Distributed Network Data

Chapter 7. Building Point-to-Point XBee Networks

Up until now, our Arduino has been connected to our computer via a USB cable. In order to use our Arduino and the attached sensors in the environment, we need to eliminate the USB cable and replace it with a wireless connection.

In the past, adding wireless communication to a project required extensive electrical engineering expertise. The available off-the-shelf wireless modules (Figure 7-1) were typically bulky proprietary technologies that required customization and debugging to use with a particular application.

Today, we have many compact, easy-to-use modular wireless solutions available to us. These modules use commonplace standards like Wi-Fi, GSM/CDMA (cellular telephone), Zigbee, and Bluetooth. Each one of these standards has tradeoffs that make them more or less appropriate for a particular application.

One of the standards used most commonly when dealing with sensor networks is IEEE 802.15.4. This protocol focuses on low-cost, low-speed communication between devices and is intended for low-power scenarios. It is the basis for the higher-level ZigBee protocol (also commonly used when dealing with sensor network), which further extends the standard by developing the upper layer protocols to enable mesh networking between devices.

Figure 7-1. Aerocomm module

While many other brands of 802.15.4-based hardware exist, probably the most ...