Electronic Odyssey – pt.1.5 – First steps, and some info on driving 8×8 rgb matrixes

So after receiving my arduino last week from Seeed studio, I have been itching to give it a roll.  Unfortunately, as I mentioned before, I stupidly forgot to pick up a breadboard so I have been pretty limited to what I can do.  That has not stopped me from hooking up a single LED and my giant mushroom button!  That is the standard 2nd or 3rd development tutorial step.

I then set to work creating a toggle’d light switch with the button.  One press turns it on, next press turns it off kind of thing.  The problem is that you experience a phenomena called bouncing where the light may not do exactly what you want it to do when you activate the switch.  I thought I could figure out how to de-bounce the input from the switch myself, however it was a bit more of a pain that I thought it might be.

I think my next step will be to get a serial com app working to do communication from the computer to the arduino – probably just turning the led on and off with a mouse click.  I am pretty limited with my hardware selection right now, so I may as well move forward with the software.

Anyhow, on another note I bought a bunch more stuff to play with from DigiKey, including the breadboard I am in need of currently and some other surprises.  I will post on that later after the shipment arrives.  What I did get allready, however, was my 8×8 RGB LED matrix from Seeed Studio, via ebay.

When I saw the matrix on ebay, for $22 no less, I had to have it.  There is so much potential for what I can do with it, so I jumped on the deal.  Unfortunately there is no real ‘out of the box’ solution to hook the matrix up to ANYTHING right now.  From what I understand, it is not a very difficult thing to control with a microcontroller, however it does take some specialized components because the matrix itself consists of 192 individual LEDs, and you must control them using only 32 pins on the matrix, and even fewer pins on the arduino itself.

I have been looking into options for controlling this thing now and have found a few answers, but nothing definitive yet:

  1. Nick can help me build a controller from scratch – it is certainly within his capability, however I don’t want to pester him and assembly would be a bit ragged
  2. I found this unit at SparkFun which looks pretty darn nice, however there is one problem – they will not sell the controller without the matrix, even though they sell the matrix without the controller.  Also, the price is a bit harsh.  Ultimately I may end up going with one of these units, as it looks quality + they have some decent example code and some kind of API for working with it.  Now I just wish I could get the controller!  I wonder if I could copy their design, use their firmware, and get it done cheaper?
  3. Seeed Studio appears to be developing some kind of matrix controller, called the Rainbowduino.  I am looking forward to its release, however it has been delayed significantly – it was supposed to be released in February.  Also, the specs are getting a bit more scary than I am currently prepared to deal with – no USB, pick your own micro to use is a bit beyond my level at the moment.  That said, the specs are not out yet so I will wait and see.
  4. While trolling over on the Seeed studio blog and Forum, I came across Robert who is working on creating a matrix controller.  He has a blog over at My2µF He seems to know what he is doing, he got the matrix and PCB’s fabbed by seeed, and is currently working on connecting the matrix controllers together over the i2c interface.  It looked like he had some extra PCB’s, so I asked him if he would sell me a complete unit – he agreed, but cautioned me that it may not be the most user friendly device.

So for now I have not made a decision on how to drive my matrix.  I think I am going to wait and see what Seeed has to offer in the rainbowduino, they said it will probably hit the market in the next 2-3 weeks.  I have plenty of learning to do before I am ready for the matrix anyhow.  After that I think Robert will be my 2nd choice.

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2 Responses to “Electronic Odyssey – pt.1.5 – First steps, and some info on driving 8×8 rgb matrixes”

  1. stonechild April 9, 2009 at 1:01 pm #

    Funny. I got my 8×8 Matrix from Seeed Studio on eBay too. I’ve spent some more time looking at the schematic that I found at the the sparkfun site:

    http://www.sparkfun.com/datasheets/Components/matrix_backpack.pdf

    Controlling the matrix is not as complicated as it seems. It’s still complicated, though, and also from the software side. The controller is just a simple Atmega, three 8 bit Shift Register DIP-16s (74LSC595), and the matrix. I just received 10 of the 74HC595s from an eBay seller figuring they would be useful, since I come across lots of references to them when dealing with multiple LEDS. Now I have to find out if the HC – LS in the part name makes a difference. I would guess not.

    Stopped to look it up. The 74LS595 and the 74HC595 are functionally equivalent.

    I thought the Maker people had a video on Youtube that demonstrated the shift registers, but I can’t find it now. It’s basically the same as the the tutorial here:

    http://www.arduino.cc/en/Tutorial/ShiftOut

    I don’t have any breadboards yet. A soon as I get them, I’m going to try this out.

    • jafoca April 9, 2009 at 2:16 pm #

      Stone,

      It is good to see that you are making progress (conceptually at least!) – keep me updated on how it works once you get your breadboard in.

      Since I got a bunch of stuff from DigiKey, I have been pretty afraid of plugging anything in for fear of ruining it! I have been reading the book I mentioned so that I know better what I am getting myself into…

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