Just wanted to share my 32 x 8 LED Matrix

so...4 max7219's, 4 8x8 martrices, 4 100 uF caps, 4 0.1 uF caps and 4 27 K ohm resistors later...

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)

Is it meant to have that pixel column effect on each 8x8 matrix as it scrolls?
Other than that it looks good.

Riva:
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...

Riva:
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... :slight_smile:

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

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?

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 (15.1 KB)

Just uploaded it.....no difference in this compared to the video I posted....

Aaron_dyer:
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.

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

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

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.....

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.

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

Thanks for that....Nice find...I'll do some switching around soonish and update the forum...

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

Upside down and backwards is just the row/column order reversed. The definitive answer is to buzz the rows and columns out using a battery and resistor and then wire to suit. The video you originally posted was very close to perfect. The rows appeared to be fine and only a couple of columns were out. Try doing a sequence of setLed going from column 0 to column 7 and compare to what column lights up you will then find the problem.

Aaron_dyer:
You mention a little software tweak can fix the effect......

Definitely.

Aaron_dyer:
can you check out my code in a thread above and show me maybe where it can fix it please?

What would you learn if I do it?

You need to learn to debug things. Start by writing a program to light up individual LEDs all across the array and see if you get what you expect.