Adafruit: Bicolor LED Square Pixel Matrix

Revision as of 02:47, 17 October 2012 by Draneaw (talk | contribs) (Means of Making "Something" Visible)
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Overview: 2
Wiring:   0
Code:     1
git/Compiles with make: 0
Demo:     0
Total:    3
Comments: I have a level converter you can try, or 
let's switch you to another device so you can have some success.  

What do you prefer?

thumb‎ Embedded Linux Class by Mark A. Yoder

Page by Alex Drane, Peter Ngo


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

Current Status

The current LED Matrix is fully functional except for a minor issue with alignment of the rows. It is shifted up by one LED and puts the top row at the bottom. The former issues encountered with the device was due to a miss-wiring of the matrix to the I2C Part.

Means of Making "Something" Visible (Outdated 10/16/2012)

The following section is out of date but illustrates the issue encountered when the LED Matrix was miss-attached but is a good record of those events. While we cannot currently turn on an individual pixel we were able to establish that the device was responding to I2C input. Directions:

i2cset -y 3 0x70 0x21
i2cset -y 3 0x70 0x81
i2cset -y 3 0x70 0xA1

The bottom row should be visible, barely. What you have done is turn on the devices oscillator, turn on the LED screen, and set it to INT active low control. No other combination currently makes the device do anything. Brightness control does not effect the row. We did show that we were turning the oscillator on and off by using:

i2cset 3 0x70 0x20

To turn off the row. Currently I have no explanation for why it does not work.

I am able to program the 0x00-0x0f memory address range with values that I can read back and that should control the LED matrix when the

i2cset -y 3 0x70 0xA0

Command is used. This does nothing. Brightness was checked at 0xEF and 0xE0 to make sure that brightness was not being misunderstood. This has no effect.

Setting the display to blinking (0x83, 0x85) also did nothing.

Code provided by Adafruit was for the Adrino board and using it as a guide I established that it should be possible to control the screen manually. I acquired the data sheet for the HT16k33 and that was how I was able to experiment as I did above.

thumb‎ Embedded Linux Class by Mark A. Yoder