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Author Topic: Just wanted to share my 32 x 8 LED Matrix  (Read 2097 times)
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Raleigh, NC.
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so...4 max7219's,  4    8x8 martrices,   4    100 uF caps,  4      0.1 uF caps and 4    27 K ohm resistors later...



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Raleigh, NC.
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Oh yes and my arduino Nano.....

code is attached too...

find the max7219 playground schematic and have a good pinout for the matrix before you start connecting them...know the rows and columns...

* THE_BEST_SCROLL_32x8.ino (9.8 KB - downloaded 44 times.)
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Norfolk UK
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Is it meant to have that pixel column effect on each 8x8 matrix as it scrolls?
Other than that it looks good.
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Valencia, Spain
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Is it meant to have that pixel column effect on each 8x8 matrix as it scrolls?

It looks like the columns are off by one. A little software tweak should fix that, no problem...

Other than that it looks good.

Yep. Nicely laid out and plenty of capacitors!

PS: You could maybe put the resistors all facing the same way though... smiley
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Raleigh, NC.
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Ya I noticed the column effect....to me, its good to go..i have worked on this thing forever....One of these days, I want to make the 64 x 8 matrix...easy enough..just cascade more max7219s....just gotta get a large enough PCB
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Raleigh, NC.
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Hey Fungus,

You mention a little software tweak can fix the effect......can you check out my code in a thread above and show me maybe where it can fix it please?
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Norfolk UK
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I have altered a version of a scroll program you did try that was hard coded for just 2x matrix displays so it will scroll on 4 displays but don't have hardware to test it on. Fancy giving it a try and letting me know if it works? I have attached it in case you do.

* ScrollTest4MAX2.ino (15.11 KB - downloaded 28 times.)
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Raleigh, NC.
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Just uploaded it.....no difference in this compared to the video I posted....
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Norfolk UK
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Just uploaded it.....no difference in this compared to the video I posted....
Hmm, if it's scrolling across all 4 matrix displays now instead of just the two it did before and it still looks the same as the version in your video then maybe the matrix is not wired quite right. Can you slow down the scroll speed using either sketch (mine you increase 'const long scrollDelay = 70;') and video it again.
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Raleigh, NC.
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Yes, the delay lets it slow down......and I'm beginning to think you're right about the matrices not being wired quite right....I bought them on ebay...they have   XH-1088BRW   on the side of them....

This is what I have for reference but I'll look better for a good datasheet..

The picture is attached....


* IMG_4062[1].JPG (838.71 KB, 3264x2448 - viewed 33 times.)
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Norfolk UK
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I cannot find a datasheet for the matrix, maybe going back to the ebay seller and see if they have a picture on the website.

EDIT:
I have found a picture here http://www.ebay.co.uk/itm/16-LED-Dot-Matrix-Display-3mm-8x8-Red-Common-Anode-16pin-64-LED-Displays-module-/150963896624?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item2326264130
« Last Edit: December 12, 2012, 01:21:27 pm by Riva » Logged

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Raleigh, NC.
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I am making a new layout by manually checking the rows and columns using a power suply to see them illuminate.....

I'l update you soon..I already found  R6 / C6 and  R2 / C2 to be swapped.....
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Norfolk UK
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Comparing your picture to the ebay drawing your rows look fine but columns are a bit mixed. I have put your pinout in last column. Best bet is to buzz the matrix out as your doing to be sure.
Code:
PIN  R/C  Your Picture
01 = R5    r5
02 = R7    r7
03 = C2    c7
04 = C3    c6
05 = R8    r8
06 = C5    c4
07 = R6    r6
08 = R3    r3
09 = R1    r1
10 = C4    c5
11 = C6    c3
12 = R4    r4
13 = C1    c8
14 = R2    r2
15 = C7    c2
16 = C8    c1
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Raleigh, NC.
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Thanks for that....Nice find...I'll do some switching around soonish and update the forum...
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Raleigh, NC.
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Riva,

so I built just a small quick 8 x 8 with a max7219 using my Uno using the pinout you found....

didn't go so well.....the letters scrolled but were upside down and backwards.....

thats what I hate about these matrices ..they can go in anyway and especially with how the code is written can make them flip all over the place.....Oh well it works good enough for me
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