8x8 LED Matrix

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8x8 LED Matrix

Postby dushancc » Sun Mar 03, 2013 4:25 am

I bought 4  8x8 LED matrix modules from Lankatronics.
http://www.lankatronics.com/opto-electr ... thode.html

I also bought 4 max7219 driver chips for each matrix. As testing I hooked up one matrix to a 7219 chip. As there were no documentation related to the matrix, I wired it up according to the following tutorial.
http://www.gammon.com.au/forum/?id=11516

I did it twice but with no success I also tried arduino direct drive tutorial.

http://playground.arduino.cc/Main/DirectDriveLEDMatrix

Unfortunately  :cry:  :cry:  they both give me same exact output. The lights turn on the the rows begin to flicker. Just it. No letters or patterns. Can anyone give me a help to make this thing work  :)   ;)
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Re: 8x8 LED Matrix

Postby Neo » Mon Mar 04, 2013 1:43 am

Hello Dushan,

There could be many reasons.

1. Wiring issue
2. Timing (frequency) issue
etc...

First of all, can you use a 3V to power up the matrix to understand wiring diagram properly. Then integrate this to your Arduino board and enable each pin at a time. Later on you can use the Arduino direct drive example with proper frequency settings on the library to write to each row or column in about 30 or 60 frames per seconds. So the picture would become clear to the you.

Give us your feedback.
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Re: 8x8 LED Matrix

Postby SemiconductorCat » Wed Mar 06, 2013 1:47 pm

First recheck your wiring diagram.
Do you know how to recheck a wiring diagram with schematic in industry level? If no do a google research.
(Check every node , branch , make a list and tick it.)


Sounds familiar the situation.I think your MAX chip get reset every every cycle it feeds the row. This may happen
to transient current spikes taken by LED matrix. Try increasing the capacitors near MAX chip. if not working feedback.
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Re: 8x8 LED Matrix

Postby dushancc » Thu Mar 28, 2013 9:24 am

Thank you for your replies. I checked it again and I got to know that pin arrangement of cathodes and anodes differ from matrix from matrix. Finally I found the correct pin layout suitable for matrix I bought from lankatronics. It was a success  :clap: But now there is another problem  :? . When I upload the code in to the arduino it displays 2 characters "A" and "r". but then suddenly it vanishes off. I can again get the "A" character to be displayed by only pressing reset.

Please help me to get this thing work continuously.  8-)

Thank you
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Re: 8x8 LED Matrix

Postby Neo » Sun Apr 07, 2013 2:08 pm

Try to use . That seems robust.
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Re: 8x8 LED Matrix

Postby dushancc » Sun Apr 07, 2013 2:31 pm

Thank you very much. I got it to work. It was just a breadboard problem. I am currently doing well with LedControl library. I'll check your library too.

Thank you
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Re: 8x8 LED Matrix

Postby OtisMorales » Mon Sep 09, 2013 1:50 pm

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