The width of the trigger signal should be at least 10 microseconds.

To measure distance with the HC-SR04 ultrasonic sensor, we provide a 10us trigger signal from the pic microcontroller to trigger pin of the sensor. How to Measure Distance with HC-SR04 Ultrasonic Sensor Moreover, a 16×2 LCD is used to display the measured value of distance on an LCD. PIC16F887 microcontroller will be used to read ultrasonic sensor output signals. But the code works with the HY-SRF05 sensor also. We will be using HC-SR04 for distance measurement. But 1mm is not an issue when measuring distance in the units of cm and meter. Both sensors have the same electrical properties and can be used in replacement for each other except HY-SRF05 has one 1mm better precision than HC-SR04. In this tutorial, we will be using HC-SR04 ultrasonic sensor but there is another version of this sensor which is HY-SRF05. Before we proceed further with this tutorial, we recommend you to read about ultrasonic sensors and its working here: This sonar sensor has important and useful applications for embedded systems projects such as contactless range meter, contactless water level measurement, and sonar system. But the concepts, you will learn to interface the HC-SR04 ultrasonic sensor with any pic microcontroller remain the same. In this tutorial, we will learn to interface HC-SR04 ultrasonic sensor with pic microcontrollers and how to measure distance with the HC-SR04 ultrasonic sensor? There are a variety of Pic microcontroller chips available.

Proximity sensor in proteus