpack it to get the file of HCSR04 Ultrasonic .

Step2: Add the file of HCSR04 Ultrasonic in the file of Arduino-1.0.X / libraries.

Step3:If you can see the Example of HCSR04 Ultrasonic in Arduino IDE, the

adding of HC-SR04 library has been successful.

3.4

3.4 Test

Test

Test the

the

the Module

Module

Module with

with

with the

the

the Examples

Examples

Examples of

of

of Library

Library

Library File

File

1. Open Arduino IDE 1.0.X, and choose the corresponding board and

serial port.

2. Click file/ examples/ HCSR04Ultrasonic until the code pop up.

3. Compiling sketch until Done uploading appears, which represents the

uploading has been successful.

4. Open serial monitor and set the corresponding BaudRate.

5. If you see similar information in serial monitor as below, you succeeded.

6

Chart 3 、HC-SR04 testing results

超声波介绍 HC SR04 Ultrasonic Module User Guide

HC-SR04_Ultrasonic_Module_User_Guide

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