Adafruit: Bicolor LED Square Pixel Matrix

 Overview: 2 Wiring:  1 Code:    1, should have called ioctl directly git/Compiles with make: 2 Demo:    2 Total:   8-1(late) = 7 Comments: It works, but it isn't pretty.

Page by Alex Drane, Peter Ngo

Summary
This page details project work done while working on the 8x8 Bicolor LED Pixel Matrix from Adafruit found here: Store Link

This device responds to standard I2C write and Read commands on the 3rd I2C Device at 0x70 device address.

IMPORTANT!!! When soldering the led matrix to the controller make sure that it is placed correctly. If it is not, then the device will still communicate but the LED Matrix will not turn on.

Wiring Information
The device relies on the 5V source on the board and to insure functionality an I2C voltage level converter is used to boost the 3.3V I2C voltage to 5V. The voltage level converter is hooked up according to the photo. Starting from the top left of the device: SCL 5V, 5V Rail, Reset(Pulled up to 3.3V), SCL 3.3V In. Bottom Left: SDA 5V, Ground, 3.3V, SDA 3.3V.

The LED Matrix is wired from left to right: 5V, Ground, SDA, SCL.

The tenth pin from the Right on row 1 of the P9 IO Rail on the Beagle (Count from the 5V Line in) is the SCL pin and the pin on row 2 is the SDA pin. Starting from the right on P9 top row is: Ground, 3.3V, Skip, 5V.

The wiring instructions are hard to follow. Which header on the bone are you using? P9?



Code
The code is hosted on github here: 8x8 Led Grid Basic Code

You should have called iotcl directly rather than using i2cset

This is a very simple code implementation that is only to verify that the matrix works. For a further implementation of the 8x8 Matrix see the Mini Project 4 project here: Node.js Advanced Implementation