Learning PCB design in one week

Since the day that I was able to take apart my first toy, I have always wanted to fabricate my own PCB.

That long time dream finally came true when I decided I would tackle the challenge for the Robot Eraser  project. Read that article first if you want to understand the project a bit better.

The objective of this PCB was to combine two power sources in order to power the Atmega chip. One power source is a DC solar panel and the other is an AC shake linear generator. Together they will power a robot which erases a dry erase whiteboard. Additionally the circuit features a programming bus on the left most section where I am able to connect an FTDI programmer.

You may recognize that this schematic is very similar to a lillypad Arduino. That is because it is based on lillypad. The only difference between my PCB and a lillypad is the power circuit which combine the two sources of energy and the transistors to power two DC motors.

So how did I build it? Never having done PCB design I was able to quickly design and fabricate this board on my own. The first step was researching. I discovered a brilliant design called Ardweeny which inspired this board.

Ardweeny was designed to be the smallest possible Arduino with a through hole chip. The schematic is identical to a lillypad and is programmed in the same manner. Because the Robot Erasor was weight sensitive I decided to take this minimal approach with my own board. The source Altium files are provided by SolarRobotics for free. This meant that I was able to examine their schematic and design as I learned to make a PCB.

Before making a PCB one must decide which software to use. Eagle is very popular at my university and is very good for being free. Right off the bat I started with Eagle and became frustrated with Gerber export. Ultimately I decided to try Altium.

I downloaded a one month trial of Altium and it is a wonderful program. Because most professional designers prefer Altium, most open source PCB designs are in Altium file formats. Just download and then you can start to modify. I used this series of tutorials to learn Altium.

I downloaded the Ardweeny source Altium files and added my schematic components. I was having issues finding exact sizes for some of the components that I was placing so I worked around this by just inserting them as headers on the schematic.

Both monitors of Altium. Schematic on Left. Complete board on right
Once the schematic was done you can create a PCB and an interface shows a rats nest of components. I didn't bother to manually route as this board was very simple. Auto route and verified.

Some observations are that I did not make the holes on the four corners large enough to be useful. Also, LED2 is too close to Rst and both cannot fit.

After exporting the Gerber files I uploaded them to OSHpark where I was able to print three copies for $10! Free shipping and two week turnaround.

And that was it. The process is very simple once you get past the learning curve of the software. I look forward to designing many more boards soon to come.