Summary

In this chapter you have learnt how to interface an ultrasonic sensor. I have also introduced a few uses of the sensor to give you a feel for how it can be used in your own projects. Sensors such as these are often used in hobby robotics projects for the robot to sense if it is near a wall or other obstacle. I have also seen them used in gyrocopter projects to ensure the craft does not bump into any walls or people. Another common use is to detect the height of a liquid inside a tank or a tube. I am sure you will think of other great uses for these kinds of sensors.

Subjects and Concepts covered in Chapter 14

• How an ultrasonic sensor works
• How to read the PW output from the MaxSonar devices
• Using a capacitor to smooth the power line
• How to use the pulseIn command to measure pulse widths
• Various potential uses for an ultrasonic range finder
• How to use the MAX7219 to control 7-segment displays
• How to wire up a common cathode 7-segment display
• Using a running average algorithm to smooth data readings
• How to use the setDigit() command to display digits on 7-segment LEDs
• Using division and modulo operators to pick out digits from a long number
• How to make an infinite loop with a while(1) command