Cellular Connectivity for IoT in the USA
In March of 2014, I ran across a post by @stavros titled Arduino-powered irrigation system. I was extremely excited to tell my father-in-law (Pop) about it and how I thought I could build him one out and get it to him by the watering season. What started out as a fun side project turned into a 2+ year journey that has now culminated into an ongoing Kickstarter campaign.
What was so cool about @stavros implementation was that is was 1) cheap, and 2) used text messages. Pop wouldn’t have to learn anything new, and I would not be required to write a mobile application or some sort of web interface.
What I didn’t know was that the cellular market here in the USA is vastly different than that in Europe. Here’s why:
Europe is still supporting 2G. While 2G & 3G Shields were available from China, regular US data plans are expensive. “Cheaper” M2M data plans exist in the US, but the arduino shields were not allowed on the larger networks like AT&T and Verizon because they had not been through the (expensive) certification process <-- more on this below. The smaller networks, TMobile & Sprint, would turn a blind eye to these products on their network, but their signal strength out on the farm was non existent.
Signal strength was a big problem. 2G GSM is going away in the USA. It is set to “sunset” in 2017. There is such little support for 2G that when I tried to use the Arduino shield @stavros implementation using TMobile, it would work in the city but there was zero connectivity out on the farm. In fact, I had the same experience with 3G as well. I even ran a 20 foot SMA coax cable up the telephone pole near by with a 3G antenna on top tied into the ElecFreaks 3G Arduino shield and still had zero connectivity.
USA certified devices - especially 4G - are practically non-existant. Still to date, I know of only one Arduino shield that is. I moved over to Single Board computers like the Pi & Beaglebone Black in order to use a 4G cellular modem. I found the ConnectedIO LT1001 4G modem and I had high hopes of doing the trick; however, I found out quickly that it wasn’t provisioned for SMS. Basically, during the certification process, one has to choose all the features of the device that it is going to support. During the certification process, this device was not chosen to support text messages. Additionally it would only connect to things via USB - which meant I could only use a single board computer over TCP/IP. Keeping my hopes up, I implemented a solution to use this device, but soon because aware that the M2M data plans were going to eat my lunch. Additionally, the USB connection proved to be a problem on the Beaglebone Black. If USB connection went stale in any way, I had to have massive error correction code that would reboot the USB subsystem on the BeagleBone and subsequently the device itself if it still couldn't talk. There were cases where even after a reboot, I was still unable to connect. This was not cool.
Ethernet to Cellular routers are still expensive. I decided to start trying to use a cellular to ethernet router; however, at the time, the cheapest device available was around $400. This just wasn’t an option as Pop has over 40 wells. Costs were starting to climb 5X from the original idea.
M2M is still in it’s infancy. I started calling solution architects from Verizon and AT&T begging them to find a device that would enable me to connect Arduino’s or Raspberry Pi’s over the 4G network. AT&T wasn’t interested in helping. Verizon went on an hunt for me, but came up short. I quickly learned that the big carriers have a rigorous certification and approval process for electronics that want to use their network - a cost of anywhere from $43,000 to $75,000 AFTER the module has been certified. See, first the cellular module has to be certified and approved - a cost of up to $200,000. THEN each physical implementation of the module has to be approved. The carriers do this because they are heavily concerned in the US with quality of service. If they don’t control the physical implementation of each device, they can’t guarantee that the device will talk nicely to the cellular towers. If they have a rogue device on the network that decides it wants to be chatty and / or go crazy in trying to connect, it could bump everyone else off the tower which amounts to really angry customers.
So finally, after 7 long months of massive research and prototyping, and as a last resort, I went to a local Maker-Space meeting in Plano, TX and made a plea for help. I really just wanted to know if I was missing something. That’s where I met Don. Don is what I call an Electrical Ninjaneer. He’s a genius when it comes to small electronics and radios. He had a hard time believing there was no legitimate way to do this in the United States. So we made an agreement that if my story lined up with the Verizon Solution architects story, he’d help me out. We ended up creating M2M Circuits, Inc. and developed the first 4G modem designed to allow the maker space to connect their small electronics to the Internet using TCP/IP OR SMS. We call it the MakerModem.
In getting to design this new device with Don, I asked him to fix some of the other irritating issues I had encountered along the way:
I wanted internal antennas because it’s just ridiculous to buy a device and then have to pay an extra $40 for antennas. But, if I have to put this in a metal box, I wanted the option to use external antennas too. So Don put in U.fl connectors to accommodate either an external OR internal antenna system. Sweet. Additionally, he designed in this really cool ability to switch between these two antenna systems on the fly programmatically through a micro-controller or single board computer if you have both connected.
I’m not an electrical engineer - and so when someone tells me that I have to “level-shift” between my computer or micro controller in order to talk to a device, I just get irritated. All I can think about are breadboards and wires all over the place. I wanted to direct connect whatever device I wanted to this thing. So Don put in a really cool voltage control pin that the SBC or micro controller can tell our MakerModem what voltage to talk on. Cool stinking stuff.
Sometimes I could tell that there was power to the devices, but couldn’t tell by looking at it that there was actually network connectivity too. So, Don put in two lights: one for power, and one for network. Now it’s easy to tell the issue, without having to get on the device and poke around.
I wanted to be able to choose what network we used. We did a massive search across several cellular modules, and finally found a company that could give us exactly what we needed: a serial interface + ability to work on Verizon or AT&T. The U-Blox L201 module does just that. We now have the ability to switch between Verizon and AT&T with just a SIM card. While the module works on both 4G networks, it also works on AT&T’s 3G networks as well. We’re told that this same module will support networks in Canada and Mexico too. Moreover, while we haven't prototyped or tested yet, we believe we can simply swap out our module with a European cellular module - like the Toby L210 - and support that maket as well. We hope we can make enough off our Kickstarter campaign to do just that!
Finally, Don built in a place to support a GPS module in hopes that a future firmware upgrade will enable us provide GPS as well.
After we finally got our MakerModem ready to go, we wanted to show it off some how. We engaged some brilliant young minds at a major university in Dallas, Texas, and asked them to create a demonstration platform that would show off the MakerModem’s 4G LTE connectivity. We were stoked to see what came out of this. First, we asked them to first abstract the AT cellular command set to create a open-source API making it easier for people to connect their devices on 4G. They worked hard in the fall semester of 2015 to do just that. The API is functional and available for use! This API was designed to work with both micro controllers and linux based platforms. We even had one of the team members port it over to Windows. Secondly, we have a team working now to use both the API and the MakerModem to fly a drone over the 4G Cellular network! They call it the “SuperDrone” and we can’t wait to see this thing in action! The team will be using both TCP/IP and SMS to perform different functions.
So - after all the hard work, I’ve had the pleasure of learning a ton from Pop, @stavros, the cellular networks, Don, U-Blox, the MakerSpaces, and the students at UTD. A super super special thanks to Grandma who has been such an encouragement and help in so many ways. Love you Grandma!
It’s been a long journey, but we’re hoping we can get enough funding to continue on. Check us out at m2mcircuits.com or https://www.kickstarter.com/projects/makermodem/maker-modem