LED Matrix PCB Design

Today I shipped off my LED Matrix design for fabrication!

The layers of the LED Matrix printed circuit board.

The LED Matrix is a 4 by 5 matrix of LEDs that will blink out messages or the time or something.  I was inspired by the Wayne & Layne design and decided to give a try myself.

More after the cut.

Schematic for the LEDMatrix

Schematic for the LEDMatrix showing the 4x5 LED matrix.

The circuit is a very simple charlieplexed design that will work well with the ATTiny25 microcontroller I chose for this project.  The only other components in the circuit are an ISP header, a reset push-button, and a CR2032 battery holder for power after programming is complete.

This will be my first surface mount project.  I chose 1203 sized components because they are large. For solder paste I bought whatever was available from Digikey in a relatively small package.  There was a choice between leaded and non-leaded: I went with the leaded.  Matt suggests trying the hot-plate method but says an iron and some solder wick will probably also work.  Digikey also had tweezers so I got a cheap pair of those also.

LED Matrix PCB top copper layer from Circuit People Gerber viewer.

As this was my first circuit board, this was also my first interaction with Gerber files. Being too lazy to find a Gerber viewing package for mac, I used the CircuitPeople Gerber viewing package. It worked well enough for my purposes but I had trouble printing to scale using the PNG files it outputs.

I am using the DorkbotPDX fabrication service for my design.  The price is relatively cheap at $5 per square inch.  Laen also provides detailed submission instructions and so far the process has been relatively painless.  The actual run goes out on the 21st, but the panels have been filling up early, so I put in my project early to assure myself a spot.

That’s all for now.  I’ll update more next month once the boards have come back from the fab.

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