Introduction to IoT Devices

by Andy Slote - Dec 01 2019

All Posts Introduction to IoT Devices

The Internet of Things will bring huge numbers of devices into operation for business and consumer applications. What are these devices? If we take a look inside, what would we see?

There are different opinions of what fits in the IoT device category, depending on who you ask. Things that are relatively complex such as mobile phones or specialized computers, may fit within some people’s definition, but for this introduction, let’s stick with the more common characterization of them as relatively simple endpoints in an IoT network.

Inside will be one or more sensors to capture data. A wide range of sensors are available, but many applications require common measurements like temperature, humidity, light, pressure, acceleration, etc. Devices can also employ actuators that function inversely to a sensor, causing actions in the physical environment. Examples include opening or closing valves, turning on/off irrigation equipment, and triggering door locks.

As sensors create data, getting that data to where it can be useful (an application, often in a cloud environment) requires connectivity. Hard-wired connections exist in many settings, but a need to transmit data wirelessly is vital to a vast number of use cases. Radio Frequency (“RF”) modules enable and manage these connections, and the types available are many. So many that more than one choice often exists for consideration. Popular options include Wi-Fi, Bluetooth, LoraWAN, and many cellular technologies (3G, 4G, etc.). An RF module requires a corresponding antenna, which is often inside the enclosure, as well. Cost, range, power, data criticality, and other factors determine the type of RF module chosen. 

Energy storage is essential, which means some type of battery is inside the case. These may be as familiar as the common alkaline types (AAA, AA, etc.) or a “coin cell” (similar to a watch battery). Many implementations aim to maximize battery life, ensuring devices can function for long periods, often years, without a replacement. Rechargeable batteries work for some use cases but typically last for a few months between charging. 

Devices also contain Power Management Units, which perform various functions critical to operations like monitoring power connections, assessing battery charge levels, and controlling power to integrated circuits. Some contribute to extending battery life, including shutting down unnecessary system components when left idle, reducing communications strength, disabling sensors at specified intervals, and controlling sleep and power functions (on/off). PMU also manages the recharge of batteries, should they be of that type.

Although the device firmware is updateable wirelessly for some technologies, most devices include a direct connection. The most common are USB-type, which is also a means for recharging batteries.

More sophisticated devices exist, with more diverse electronic components inside, but the elements described here are the most prevalent.