This article explores the pros and cons of connectivity options for IoT edge device design, discussing the importance of putting the I in IoT.

If you’re reading this article online, odds are you are connected over cellular, Wi-Fi, or Ethernet. While these connectivity methods are widespread in consumer electronics, Internet of Things (IoT) edge nodes aren’t as tied to them. Unlike consumers, most edge devices do not check email (lucky them) or indulge in streaming movies, so they do not require the high data rates used in consumer electronics.

IoT solutions often consist of hundreds, or thousands, of connected edge devices. Typical design constraints, such as cost and power management, become magnified as more edge devices are added. At that scale, the way your product connects to the internet can determine whether it succeeds or fails.

 

The Internet of Things (IoT) is made up of up of hundreds, or thousands, of devices connected to the same network

Figure 1. The Internet of Things (IoT) is made up of up of hundreds, or thousands, of devices connected to the same 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.

Because Ethernet is hardwired, it is also inherently a very secure connectivity method. There is also the capability to power your device through the Ethernet cable through Power Over Ethernet (PoE), which eliminates the need for a separate power module.

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. In modern buildings, automated lighting systems are hardwired during construction, but installing an Ethernet IoT system in a building not designed for it is often not feasible. 

 

Wi-Fi

As the go-to for internet connection, the wireless nature of Wi-Fi is incredibly appealing. It is widely supported by mainstream devices and does not contain the hardwiring constraints of Ethernet.

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. 

 

A favored internet connection option in consumer electronics, Wi-Fi brings the benefits of high-speeds and wireless connection

Figure 2. A favored internet connection option in consumer electronics, Wi-Fi brings the benefits of high-speeds and wireless connection.

 

Luckily, solutions exist today to help engineers overcome these barriers. Using a Wi-Fi module that has been optimized for IoT will simplify your design and save development time. Modules like the WINC1500 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. A significant portion of IoT applications are in wide-area applications, 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 Mojave Desert. 

 

Agriculture is a perfect application of LPWANs because these networks can cover large swaths of area with very little power

Figure 3. Agriculture is a perfect application of LPWANs because these networks can cover large swaths of area with very little power.

 

Ranges in typical LPWAN use appear 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-it-yourself” network, but most still opt to use a local network provider’s LoRa gateway infrastructure and pay a per-usage fee.  

 

Cellular

Aside from extremely rural and remote areas, cellular coverage blankets 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 your cell bill might be substantial, a CAT-M plan runs around $7/month for 5 MB of data. Other options for cellular IoT connections are CAT-0, CAT-1 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®.  

 

While satellite is beneficial for remote areas of the world that are not covered by cell service, options are currently limited for commercial IoT use

Figure 4. While satellite is beneficial for remote areas of the world that are not covered by cell service, options are currently limited for commercial IoT use.

 

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 5.0 is a recent update that extends Bluetooth’s range so that it can be used in home area networking. Whereas Bluetooth Classic and Bluetooth LE are typically used to connect devices that are mere meters apart, you can connect an entire home with Bluetooth 5.0. 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. Commonly used networks, such as Wi-Fi and Bluetooth, are often the easiest way to evaluate and explore IoT designs. These networks do not require you to build your own gateway or pay for a provider.

Several Wi-Fi and Bluetooth prototyping modules are available to consumers, and many come with open source code and tutorials on how to program them. Using connectivity modules is recommended because it makes the design more flexible. When it comes time to adapt your design for a different network, you can swap out the module instead of starting from scratch. 

 

Easing the Design Process

Connecting to the internet is just one component of IoT design. IoT systems should check three boxes: smart, connected and secure.

This translates to three electrical components: a microcontroller (MCU), a connection module and a secure element. The challenge of IoT design comes from the integration of these three components.  

Microchip’s AVR-IoT WG development board is an example of a streamlined Wi-Fi development platform. The board is preconfigured to securely connect to Google Cloud’s IoT platform. With a secure element, Wi-Fi controller and an MCU all on one board, you can skip much of the nitty-gritty design work and get to what matters: innovating and taking your IoT product to market faster.

 

The AVR-IoT WG development board is pre-configured to securely connect to Google Cloud

Figure 5. The AVR-IoT WG development board is pre-configured to securely connect to Google Cloud.

 

The Arduino Uno WiFi Rev 2 also offers smart, connected and secure elements. Arduino hosts an active prototyping community with many tutorials and open source code available online.

MikroElektronika click boards™ are rapid-prototyping modules that connect directly to the AVR-IoT WG development board, or through a shield for the Arduino Uno WiFi Rev 2. With several connectivity click boards available, including a variety of LoRa and Bluetooth modules, these boards offer a great way to add connectivity to your IoT design during the prototyping phase. 

 

The MikroElektronika BLE2 click board integrates easily into many general-purpose development platforms

Figure 6. The MikroElektronika BLE2 click board integrates easily into many general-purpose development platforms.

 

Through user-friendly tools such as Arduino and the AVR-IoT WG development board, building an IoT device has never been more approachable. Whether you’re an embedded designer by profession, a maker or just a devoutly curious electronics blog follower, you’re capable of building an IoT network. This powerful accessibility, coupled with an increasingly connected world, ensures that connectivity will continue to drive progress in an unprecedented way.

 


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