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Comparing Cellular Hardware

/ Written By Chris Gammell

TL; DR: We created a shared document that compares a wide range of cellular hardware (including our own). Use it to evaluate what is available in the marketplace to get your project started quickly.

In my group at Hologram (Developer Relations), we need to work with a lot of hardware. In fact, the entire company is dedicated to working with the broadest range of cellular hardware possible. And there is a lot out there.

Even more hardware is on the way. If you’re not watching the news around the cellular industry like we do, there are a wide range of new modems and modules on the way. These will allow people to access new 4G LTE Cat M1 and NB-IoT offerings from cellular carriers. We’ll surely be writing and talking about that more in the near future.

Staying on top of things

When you’re starting a new cellular project, you have a lot to consider: Which modem should you use? What is your price point? Will you use an add-on module or roll your own? Will there be software available? Which networks and countries will be supported? The list goes on and on.

Our own list

We did what engineers do when things get confusing: we made a spreadsheet.

This one is on GitHub as a CSV. That means it’s shareable, extensible and also our community members can contribute to it with a Pull Request (PR). In fact, we’d love for this to not only be a community resource when starting projects, but also as a way to track any new hardware you’re creating with cellular capabilities.

Our goal is to get you and your project/product online quickly. Starting from a good place in terms of hardware and software resources can really speed that up.

https://github.com/HologramEducation/cellular-board-tracker

A work in progress

“The perfect is the enemy of the good”

If you clicked the link above, you notice there are still gaps. Not just some info yet to be completed, but also some categories of hardware completely left off. We wanted to cover many of the developer boards and platforms we see on a regular basis. We’ll see lots of new hardware in the coming days and we will try to add it as soon as we can. We’ll also update people on our developer mailing list whenever we add new boards (sign up here).

Noticeably absent from the list are things like gateways, wifi hotspots, end user devices and low level modules (the kind that we solder onto our own boards, as do other hardware makers). The crossover point between cellular hardware purpose made for Internet of Things (IoT) platforms and consumer platforms is a fuzzy line. We’re starting with hardware that is targeted at people putting devices out into the field. Really we’re covering the hardware we have seen on our Community forum and asked about by Hologram users.

“Where is my favorite module?”

We know some of you reading our list are fuming that we forgot about your favorite piece of hardware. We won’t even offer an excuse, it’s likely we forgot something! We are happily encouraging Pull Requests to this list and would love to add the hardware you know about. We’re also always on the lookout for people creating libraries to talk to cellular hardware, like the SIMCOM library written by our own Benstr. These community resources help new engineers get online faster and that’s a good thing! Finally, if you’re building your own hardware, we want to know about it and help promote it via our social channels and on this listing. There is a lot of room in the world for more cellular hardware and we want to make sure it’s on our list.

What is our criteria?

We make no judgement on anyone’s hardware, we’re just trying to compare and contrast the different features. This will ultimately help you find the right hardware for your application. So let’s take a look at some of the things we have on our list right now.

Manufacturer / model name

This is the most basic info about a particular piece of hardware. We think the manufacturer is particularly important. While we help people get new hardware online, it’s important to know that we can only troubleshoot a piece of hardware up until a point. Most hardware will immediately start working when you plug in one of our SIM cards; in the event it doesn’t and you work with us to troubleshoot any of the normal things (setting the APN, checking the SIM card is registered), you may need to work with the manufacturer. We’ll happily work with them as well to ensure their hardware connects to our network. Early access hardware does have the possibility of hardware and software bugs, so we want to point out that the manufacturer should be involved in the troubleshooting discussion.

Category

Understanding the target market of each hardware/platform determines the fit for your application. For instance, if you’re making 1 million devices, it’s unlikely you’ll want to design in an add-on module, such as an Arduino shield (or use an Arduino at all, for that matter). At that volume, you will want to develop your own hardware to lower your material costs and move to a bespoke solution. Similarly, if you’re prototyping for a customer demo, it’s unlikely you want to build something from scratch, just to get something out the door. Here are the categories we started with:

  • Add-on Module
    • These devices plug into other development boards, normally through header pins or connectors. It cannot operate on its own and requires an external processor and software library to send messages over cellular.
  • Embedded Board
    • This is a device that can operate standalone. You write code for this device and it has pins you can interface to. Our own example of this is the Hologram Dash; you write code that runs directly on the user processor and can easily pass messages through the onboard uBlox modem.
  • Integrated Module
    • This is a newer class of development platform. It allows you to interface directly to the cellular modem, but is targeted at putting a device into production.
  • USB Modem
    • This kind of device adds cellular connectivity as an abstracted element in linux systems. Our own Hologram Nova does this and paired with our Python SDK makes it a great addition to Single Board Computers (SBC) like the Raspberry Pi or the BeagleBone Black.

Lifecycle status

Hardware has a shelf life. Even when a piece of hardware still works on our network, the manufacturer might decide to stop making or supporting devices. It’s important to understand this before you start designing a piece of hardware into a product you expect to last for many years. We’ll note this as Active, Sampling (not yet released) and Obsolete.

Retail cost

This is where a comparison list is most useful to people getting started. If you’re just making a one-off project, having a somewhat expensive add-on board isn’t a big problem. If you’re looking to manufacture thousands, those costs will start to impact your bottom line.

Link to the product

We link to the manufacturer site for each product. Purchasing the device may require you to click through to a distributor. We want to link to the manufacturer so you know where to find support around that particular piece of hardware and in the event the distribution changes over time (most of these pages have a “where to buy” section). If you can’t find the board anywhere for sale, please submit a PR so we can keep up to date on the availability of each platform (and investigate if the board has gone obsolete).

Modem manufacturer and name

We list the modem manufacturer to show that there is a limited variety of cellular modems in use on most development boards in the marketplace. Some of this is tied to the technology, such as the new LTE Cat M1 hardware. You’ll note there are few modems that can access this part of the spectrum (though our SIM allows these modems onto the network where available).

The benefit of seeing which manufacturers use which modems is the software and libraries are portable from one device to another. It also shows popular modem types, which might inform your hardware design decisions.

Coverage (carriers and countries)

The coverage type has an impact on transmit speeds, power draw, product longevity and more. We label these generally as 2G, 3G, 4G LTE Cat M1 and NB-IoT, but there are many more individual classifications. Modems and dev boards specific cellular bands they can connect to. This determines which countries and individual cellular carriers allow the device onto their network. We categorize the technology and region at a high level so that you can make a decision based on where you are and what you want your product to do.

We also call out integrated GPS, as many people need more precise location than tower triangulation can provide. The tradeoff is the added cost and power draw of having a GPS on board. Sometimes this is built into the modem and sometimes it is on the PCB as a separate module.

Tested/working with Hologram

Most hardware will immediately start working when you plug in one of our SIM cards into the slot. That is a nice platitude, but our users want to know if we have actually done it. Again, this help you to make a decision about which piece of hardware you will use, especially if you are already deciding to use our network. We aim to cover the widest amount of hardware in the industry and continue testing hardware at our facilities over time.

This is another area where we’d love to hear from our community. If you have tested a new piece of hardware on our network or are in the process of testing a new piece of hardware we’d love to support your efforts and also showcase them to the rest of the community. It might seem like a small step, but building a broader base of community knowledge will enable faster decision making.

We will mark these as either:

  • Y – Tested and verified works
  • N – Tested and verified does not work
  • ? – Not yet tested
  • N/A – Not able to get onto our network

SDK / libraries available

Few people want to write a library from scratch. It takes a long time, requires low level knowledge of the modem protocol/commands and requires much more support over the long term. As such, we note whether or not there are existing libraries for a piece of hardware (and where they are located). This should also help you decide about which piece of hardware is right for your application because of how much community/vendor support there is for a particular device.

Power

Cellular is not known for being low power. The transmit power on GSM devices specifically has a large current draw, though usually for a very brief duration. This impacts battery powered devices the most, but can also impact other parts of your product, such as heat sinks, power supplies and supporting hardware. We’ll attempt to standardize and characterize this for hardware. Then you can make a better determination of which hardware fits into your final product. It’s likely this will be directly tied to the modem type/manufacturer, since the cellular portion of the circuit will take the most power; but understanding the overall power draw is important, in the event support circuit takes additional and unexpected power.

Features

This is the “everything else” of this list for now. What other features are characteristic of the board in question? We’ll use this are to call out if there are particularly interesting features the total solution space of cellular hardware, there will be a large variety in other services are provided by each piece of hardware.

More to come

This is far from an exhaustive list of all the things we expect our users to want to compare and contrast. For now, it represents hardware being used every day by our community members.

Some comparison categories will take more time to evaluate. Things like power draw of devices will require testing at our facilities so that we have similar setup for each test. We’ll note when our community members help contribute their experience and appreciate when they take the time to help out. Remember you can contribute by submitting a pull request.

If you have any questions about this list, give us a shout over on the Hologram Community Forums!