Electrical Documentation

Introduction

While it's generally accepted that electrical documentation is important, it's not intuitive what exactly needs to be documented in every case. A good list of documents that is sufficient for research work in the Robolab is that for every circuit you create, you need power and data diagrams, a power usage table, and a bill of materials.

Power & Data Diagrams

Power and data diagrams are more specific versions of wiring diagrams. If you are making a board-size circuit on a breadboard or protoboard, odds are that you can combine the two. If you are laying out a larger circuit such as the internal wiring of a robot, you will need separate power and data diagrams for cleanliness and debugging. Fritzing (link) is a free, open-source tool for both levels of diagramming, and can be installed in Ubuntu. Power diagrams should have wire labeled based on voltage level, while data diagrams should have wires labeled based on type of communication. Both types of diagrams should have wires colored the same way that they would be in real life, to simplify debugging. Indicating connectors on these diagrams is also helpful.

Power Usage Table

When you are doing wiring design using multiple components, each component has some current usage, usually measured in mAh. Adding up the mAh of all the components and comparing it the capacity of your battery should give you an approximate battery life for your system.

Bill of Materials

A bill of materials (BOM) serves the dual purposes of being both a list of components and an overall pricing chart. Your BOM should list each part you bought and each raw material you purchased along with prices, quantities, and location/website purchased or obtained. Someone looking to duplicate your circuit should be able to use your BOM as a shopping list. For professional BOM advice, see the Helpful Links section.

Helpful Links

• Bunny Studios: How to Make a BOM (link)
• Proto2Prod: Creating and Optimizing a Bill of Materials (link)
• Fritzing: Make your own Fritzing Parts (link)