PIC microcontroller based ultrasonic distance measurement

Abstract

Classical measurement methods cannot be used at situations in which distance between two objects is constantly changing. Therefore, ultrasonic sound is used for distance measurement because it has high energy, it can easily reflect from hard surfaces and it follows linear-straight path. At ultrasonic distance measurement, the return time of the sound pulse that is generated from sound source is measured and object’s distance from sound source is determined by using speed of sound. In the study, 40 kHz ultrasonic ultrasonic receiver-transmitter pair is used for distance measurement. Trigger pulse which is appropriate to ultrasonic transmitter is provided by the PIC microcontroller. The time that passes between transmitter and receiver is evaluated by microcontroller. After that, distance is calculated and displayed on the LCD screen with sensivity of 0.1 cm. Also the data can be recorded with 750 ms sampling time and 12 bit resolution. But recording capacity is limited with PIC’s EEPROM. If required, recording capacity can be increased with AT24C512 EEPROM and the data can be transferred into the computer via serial port. In the paper, the distance measuring system developed will be discussed in detail with system’s set up and operation.