The HC-SR04 ultrasonic sensor is an inexpensive and extremely popular sensor that measures the distance to an object in front of it and indicates this in centimeters or inches. This variant is integrated on a board with an Attiny microcontroller, which transmits measurement data digitally via the easyC connection to a microcontroller such as Arduino (or a compatible board such as Dasduino), thus enabling simple connection. https://elecena.pl/product/25844131/333001-developer-boards-ultrasonic-distance-sensor-hc-sr04 2024-05-10 https://elecena.pl/product/25844131/333001-developer-boards-ultrasonic-distance-sensor-hc-sr04 2025-12-30