Charlieplexing

Charlieplexing 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 microcontrollers in order to gain efficiency over traditional multiplexing. Although it is more efficient in its use of I/O, there are issues that cause it to be more complicated to design and render it impractical for larger displays. These issues include duty cycle, current requirements and the forward voltages of the LEDs.

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General Purpose Countdown Timer

“A general purpose countdown timer. Easily settable for up to one hour. Great for the kitchen. Perfect 5 minute eggs! In todays world of Apps for your smart phone, a countdown timer might seem like a bit of a redundant …

Animated Flame Pendant

“Turn on your heartlight Let it shine wherever you go Let it make a happy glow For all the world to see A little fire for your heart! But there’s no actual flame here, no heat…instead, LEDs and …

Development of ClockSquared Mini

“Summer break is here, and with some time to spare I decided to challenge myself with a project that I call “Clocksquared Mini”. It is Clocksquared, but in a tiny wristwatch package. This gives rise to a major challenge, as …

Animated Heart

“Just in time for Valentines day, a small gadget to be given to your sweetheart: a heart that loops through multiple animations. It nicely fits on a desk or table to have your loved one remember you! This animated heart …

Project  Charliewatch

Charliewatch

“”Analog” watch with 60+12 Charlieplexed LEDs. Based on Travis Goodspeed’s GoodWatch21 schematic, using the CC430F5137IRGZR CPU, which doesn’t have the LCD controller of the CC430F6xxx in the GoodWatch. There are also pads for a six pin EZfet …

Building a ‘papercraft’ LED marquee

“Long, dark winter nights demand some tinkering and crafts. Arduino LED projects are fun, but custom circuit boards might not always be in the budget. Thankfully, discrete LEDs can be found on Ebay for less than 1¢ apiece, and cardboard …

The Cheapest and Simplest Pulse Counter

“This counter is made only from an ATtiny13 and LED diodes. Did you ever need a cheap and simple (with one digit only) pulse counter? This is the maximum optimization and simplification. Thanks to Charlie Allen.”

LED multiplexing layouts for hand-crafting

“Have you ever wanted to build a LED matrix display using hand-crafting methods, such as sewing, weaving, or papercraft? Designing and fabricating complex LED projects by hand, while making use of limited input-output (i/o) pins on microcontrollers/Arduino, is …

Twelve PWM outputs from an ATtiny85

“This project describes how to get 12 analogue PWM outputs from an ATtiny85, so you can drive 12 LEDs with individual control over each LED’s brightness Each LED can be set to a brightness between 0 (off) and 63 …

ATtiny LED Matrix Display Badge

“An ATtiny85-based badge-size PCB that can display letters and numbers. Have you ever thought of making a badge-sized PCB that can display some letters, numbers, etc… or your name? In this project, I will be showing how I built a …