The HC-SR04 sensor
The HC-SR04 is a widely used ultrasonic distance sensor module that is popular in electronics projects, particularly in robotics and automation. It operates based on the principle of echolocation, emitting ultrasonic pulses and measuring the time it takes for them to bounce back to calculate distance. This sensor typically operates at 5 volts DC however, we are operating it on the 3.3 Volts provided by the micro-controller. It operates in two main modes: trigger and echo. In trigger mode, it sends out a short pulse to initiate the measurement process, while in echo mode, it listens for the returning echo. Interfacing the HC-SR04 with the Raspberry Pi Pico is straightforward, requiring only four connections: VCC (5V), GND, Trigger, and Echo. To measure the distance using the HC-SR04, we send a trigger pulse, wait for the echo pin to go high, measure the time the echo pin stays high, and calculate the distance based on the time taken and the speed of sound in air.
