超声波介绍 HC SR04 Ultrasonic Module User Guide

HC-SR04_ultrasonic_module_user_guide

HC-SR04_ultrasonic_module_user_guide

HC-SR04_ultrasonic_module_user_guide

HC-SR04%20User%20Guide

hc-sr04_ultrasonic_module_user_guide

User Manual:

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Page Count: 4

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HC-SR04 User Guide

The transmitter emits a 8 bursts of an directional 40KHz ultrasonic wave when

triggered and starts a timer. Ultrasonic pulses travel outward until they encounter

an object, The object causes the the wave to be reflected back towards the unit.

The ultrasonic receiver would detect the reflected wave and stop the stop timer.

The velocity of the ultrasonic burst is 340m/sec. in air. Based on the number of

counts by the timer, the distance can be calculated between the object and

transmitter The TRD Measurement formula is expressed as: D = C X T which is

know as the time/rate/distance measurement formula where D is the measured

distance, and R is the propagation velocity (Rate) in air (speed of sound) and T

represents time. In this application T is devided by 2 as T is double the time

value from transmitter to object back to receiver.

1. Ultrasonic Distance Measurement Principles

2. Product Features

Features

� Stable performance (Xtal.)

� Accurate distance measurement

� High-density SMD Board

� Close Range (2cm)

Uses

� Robotics barrier

� Object distance measurement

� Level detection

� Security systems

� Vehicle detection/avoidance

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4. Module Pin Asignments

PinSymbolPinFunctionDescription

VCC5Vpowersupply

Trig

Trigger Input pin

Echo

Receiver Output pin

GNDPowerground

ElectricalParametersHC-SR04UltrasonicModule

OperatingVoltage

5VDC

OperatingCurrent15mA

OperatingFrequency

40KHz

Max. Range4m

NearestRange2cm

MeasuringAngle 15 Degrees

InputTriggerSignal

10us min. TTL pulse

OutputEchoSignal

TTL level signal, proportional to

distance

Board Dimensions 1-13/16" X 13/16" X 5/8"

3. Product Views

5. Electrical Specifications

1

2

3

4

4 X 0.1" Pitch Right Angle Header Pins

Board Connections

WARARNING

Do Not connect Module with Power Applied! Always apply power after connecting

Connect "GND" Terminal first

144 1

FRONT BACK

6. Module Operation

Set Trig and Echo Low to initalize module. Place a minimum 10us High

level pulse to "Trigger" (module will automatically send eight 40KHz acoustic

bursts). At the same time, Gate the microcontroller timer to start timing.

Wait to capture the rising edge output of ECHO port to stop the timer. Now

read the time of the counter, which is the ultrasonic propagation time in the air.

According to the formula: Distance = (ECHO high level time X ultrasonic

velocity (Speed of Sound in air 340m/sec) / 2, you can calculate the distance to

the obstacle.

For best results and maximum range, the Object should be larger than 0.5M2

the nearer the target object, the smaller it may be

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--10us--

>50us

8x40KHz

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HC-SR04 ULTRASONIC MODULE

Trigger

40KHz

Acoustic

Burst

40KHz

Reflected

Signal

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~~

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Propagation Delay

Dependent on Distance

Output of

ECHO Pin

Information obtained from or supplied by Mpja.com or Marlin P. Jones and Associates

inc. is supplied as a service to our customers and accuracy is not guaranteed nor is it

definitive of any particular part or manufacturer. Use of information and suitability for

any application is at users own discretion and user assumes all risk.

Trigger 10us min. start measurement from microcontroller.

Max Rep. Rate: 50us

ECHO Output pulse to microcontroller, width is the time from last of 8 40KHz

bursts to detected reflected signal (microcontroller Timer gate signal)

Distance in cm = echo pulse width in uS/58

Distance in inch = echo pulse width in uS/148

7. ModuleTiming

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