MICROCONTROLLER BASED ULTRASONIC DISTANCE MEASUREMENT
The microcontroller based ultrasonic distance measuring device is a device used to calculate the distance between the ultrasonic transmitter/receiver and the object whose distance is to be measured. A microcontroller is used to calculate the delay time between the transmitted signal and the received signal.
Ultra means “beyond” and sonic means “sound”. Ultrasonic refers to sound waves that have higher frequency than the human audible range. The sound waves whose frequency lies above the audible frequency of 20 kHz are called Ultrasonic waves.
Ultrasonic sensors can detect small objects at considerable distances. They are able to disregard disturbing backgrounds and functions in fog, dust, dirt or extreme lighting is possible. They can detect any soft and hard materials. No correction factors have to be applied and color does not matter. In our project we are using two ultrasonic sensors. One is ultrasonic transmitter and the other is ultrasonic receiver. They transmit and receive the signal with 40 KHz frequency.
DESCRIPTION OF BLOCK DIAGRAM:
This circuit is designed to measure the distance of the object with the help of ultrasonic waves. The 12F675 microcontroller is used to generate the 40 KHz frequency signal. This signal is given to level logic converter (MAX232) in order to convert the TTL output pulse to +12V and -12V pulse. Then this pulse is transmitted through ultrasonic transmitter.
The ultrasonic waves spread in the air and hit the nearest object and reflected. The reflected signal from the object is received by the ultrasonic receiver. The received wave is given to the amplifier in order to amplify the received weak signal.
After amplification the amplified wave is given to zero adjustment amplifier because the amplified wave is in the range of above 6V level.
The output of amplifier