The PSoC Range Finder is a simple, inexpensive ultrasonic distance meter that requires only the PSoC device, two 40-kHz ultrasonic transducers, two resistors, and two capacitors. Typical applications include positioning for robotics, generic distance measurement, and liquid-level measurement without contact.

The circuit uses two PWM channels of ATmega8 for controlling the speed and direction (reverse, forward) of the car, based on the command received from the IR remote. Here, a Sony TV remote was used. The IR codes were received by using TSOP1738 IR detector from Vishay.

The robot is controlled by a NXT-G program that listens to Bluetooth messages that tell it what to do. Normally, the commands are movement commands. These commands control the speed of the robot, whether it will go straight or turn left or right, or whether it will stop. It can also receive a command to do a radar-style scan with the ultrasonic sendor. When it gets such a command, it stops moving, and performs a sequence of ultrasonic measurements while rotating the sensor. It sends these measurements, along with data about what angle the sensor was looking at, back to the PC. When the scan ends, the robot starts responding to movement commands again.

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