With each contact you make, the red LED lights up ... with only an Arduino UNO, ultrasonic sensor, force-sensitive resistor (or push button), and piezo buzzer. The tone generated depends on ...

Inside [Klaus]’ device is an Arduino Uno, an HC-SR04 ultrasonic distance sensor, and an Adafruit Wave Shield. Originally, this parking/distance sensor used a small TFT to display the distance to ...