The basic design process is very similar for any product whether it be hardware or software and breaks down into a series of well defined stages as shown in the diagram below. It is also extremely important to separate the ‘what is my item going to do’ and ‘how is it going to do it’ from each other.

If you define the ‘what’ part properly, the ‘how’ part follows more easily.

The worst way to start the process is reaching for the soldering iron / drill / keyboard and saying “I’ll now make something”. My favourite tools at the start of the process are a pile of scrap paper, a pencil and eraser - the more time spent in the early stages, the less time will be spent during the prototype build and tests stages when making changes takes longer and costs much more.

You may find that when you have finished a particular step, it is necessary to revisit a previous step to make some minor changes - this is perfectly normal. At the paper design stage this is quick and easy to do. At the construction stage it is much more expensive and time consuming so do as much thinking and planning as you can at the paper stage. When you have completed the paper design go back and check each step. Get a colleague to do a peer review as well.

Each module in the final product should be treated as a ‘black box’ with a functional specification and a defined list of interfaces to other modules - this is the “what it does” part. How it does it is another issue entirely and down to the individual module designer. Modules may share some common requirements like temperature, humidity, supply voltage etc.

Other factors in your design are the quantity of the product that that you intend to make, its working environment and its projected life span. High volume brings its own set of requirements, long life span means looking at long term availability of components for both manufacturing and maintenance spares and difficult environments like high or low temperature, vibration etc directly affect the components and mechanics.

On completion of step 6 for a high volume product you will probably make a small pre-production batch to test the repeatability of the design and the results from this may require that you revisit one or more of the specification and design steps to correct an anomaly (or error!).

Looks easy, sounds obvious? Well, if you do your planning and design properly it is a lot easier than if you don’t! There are a number of different methodologies that you can follow for various types of design task from hardware to software but they are all based on correctly defining what you are trying to achieve, dividing the whole into a number of cost effective parts and documenting each part.

This is a very high level view of the overall process and does not address the detail required in say a receiver or transmitter design. It is intended as a guide to help you to achieve your desired results with the minimum time and costs. Always remember - Keep It Simple because Simple = Lower Cost and Time (and less stress on you). ‘Simple’ means do not over-complicate it where it is not necessary.