Exploring Arduino, 2nd Edition

9Shift Registers

Parts You'll Need for This Chapter

• Arduino Uno or Adafruit METRO 328
• USB cable (Type A to B for Uno, Type A to Micro-B for METRO)
• Half-size or full-size breadboard
• Assorted jumper wires
• 220Ω resistors (×8)
• 5 mm red LEDs (×8)
• 5 mm green LEDs (×4)
• 5 mm yellow LEDs (×3)
• Sharp GP2Y0A21YK0F IR distance sensor with JST cable
• SN74HC595N shift register
  • CODE AND DIGITAL CONTENT FOR THIS CHAPTER
  • Code downloads, videos, and other digital content for this chapter can be found at:
  • exploringarduino.com/content2/ch9
  • Code for this chapter can also be obtained from the Downloads tab on this book's Wiley web page:
  • wiley.com/go/exploringarduino2e

As you plug away building exciting new projects with your Arduino, you might already be thinking: “What happens when I run out of pins?” Indeed, one of the most common uses for the Arduino platform is to put an enormous number of blinking LEDs on just about anything. Light up your room! Light up your computer! Light up your dog! Okay, maybe not that last one.

But there's a problem: What happens when you want to start blinking 50 LEDs (or controlling other digital outputs), but you've used up all of your I/O pins? That's where shift registers can come in handy. With shift registers, you can expand the I/O capabilities of your Arduino without having to pay a lot more for an expensive microcontroller with additional I/O pins. In this chapter, you'll learn how shift registers work, and you'll implement both the software and hardware necessary ...