Nice tutorial from brandonhawkes on Instructables.

What are we making?

We are going to create a controllable 6×7 LED grid with minimal components.

Charlieplexing

Charlieplexing is a method to individually control more LEDs than pins used. This method is popular since it doesn’t require any additional components like shift registers.

It mostly works by changing the mode of two pins to an input and an output to light a specific LED. By cycling through and lighting up each LED at a time quick enough it gives the illusion of multiple LEDs being lit at once.

The formula for working out the amount of LEDs you can control from the amount of pins (N) you want to use is:

N*(N-1)

So 3 pins = 6 LEDs, 4 = 12, 5 = 20, 6 = 30, 7 = 42, 8 = 56, 9 = 72 and so on.

For this tutorial we are going to use 7 pins, so that means we have 42 LEDs that we can control.

Adafruit Huzzah

The Adafruit Huzzah is an ESP8266 breakout board – I used it for this project its easier to program and power compared to a bare ESP8266, but still is still super cheap. This board is great because it has built in WiFi, so we can add the ability to change the grid over the Internet.

Read more.

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