After buying a HC-SR04 from Amazon, I could not get it to work out of the box. Not wanting to concede I had a DOA sensor on my hands, I searched for a simple example setup. After spending far too long on this than I felt I needed to, I decided to make this instructable to help other emerging tinkerers get their project off the ground.
I admit this example is more than bare-bones in that it has LEDs, but this lets me test it without needing a PC to show distance and check the accuracy of the sensor.
Step 1: Parts List
Arduino UNO R3 (I use the Adafruit mount)
One (1) HC-SR04 Ultrasonic Sensor
One (1) Red LED
One (1) Green LED
Two (2) 560 ohm (Green, Blue, Brown, Gold) Resistors
Eight (8) Male/Male hookup wires
A ruler that measures centimeters (or use the serial monitor)
Step 2: Connect the components
Connect the components and wires as shown in the two pictures.