## 11 Hardware and Testbeds
### Wireless Motes  
There are several devices of wireless motes that can be used as WMSN motes and most of them are available in commercial products as shown in Figure 5. Depending on their processing power and storage capacity, these wireless motes can be classified into three groups:  
**1) Lightweight-class Platforms:** The devices in this category are designed initially for detecting scalar data, such as temperature, light, humidity _etc._, and their main concern is to consume less amount of energy as possible. Therefore, these devices have low processing power capability and small storage and most of them are equipped with a basic communication chipset (e.g., IEEE 802.15.4 on CC2420 radio). The CC2420 chipset only consumes 17.4 and 19.7 mA for sending and receiving respectively and has maximum transmit power of 0 dBm with data rate of 250 Kbps. Table 4 shows examples of lightweight-class wireless motes, Mica-family motes [92] and FireFly [93], and compares their specifications.  
**2) Intermediate-class Platforms:** The devices in this group have better computational and processing capabilities and larger storage memory than lightweight-class devices. However, they are also equipped  
Figure 4: WMSN Platforms Classification.  
Figure 5: Examples of Wireless Mote Platforms.  
with low bandwidth and data rate communication module (e.g., CC2420 chipset which is IEEE 802.15.4 compatible). Tmote Sky [94] is an example of Intermediate-class mote designed by Moteiv (Sentilla) that uses low power 8 MHz 16-bit MSP430 F1611 RISC processor from Texas Instruments featuring 10 kB of RAM, and 48 kB of flash. Tmote Sky uses Chipcon CC2420 radio for IEEE 802.15.4/ Zigbee for maximum data rate of 250 Kbps. Tmote Sky has been used to implement camera mote with CITRIC [95] and CMUCam3 [96].  
**3) PDA-class Platforms:** The devices in this category are more powerful in terms of computational and processing power and they are designed to process multimedia content in a fast and efficient manner. These devices can run different operating systems (e.g., Linux, TinyOs, and run Java applications and.NET micro frameworks) and support multiple radios with different data rates (e.g., IEEE 802.15.4, IEEE 802.11, and Bluetooth). However, these devices consume relatively more energy. Stargate and Tmote2 are examples of PDA-class platforms. Stargate board [97], designed by Intel and manufactured by Crossbow, uses 400 MHz 32-bit Marvell's PXA255 XScale RISC processor with 32 MB of Flash memory and 64 MB of SDRAM and runs Linux operating system. It can be interfaced with Crossbow's MICA2 or MICAz motes for IEEE 802.15.4 wireless communication as well as PCMCIA IEEE 802.11 wireless cards or compact Flash Bluetooth. Thus, Stargate board can be used as a sensor network gateway, robotics controller card, or distributed computing platform. It forms a camera mote when it is connected with camera device (e.g., webcam) as shown in [98, 99, 100]. Tmote2 [101], also designed by Intel and manufactured by Crossbow, is a wireless sensor node platform built around the low-power 32-bit PXA271 XScale processor and integrates an 802.15.4 radio (CC2420) with a built-in 2.4 GHz  
antenna. It can operate in the range 13-416 MHz with dynamic voltage scaling and includes 256 KB SRAM, 32 MB Flash memory, 32 MB SDRAM, and several I/O options. It can run different operating systems such as TinyOs and Linux with Java applications and it is also available with.NET micro framework. It integrates many I/O options making it extremely flexible in supporting different sensors including cameras, A/Ds, radios, _etc._ The PXA271 processor includes a wireless MMX coprocessor to accelerate multimedia operations and add media processor instructions to support alignment and video operations. Imote2 has been used as a camera more in [102; 103].