ChApTEr 2 ■ hArdwArE for IoT SoluTIonS
Sparkfun MicroSD Shield
The last shield in my list of example Arduino shields is the Sparkfun MicroSD shield. It is simply a shield
with a MicroSD card reader. There are other variants of this shield available, but I like the Sparkfun version
because it also comes with a prototyping area, making it possible to build your own circuit on the shield and
giving your solution a convenient platform and a MicroSD reader to boot. Figure 2-23 shows the Sparkfun
MicroSD shield.
XBee Modules
The next hardware option I will discuss is not specifically an Arduino shield or even meant to be used
exclusively with the Arduino. As you will see, the XBee is a versatile module used for low-cost, low-power
(as in resources) communication.
The XBee is a self-contained module that uses radio frequency (RF) to exchange data from one XBee
module to another. XBee modules transmit on 2.4GHz or long-range 900MHz and have their own network
protocols.
The XBee module itself is small—about the size of a large postage stamp—making it easy to incorporate
into small projects such as sensor nodes. The modules are also low power and can use a special sleep mode
to further reduce power consumption.
Although the XBee isn’t a microcontroller, it does have a limited amount of processing power that
you can use to control the module. One of these features, the sleep mode, can help extend battery life for
Figure 2-23. Arduino microSD shield from Sparkfun