When designing any product, the first steps are to identify the need the product will fill, and identify the market it will be sold into. Then we consider the competing products that can already perform the job - even 'unique' products have some kind of competition, somewhere. Finally we build up a specification for a new product positioned successfully in the market. This is detailed a little more in our guide to writing a new product spec.

This guide describes our process for designing a new electronic circuit board, typically one that is microprocessor based with embedded firmware. This same process is used for most products we design. Usually an industrial designer is employed to produce the product enclosure or case, with labelling and graphics. We deliver working prototypes and technical documentation to the client - and then the product goes on to beta testing, pilot run, and production release.

Nothing is particularly hard if you divide it into small jobs. --Henry Ford

The Specification

The Specification is the customer's instructions to the designer describing the features the new product should have. (See: More info - Specifications) A specification starts out as ideas and a wish list, then gradually gets nailed down to something more formal and explicit. It is a good idea to have a list of "reasons why" and "how it's done" to explain the specification, but keep these separate from the main document. We have, online, a guide to writing a specification for a new electronic product, help with specification construction, examples of specifications, and a glossary of technical information.

The basic, introduction explanation of the products function within a specification should be quite short, keep it to one page:

The Circuit Design

The Circuit Diagram, also called the Schematic or Logic Diagram, maps out the electronics and connections in the most readily readable form. (See: More info - Circuit Design) The designer needs to do background work while producing the Circuit diagram, researching specifications of components, interaction between components (especially timing and loading) physical packages, and arrangement of connector pinouts. The circuit will often start on paper and finish in Computer Aided Design (CAD) format.

The finished circuit diagram, supported by notes if required, is the main reference document for the design.

The Printed Circuit Board Layout

The Printed Circuit Board (PCB) is the laminate to which all the electronic components are soldered, with one or more layers of etched metal tracks making the connections. (See: More info - PCB Layout) The components and connections in the PCB Layout are derived from the circuit diagram, and physically placed and routed by the designer to get the best result. The PCB Layout defines the final physical form of the circuit, and enclosure and labelling details can be finalised as the layout is completed.

When the PCB layout is complete, the final CAD file is sent to a subcontract PCB laminate manufacturer. (for detail on PCB laminate production see More info - PCB Etching) The manufacturer returns the etched PCB laminates a few days later, ready for assembly into prototypes.

Prototypes

At AirBorn Electronics we usually make 2 or 3 identical prototypes at the same time. (See: More info - Prototypes) The Prototype circuitry is debugged in stages. The debugging proceeds according to the debug test procedure, which is written for the product as it is designed. Prototype microprocessor circuits are generally debugged with specially written diagnostic code, again progressing in stages.

When confidence has been gained in the operation of the prototype hardware, debug of the actual prototype program ("Firmware") can begin, on the target.