Matrixtag

PCB layouting workshop

These are the example files and a short presentation for an introduction to printed circuit board layouting with KiCad.

The design is loosely based on Larry Ogrodnek's nametag, with some modifications and enhancements. There's both through-hole and SMD versions. The THT version is designed for 5mm LEDs, thus making it very large. A new 3mm version is being worked on.

The software for the microcontroller is in a separate project.

You can also find an example for a LED dot matrix display tag. (currently broken, the pinout is wrong)

Description

The circuit is grouped in 4 parts:

• 5 LED blocks
• Transistor drivers for each block (based on 2N7002 N-FETs)
• ATtiny13 microcontoller
• CR2032 battery

Each block consists of a total of 20 LEDs in parallel, which can be soldered on as desired.

It should be noted that the CR2032 has a high internal resistance and can only deliver small currents, up to about 40mA.

The current-limiting resistors for each block should thus be adjusted accordingly, to prevent brown-out of the MCU. Note that the transistors also have a relatively high on resistance.

If a Li-Ion or LiPo battery is used instead of the button cell, much higher currents are possible.

The parts are fairly standard and can be ordered from any supplier, such as Farnell, DigiKey, Reichelt, ...

License

This documentation is copyright © 2016 by Chaostreff Basel and describes Open Hardware and is licensed under the CERN OHL v. 1.2. Please see the the LICENSE file for applicable conditions.

The author's contact information can be found in AUTHORS.