Turning your idea into a prototype

You have your idea…and it’s a really good one.  Now you need to build your prototype.  In this post I’ll talk about what’s involved in developing the prototype of a simple cellular M2M product.

Before you start, it is important realize that a cellular M2M product is not a product at all – it is a system.  A cellular M2M system is made up of:

  • The Hardware that gets deployed in the field.
  • Application Software running on the hardware – in the cellular M2M world we typically refer to it as just the application.
  • The Carrier, or airtime provider.  This can be a large carrier like Verizon or Sprint who own their own towers, or may be a Mobile Virtual Network Operator (MVNO) such as Telit, Jasper, Wyless, or Kore Telematics who resell airtime on other companies networks.  
  • The Server Side Application – this is where the database lives that holds all of your data and displays it on a cool webpage for your users.  The server application is broken up into several different pieces – accepting connections and data from the devices in the field, storing the data in a database, and presenting the data to your user base.

To get your prototype up and running you will need to do some work in each of these areas.  Let’s discuss them one by one.

Hardware  This is typically the first thing people think of when they have their idea.  “Dude!  Check this out!  We make a puck sized device that has GPS and a cellular modem and we sell it to parents so they can track their kids!”  So what does it take to get the hardware up and running?  First, don’t worry about the form factor.  Leave that for later and dazzle potential investors with powerpoint drawings for now.  Use development kits as much as possible – these are generic boards made by the manufacturer of your major components like the cell modem, processor, power supply IC, etc.  They are usually cheap and designed to be easy to use – some distributors even give them away for free.  Best of all they are designed to be wired into other development boards for just this purpose.  The two most important dev kits are for the modem and processor.  Make sure you choose these two parts carefully so that you do not have to change parts later on when you develop your first production hardware.  I cannot emphasize this point enough.  For the processor, make sure to think ahead and don’t change your hardware too much for your first design.  Mimic the interfaces used on the dev kits whenever possible in order to minimize the effort needed to port the application software.

Application Software  This will be running on your processor eval kit.  Don’t take short cuts – remember that the choices you make in designing the application will determine how easy it is to move from the dev kits to the production hardware when you do your first build.  Even though it doesn’t do much to dazzle potential investors, one of the first things you develop should be the boot-loader.  This is the piece of code that handles upgrading the application.  You will want to start testing this early so it is rock solid when you have to do your first Over The Air (OTA) application upgrade.  Also, count on things going wrong, not right.  Until you get some time under your belt working with the cellular network you will likely have a lot of dropped connections.  Handling this gracefully will only make your final product stronger.

Carrier  Decide on the carrier you want to use early.  Usually they will provide a couple of development lines that you can use with your modem demo boards.  Be aware that these accounts could get deactivated at any time.  It’s never too early to talk about the certification process with the carrier either.  Surprises and last minute scrambles during certification can be very expensive.

Server Side Application  Again, don’t worry about being flashy too much here, but don’t make an ugly duckling either.  This will likely be the most visible part of your product and therefor your pitch for seed money.  Many times the development team consists of a firmware engineer developing code for the device and one or more people focused on developing the server side application.  One of the best things you can do to get your device online and talking to the server quickly is to have a server side developer implement the application level protocol on both the device and the server.  Many times server application developers don’t want to work this close to the hardware, but having one person develop the protocol from both ends can save time and money.

Finally, plan on things going wrong not right.  Working with the cellular network is challenging because there is no one place to go to learn what you will be dealing with.  Be prepared to spend a lot of time working through issues with the carrier’s tech support team.  If something isn’t working right on your production hardware try to duplicate the issue on the development kit.  Many times small hardware quirks can manifest themselves in strange ways.  The dev kits can be a great tool to help isolate issues with production hardware as well.

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