The focus of the internet is set to change
over the next five years as systems become
smarter. According to networking specialist
Cisco, 50 billion devices are likely to be con-
nected to the internet by 2020, helping to sus-
tain a $14 trillion market. The systems that
dominate the internet today, such as PCs, lap-
tops, tablets and smartphones, will be dwarfed
by the tens of billions of machines with network
connections that will relay data to each other
with the aim of making life more efficient.
The idea of the Internet of Things (IoT) dates
back to the late 1990s when researchers pro-
posed ideas such as ambient intelligence, in
which a forest of smart sensors would monitor
environmental conditions, alerting control sys-
tems to changes. By enacting changes in re-
sponse, these control systems can improve ef-
ficiency in a wide range of systems, from in-
dustrial control through home automation to
healthcare. For example, a set of smart sensors
dotted around the body, can pick up on health
problems that alert the user to a problem
through their phone. In industrial control, a
series of sensors mounted along a production
line can detect conditions that may lead to
problems such as sudden changes in tempera-
ture or excess vibration that may signal a prob-
lem in a machine tool or a process going
outside its bounds. There are three fundamental
components that combine to form an IoT
node: intelligence, sensing, and wireless com-
munications. Wireless connectivity is vital be-
cause it will allow sensor nodes to be deployed
quickly and easily without the requirement to
route network cables to each location. In order
to survive for long periods of time on a single
battery charge, an IoT node needs to exhibit
low power consumption. Typically, the node
will be dormant for long periods of time, wak-
ing up for short periods to take a reading and
then making a decision whether to send out
an alert based on the change or go back to
sleep. A large number of microcontrollers are
designed around this core requirement, sport-
ing ultra low energy sleep modes combined
with high-performance instruction pipelines
to streamline processing while awake.
A key decision is the type of architecture. A
growing number of low-cost microcontrollers
from vendors such as Atmel, Freescale, STMi-
croelectronics and Texas Instruments use 32-
bit cores based on architectures such as ARM
to deliver high performance at low power and
access to a growing range of open-source soft-
ware that allows applications to be built quickly.
However, architectures such as Atmel AVR
demonstrate that the 8-bit platform still pro-
vides a great deal of power, using advanced
smart peripherals to collect data from sensor
interfaces, and delivering high cost-effectiveness.
There are a number of possible approaches for
introducing low-power communications to an
IoT node, ranging from purpose-designed pro-
tocols such as ZigBee to low-power variants of
Bluetooth and Wi-Fi. Some of these protocols
offer direct compatibility with the internet pro-
tocol (IP). Others rely on a gateway to map be-
tween IP packets and the leaner protocols used
by the IoT sensor nodes. ZigBee is a low-power
wireless network specification based on the
IEEE 802.15.4 (2003) standard that was devel-
oped by a group of 16 companies involved in
industrial and building automation. A novel
aspect of ZigBee compared to many other net-
working protocols lies in its use of mesh net-
working. This allows IoT nodes far away from
a central controller to use nodes in between to
carry their communications. This not only ex-
tends the range of a central gateway, it also in-
creases robustness as a transmission can use a
number of different routes through the mesh.
The fundamental components of
the Internet of Things
I
NTERNET
-
OF
-T
HINGS
By Mark Zack,
Digi-Key
As the Internet of Things
scales up, more integrated
solutions will arrive on the
market. But already there are
many choices available to the
engineer whereby the three
key components of IoT sup-
port can be incorporated,
namely intelligence, sensing,
and wireless communications.
This article reviews some of
the options.
June 2014
30
Figure 1. Comparing data rates of RF systems
