The SparkFun Ultrasonic Distance Sensor - TCT40 (sen-24805) a user-friendly upgrade to the popular HC-SR04 sensor, offers non-contact distance measurement from 2cm to 400cm with an accuracy of 3mm.

Bonezegei_HCSR04 is a simple and easy-to-use Arduino library for interfacing HCSR04 ultrasonic sensor module. The library provides functions for measuring distance, setting trigger and echo pins. The ...

Paul and David Bradt’s Ardiono Projects offers multiple ways to use Arduino and Raspberry Pi microcontrollers for your model railroading projects. Buy the book here. Code for Button/Blink Test (SN095) ...