How Ultrasonic Sensor Works An ultrasonic sensor is a very useful sensor that measures distances with sounds. We used the PIC16F628A microcontroller for this project. This microcontroller has TMR1 which we are going to use. We need 2 I/O pins for TRIG and ECHO pins. For showing distance, we used an LCD. For more information about the LCD library and usage click the button below. LCD Interfacing with PIC Using XC8