From Prototype to Production

Here we will be exploring how to take your embedded system from a pen and paper design to a prototype and, eventually, to a product. In this step we will be looking at the end of that cycle: the final product.

Creating a Prototype

At some point, you may want to take your designs and make them into a physical device. You may even decide to turn that device into a product, to give or sell to others. If you want other people to be able to use the device without breaking it or having to reassemble it every time it gets knocked, you are going to need some sort of housing for the device to live in. You may also need to provide a way for the user to deploy the system, such as a wall mount or stand. All of these small changes and additions to make your device more usable take some thought and some work on the design to get them right.

Time for Production

Creating rigorous designs on paper is a great way to map out your thinking and to spot flaws or gaps that need fixing early on. Although you could iterate your designs infinitely, making small improvements each time, you have to decide at what point you are going to create something physical. This will be the best test for your designs, and they are bound to fail, but this gives you the chance to learn, and to iterate and improve. No amount of designing will remove all of the errors that will crop up when you first build. Better to fail now and fix the flaws than to find them when it is too late.

From Prototype to Product

The line between a prototype and a product is not always clear. Some products are obvious, like the phones we use every day. They have been packaged and housed in such a way that they are simple to use for their intended function.

When a user is holding a product, the inner workings are abstracted away and they see only the product’s functions. This is encouraged, not only through the appearance (there are no wires or exposed components as there are in a prototype), but also by the usability a housed product offers. A good product will provide clear indications as to how it is to be used, and by this we are talking about more than just labels. If the device is handheld, for example, ergonomic design can show a user how to hold it. If it requires mounting on a wall, the housing should show clearly which way it should be attached and how (with screw holes or hooks, for example).

Some embedded systems, such as smartwatches, are meant to be worn. The design of the housing should show the user both where to wear the watch and how it should be fastened.

Production

Any decisions about the outward appearance of your device should be focused both on the user and on the tasks your system is going to perform. These features can be treated just like any others. You can create a box diagram for them, and you should still be thinking in terms of features (what the device will achieve), tasks (how it will achieve it), and components (the tools it needs). The tools are the biggest difference when it comes to the fabrication stage, as you swap your code editor for design programs and your flow charts for diagrams.

Some of the possible methods and tools used in fabrication are:

• 3D printing
• Laser cutting
• Injection moulding
• Cardboard construction
• Carpentry

All of these can be used to create your housing, but some are more difficult than others and will require some learning to do them properly. This does not mean that they are out of reach, even for novices. There are plenty of services that will injection mould or 3D print something and ship it to you, so be sure to consider all of your options. We will explore some of these methods and tools in more detail later, but you should consider them as you go through the next few steps.

Production Method

The choice is really about two things: effectiveness and accessibility. If your design requires precise slots for your devices, 3D printing and injection moulding may be more effective than cardboard construction or laser cutting, depending on the layout. You should also consider whether you can access the equipment needed for that method. Finding the right balance between these two factors will help inform your choice.

Diagram Time

Consider one of the box diagrams you have been working on.

• How would you house that device?
• Add a design feature to the box diagram
• Map out the tasks and components you will need to achieve that feature