Exploring Arduino, 2nd Edition

10The I²C Bus

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)
• 4.7kΩ resistors (×2)
• 5 mm red LED
• 5 mm green LEDs (×4)
• 5 mm yellow LEDs (×3)
• SN74HC595N shift register
• TC74A0-5.0VAT I²C temperature sensor
  • CODE AND DIGITAL CONTENT FOR THIS CHAPTER
  • Code downloads, videos, and other digital content for this chapter can be found at:
  • exploringarduino.com/content2/ch10
  • Code for this chapter can also be obtained from the Downloads tab on this book's Wiley web page:
  • wiley.com/go/exploringarduino2e

You've already learned how to connect both analog and digital inputs and outputs, but what about more complicated devices? The Arduino (or any microcontroller, for that matter) can expand its capabilities by interfacing with a variety of external components. Many integrated circuits (ICs) can implement standardized digital communication protocols to facilitate communication between your microcontroller and a wide array of possible modules. This chapter explores the I²C bus (pronounced “eye squared see” or “eye two see”).

The I²C bus enables robust, high-speed, two-way communication between devices while using a minimal number of I/O pins to facilitate communication. Usual maximum speeds range from 100 kilobits per second (Kbps) up to a few megabits per second (Mbps), depending on the components and system design. An I²C bus is controlled ...