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Topic: MAXX 7219 powering 5mm LEDs matrix (Read 71 times) previous topic - next topic

panaroni

I am developing a box that counts up when you press the button.. Kinda like a score keeper.. see pics..

there are 2 32mmx32mm 8x8 LED matrix for the score of each player with 2 players maximum. current module here: https://www.aliexpress.com/item/32909248031.html

because the game/score is being shown on Facebook live, it turns out these 32mmx32mm led modules are too small. I need to make the numbers bigger.

I found these larger 60.2mm X 60.2mm red, common cathode, 8x8 LED matrix on ebay..
https://www.ebay.com/itm/10-LED-Dot-Matrix-Display-8x8-5mm-Red-Common-Anode-16-P/372343820877

they are both common cathode 16p modules.  I soldered 16 wires from the back of the original module and used DuPont wires to plug into the 16 pins on the larger display.

I'm basically thinking they two displays are the same and hoping the Maxx7219 can run the new larger displays.

I get FULL RED on the new large display when hooking it up that way.

I soldered the wires to the back of the module so could also plug original module in at the same time..

the original module works fine.. even while the bigger module soldered to the back stays full red.

attached is also the schematic of the new larger modules..

because I can move wires around I'm thinking this COULD still work if I hook them up the right way..

currently I have pin 1 to 1 and 16 to 16 and everything matches in between. 

guessing the wires are crossed..

any help would be appreciated!!

I wonder if I should try connecting it 8 different ways with the 8p rows stay together just change location and orientation of the 2 - 8p rows..

thanks soo much.
Pete





Riva

Not all 8x8 LED matrix displays have the same pinout on the back so connecting the different displays using the same wiring may not work. You need to find the pinout wiring for both displays and then wire the bigger one using the same row/column sequence as the small display.
Don't PM me for help as I will ignore it.

Paul__B

#2
May 24, 2020, 08:58 am Last Edit: May 24, 2020, 09:00 am by Paul__B







Not all 8x8 LED matrix displays have the same pinout on the back
That's not quite the case here.  It does have the same pinout - sort of - but ... the clue is here:

I get FULL RED on the new large display when hooking it up that way.
Aha!  That is the clue - or one clue at least.  All are red.  :smiley-eek:

I found these larger 60.2mm X 60.2mm red, common cathode, 8x8 LED matrix on ebay..
https://www.ebay.com/itm/10-LED-Dot-Matrix-Display-8x8-5mm-Red-Common-Anode-16-P/372343820877
No, you didn't!  Take a look at the URL itself and the description on that page.  What does it say?

There are two versions of each of these displays.  The terms "common cathode" and "common anode" are commonly used but are nonsensical for arrays.  It would be more correct to call them "row cathode" and "row anode", all the LEDs are reversed between the two versions.

You will have to take the pin diagram

and wire it to exchange the pin numbers for each row with the corresponding column - 13 with 9, 14 with 3 and so on.


panaroni

Thank you for helping with my project and correcting that I ordered common anode replacements when I should have bought common cathode.   it should still work, right? so, I have basically swapped pin 1-8 in order with pins 9-16 in order on the LED Matrix.  it shows scrolling text so thats promising but I have those 4 bright red's and the rest seem real dim.  I have both displays connected so you can see what it should look like..  its just a sample code. 

did I hook it up as you said?  I'm not sure..

here's the link to the video of what its doing now.
https://youtu.be/9etZU2nVwk0

thank you for helping!!

Pete

Paul__B

#4
May 25, 2020, 01:44 pm Last Edit: May 25, 2020, 01:45 pm by Paul__B



Not sure what is going on with the four "stuck" LEDs!

It probably will be a bit dim if you have paralleled both the old and new displays.

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