Wearable LED Matrix Display Badge

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Introduction: Wearable LED Matrix Display Badge

Are you running an event ,competition or even hosting a birthday party ?

Badges are versatile item that can make introductions and celebrations that much easier .You would never begin a conversation with "hello , my name is ............." so why should your badge?

So lets design a PCB Badge that you can pin proudly and wear at your next important event.

In this project, I will be showing how I built a badge-sized ATtiny85-based LED matrix display (5x4 matrix). I have used Charliplexing technique for driving 20 LEDs using ATtiny85.

you can even easily add extra texts to your badge as you wish.Standout from the crowd with this awesome PCB badge.

Lets get started :)

Step 1: Watch the Video

The video goes through the build process as well, if you prefer to learn that way!

Step 2: Things Used in This Project

Hardware components

  • Microchip ATtiny85 x1
  • Coin Cell Battery CR2032 x1
  • 3 mm LED x20
  • CR2032 Coin Cell Holder x1

  • 8 pin DIP IC Socket x1

  • Slide Switch x1

  • Resistor 100 ohm x5

To program ATtiny85 you need an arduino uno or any other arduino boards.

Software apps:

  • Arduino IDE

Hand tools:

  • Soldering iron

Step 3: Charlieplexing

Charliplexing is a technique for driving a multiplexed display in which relatively few I/O pins on a microcontroller are used, e.g. to drive an array of LEDS. The method uses the tri-state logic capabilities of microcontroller in order to gain efficiency over traditional multiplexing.

The formula for Charlieplexing isLEDs = n^2 - n

where 'n' is the number of pins used.

I use an ATtiny85 programmed with the arduino as ISP.So it uses 5 pins for 20 LEDs.

More info on Charlieplexing: http://en.wikipedia.org/wiki/Charlieplexing

Step 4: Schematic Diagram

Step 5: The Prototype!

Before designing a PCB, I decided to build a prototype on a perfboard.

And it worked fine......

Step 6: PCB Design

I used KiCad for PCB Design.The edge cut were made using .DXF file which was designed and generated using Autodesk Fusion 360.

The size of PCB badge was 55*86 mm.

I quoted and ordered PCB through PCBWay.com.

Note:
The White Silk Screen On the center is provided to Write your Name or Whatever you want :)

After soldering the PCB looks like this:

This project is open source. If you would like to build your own, all of the resources are available in the my GitHub page.

Step 7: Wire the Circuit to Flash ATtiny

(DON'T insert the battery now.)

On the PCB I have provided 6 pin connector for programming ATtiny85.the small dot near the 6-pin connector is the first pin (MISO), see the photos for alternative connections.

  • Arduino +5V ---> VCC
  • Arduino GND --->GND
  • Arduino pin 10 --->RST
  • Arduino pin 11 --->MOSI
  • Arduino pin 12 --->MISO
  • Arduino pin 13 --->SCK

Follow the below link for programming ATtiny:

The Instructables Community Manager randofo had written a nice instructables on "Program an ATtiny With Arduino".

you can download all source files from my githhub page:https://github.com/amalmathewtech/ATtiny_LED_Matrix_Display_Badge

After Configuring Arduino IDE Tools Menu, upload given arduino sketch

Note: update 11th line of arduino sketch to display as your wish

Step 8: Sneak Peek Video

Have fun :)

Thank you so much for reading if you need any more information feel free to ask in comments, and I'll do my best answer you.

If you like this project you can support my project by Voting it for Party Challenge .

You can also support my project on PCBWAY's I can Solder KIT 2019 contest

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Happy making! :)

Party Challenge

Participated in the
Party Challenge

1 Person Made This Project!

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18 Comments

0
tehhustler
tehhustler

Question 2 years ago

How are you getting g 5V out of a CR2032?

0
tehhustler
tehhustler

Answer 2 years ago

Wait, does it just pull 3V? Is that why your LED resistors are so low?

0
Bigbadhodad1
Bigbadhodad1

2 years ago

I’m building it but will be substituting a arduino pro mini and I’m not sure about the pin changes, I got MOS1 as pin 8 MOS0 as pin 9 SCK as pin 13 PB3 as pin 11 and PB4 as pin 12 am I correct?

0
Bigbadhodad1
Bigbadhodad1

Reply 2 years ago

I built it but it doesn’t work

image.jpg
1
AmalMathew
AmalMathew

Reply 2 years ago

Did you modify code according to pro mini .

0
Bigbadhodad1
Bigbadhodad1

Reply 2 years ago

I thought I did, though I’m still learning it. Do you by any chance have the code for it?

0
mohir
mohir

Question 3 years ago

When inserting the LEDs where should the plus side be on the square or in the circle?
Please reply :)

0
KarloHorcicka
KarloHorcicka

Answer 3 years ago

I believe that the square is for positive lead

0
mohir
mohir

Reply 3 years ago

Thank you for replying, I hadn't the patience and tried put the other way around (Square as negative) and it works well, i saw that the square on the battery holder is connected to the Ground on the attiny. The strange thing is that before soldering entered the Leds the other way around and they still lit up...

0
AmalMathew
AmalMathew

Reply 3 years ago

Yeah, it works if you insert it in other way too. You just read about charliplexing ,they you will have idea that why it works on both methods .

0
mohir
mohir

Question 3 years ago on Step 8

on the pcb the squares are the plus or the minus side?
thank you

0
AmalMathew
AmalMathew

Answer 3 years ago

Here the square one is cathode(-ve).

usually square will be used as anode (+).

0
mohir
mohir

3 years ago

Very nice idea!!!! Thank you for sharing,
As they are many types of CR2032 Coin Cell Holder and of switches, could you please give a link to ones that fit your PCB.
Also tried to order the pcbs but it doesn't allow me to checkout :(

0
Arbormakes
Arbormakes

3 years ago

Amazing!

How much does it cost to order the PCBs?

0
jessyratfink
jessyratfink

3 years ago

That's a pretty neat idea. Definitely more fun than a standard name tag :)

0
AmalMathew
AmalMathew

Reply 3 years ago

Thank you :)