By Microchip Technology
Six Connectivity Options for IoT
This article explores the pros and cons of connectivity options for IoT edge device design.
In my opinion, the internet connection at my apartment is slow. Really slow. Debilitatingly slow. In fact, streaming Netflix over my connection is so uncertain that starting a new show feels like gambling. I’m persistent, but I’m barely through the 2nd season of The Crown.
During the day when I’m at my job working with IoT edge designs, however, my perspective on network speeds are completely different. For example, last week I was configuring a remote weather sensor to occasionally send small packets of data to a cloud server. The simplicity of that application makes the 10 Mbps I use to stream The Crown over my home network seem like a royal indulgence.
Unlike humans, IoT edge devices do not check email (lucky them) or indulge in streaming TV shows, so they don’t require the high data rates used in consumer electronics.
But similar to humans, IoT devices seem to cluster together in communities. IoT systems often consist of hundreds, or thousands, of connected edge devices. At that scale, seemingly simple design considerations become critical to the success of your product. One difficult design decision you will make is determining how your device connects to a network.
This guide will give you an overview of the most common types of connection methods utilized in IoT applications. Follow along to weigh your options and determine how you want to put the ‘I’ in your IoT design. Ethernet Ethernet is a fast and reliable way to connect things to the internet. Commonly found in industrial and building automation, Ethernet shines in systems that include many nodes on the same network. While no network is perfectly secure, it would be a great feat for hackers to break into a private Ethernet network remotely. Power Over Ethernet (PoE) also provides the capability to power your device through the Ethernet cable, which eliminates the need for a separate power cable.
Hardwiring does, however, present significant design challenges, and certainly does not make sense for every application. Nodes connected by Ethernet must be close to a router. Even in short distance applications, such as home and building automation, Ethernet cabling is so bulky that managing and hiding the wires presents a major challenge. Modern buildings can be constructed to accommodate automated lighting systems but installing an Ethernet IoT system in a building not designed for it is often not feasible.
Wi-Fi®
Wi-Fi is the go-to for internet connection and my grandmother’s favorite reason to call me. It provides speed and direct internet connection without the hardwiring constraints of Ethernet. Mainstream devices are also compatible with Wi-Fi, meaning that interfacing with your design can be as simple as reaching for a cell phone or laptop. Despite its prevalence, adding Wi-Fi capability to an embedded design is typically complex. Wi-Fi is attractive because it is wireless and fast, but those features come at the expense of security vulnerabilities and power consumption. As a result, Wi-Fi-based IoT designs require an engineer to delicately balance security, power and cost.
Luckily, solutions exist today to help reduce the complexity in Wi-Fi design. Using a Wi-Fi module that has been optimized for IoT will simplify your design and save development time. Modules like the ATWINC1500 are fully certified, support security protocols and are optimized for battery-powered devices, enabling Wi-Fi connectivity without compromising on cost and power consumption.
Low Power Wide Area Network (LPWAN)
LPWANs are less common in consumer products, so you may not be as familiar with them. They are, however, very popular with IoT systems that require extensive range, such as environmental monitoring. The beauty of using IoT for environmental monitoring is that we can monitor rural, offshore and generally inaccessible areas. The issue is that these locations are rural, offshore and generally inaccessible. You cannot give a device floating in the Mariana Trench a quick recharge or connect to Wi-Fi in the Sonoran Desert.
Max ranges in typical LPWAN use seem to hover around 10 kilometers (km). Data is transferred at very slow rates, but unless your IoT solution is checking email and streaming videos, you probably will not need a high-speed connection. While commonly used in agricultural and remote applications, LPWANs aren’t exclusive to them. Urban usage is growing, and one of the largest LPWAN commercial IoT deployments in North America is used to track vehicles in auction lots. There are two common LPWAN protocols: LoRaWAN™ (from Long Range, or LoRa®) and Sigfox. One difference between the two is cost. Sigfox is a subscription-based service and operates similarly to cellular. If Sigfox is available in your area, you can connect through a subscription with a local provider. With LoRaWAN, developers can avoid a subscription fee by creating a “do-ityourself” network, but most still opt to use a local network provider’s LoRa gateway infrastructure and pay a per-usage fee.
Cellular
Cellular coverage blankets much of the world. For embedded systems that need this range, cellular is the only option. However, it is expensive. You must use a provider, and you cannot set up your own network without governmental regulatory approval. The cost of the embedded components and provider subscriptions for each node often outweigh the benefits of cellular networks’ extensive reach. That said, it is important to distinguish the cellular network used for connecting things and the bill you cough up once a month for your phone. IoT-specific cellular networks are popping up to compete with LPWANs. A growing IoT cellular network is LTE CAT-M. The M stands for “machine,” and it is a lower speed, lower cost, lower power option optimized for IoT. While you might be used to pricey cell bills, CAT-M plans are typically substantially less expensive than consumer plans. Other options for cellular IoT connections are CAT-0, CAT1 and the newer NB-IoT (NB for “Narrow Band”). As 5G rolls out, we can expect it to drive innovation in IoT. The higher speeds of 5G could enable more progress in cutting-edge IoT applications, such as autonomous vehicles, albeit at a higher price tag than IoT-targeted networks. 5G coverage is not nearly as pervasive as LTE or 3G, but it is expanding. Some industry analysts have predicted that 5G will reach up to 20 percent of the world’s population in the next five years.
Satellite
Cell coverage might blanket most of the populated world, but what if you want to connect things in spread-out, desolate areas? Satellite connectivity is used for IoT applications such as shipping logistics in remote regions of the Earth that are not covered by cellular service. While expected to change as satellite technology progresses, developing a satellite IoT application is not as accessible as other connectivity options. Many satellite constellations are reserved for defense use, but you can purchase modules from Iridium® and ORBCOMM®.
Bluetooth®
You’re probably also already familiar with Bluetooth. Both Bluetooth Classic and Bluetooth Low Energy (BLE) have max ranges exceeding 100 meters but are typically used for devices that are within a few meters of each other. In our daily lives, we see Bluetooth in accessories for our phone and PC – headphones, keyboards and display technology. Bluetooth is great for consumer electronics because it is low power (with BLE being exceptionally low power), widely supported and pairs quickly. Unlike Wi-Fi, Bluetooth does not directly connect to the internet. You will need to set up a gateway to connect to the internet. While setting up your own gateway may seem daunting, it’s often as easy as connecting to a mobile device that also connects to Wi-Fi. Bluetooth 5 is a recent update that extends Bluetooth’s range so that it can be used in home area networking. Whereas Bluetooth Classic and BLE are typically used to connect devices that are mere meters apart, you can connect an entire home with Bluetooth 5. This extended range brings Bluetooth into the realm of home automation, lighting and industrial applications.
Implementation Recommendations
A major way these connectivity methods vary is in ease of implementation. It is easier to prototype with commonly used networks, such as Bluetooth Classic and BLE, because you are likely in possession of one or many compatible devices (e.g. your cellphone). This enables you to connect to your prototype easily and evaluate your design more quickly. Several certified BLE modules are available to consumers, and many come with open source code and tutorials on how to program them. Most modules communicate over standard protocols such as SPI, UART and I2C. This makes integrating a wireless module as easy as a digital component. Pre-certification helps prevent you from going through the certification process on your own, which can be expensive and time-consuming.
Easing the Design Process
Microchip’s AVR-BLE and PIC-BLE development boards are examples of streamlined development tools for IoT and other connected applications. These boards are preconfigured to transfer accelerometer and temperature data and integrate with a custom interface in the LightBlue® Explorer app. With widespread compatibility to consumer devices such as smart phones, which also can be configured as a gateway to the internet, you can skip much of the nittygritty design work and get to what matters: innovating and taking your product to market faster.
Through user-friendly, pre-configured tools such as the AVR- and PIC-BLE, building a connected device has never been more approachable. Whether you’re an embedded designer by profession, a maker or just a curious electronics hobbyist, you’re capable of building a robust, multi-faceted IoT system. This powerful accessibility, coupled with an increasingly connected world, ensures that connectivity will continue to drive progress in an unprecedented way.