Building iPhone and iPad Electronic Projects

Chapter 9. Peer-to-Peer Bluetooth Low Energy

About This Chapter

Prerequisites

Read Chapter 6 first to get a basic understanding of Bluetooth low energy technology.

Equipment

You will need two iOS devices. Each must be either an iPhone 4S or later, an iPad 3 or later, or an iPod 5th Gen or later running iOS 6 or later.

Software

You will need a copy of techBASIC or techBASIC Sampler.

What You Will Learn

An iPhone was used to connect to an external Bluetooth low energy device in the three previous chapters. This chapter reverses the connection. You will see how to make the iPhone itself become the Bluetooth low energy device, broadcasting information for Bluetooth low energy–compatible controllers to see. We’ll put this to use to create a program that performs peer-to-peer communications between two iOS devices.

Bluetooth low energy is normally limited to short, 20-byte packets of information. The program in this chapter also shows how to send longer files.

Bluetooth Low Energy Slave Mode

So far, all of our Bluetooth low energy projects have used the iPhone or iPad to access peripherals that offer information to any Bluetooth low energy device. The peripheral, like the Texas Instruments SensorTag or the RedBearLab BLE Shield, is called the slave device, while the consumer of the information—in our case, the iPhone or iPad—is called the central device.

But what if we want things to go the other way? What if we want the iPhone to be the peripheral, sending information to other devices that subscribe ...