Ultrasonic range finder using 8051
A simple ultrasonic
range finder using 8051 microcontroller is presented in this article. This
ultrasonic rangefinder can measure distances up to 2.5 meters at an
accuracy of 1 centi meter. AT89s51 microcontroller and the ultrasonic
transducer module HC-SR04 forms the basis of this circuit. The ultrasonic
module sends a signal to the object, then picks up its echo and outputs a wave
form whose time period is proportional to the distance. The microcontroller
accepts this signal, performs necessary processing and displays the
corresponding distance on the 3 digit seven segment display. This circuit finds
a lot of application in projects like automotive parking sensors, obstacle
warning systems, terrain monitoring robots, industrial distance measurements
etc.
HC-SR04 ultrasonic module
HC-SR04 is an ultrasonic
ranging module designed for embedded system projects like this. It has a
resolution of 0.3cm and the ranging distance is from 2cm to 500cm. It operates
from a 5V DC supply and the standby current is less than 2mA. The module
transmits an ultrasonic signal, picks up its echo, measures the time elapsed
between the two events and outputs a waveform whose high time is modulated by
the measured time which is proportional to the distance. .The photograph
of an HC-SR04 module is shown below.
The supporting circuits
fabricated on the module makes it almost stand alone and what the programmer
need to do is to send a trigger signal to it for initiating transmission
and receive the echo signal from it for distance calculation. The HR-SR04 has
four pins namely Vcc, Trigger, Echo, GND and they are explained in detail
below.
1) VCC : 5V DC supply voltage is connected to
this pin.
2) Trigger: The
trigger signal for starting the transmission is given to this pin. The trigger
signal must be a pulse with 10uS high time. When the module receives a valid
trigger signal it issues 8 pulses of 40KHz ultrasonic sound from the
transmitter. The echo of this sound is picked by the receiver.
3) Echo: At this
pin, the module outputs a waveform with high time proportional to the
distance.
4) GND: Ground is
connected to this pin.
Circuit
Diagram:
Circuit diagram of Ultrasonic range finder using 8051
The ultrasonic module
is interfaced to the microcontroller through P3.0 and P3.1 pins. Port0 used for
transmitting the 8 bit display data to the display and port pins P1.0, P1.1,
P1.2 are used for transmitting display drive signals for the corresponding
display units D1, D2, D3. Push button switch S1, capacitor C3 and resistor R9
forms a de-bouncing reset circuitry. Capacitors C1,C2 and crystal X1 are
associated with the clock circuit.
Application
1. To measure the distance between two objects.
2. to fix the travelling distance of the vehicle
Price in jaipur Rs-3000
Price in other Cities Rs-3500
Contact- 7665409048/7689068784
Jaipur, Rajasthan
