[SOLVED] help with 8x8 LED matrix DIY kit pcb connection

Other Hardware LEDs and Multiplexing
1

I bought 10 of the 8x8 LED matrix DIY kit which consists of 8x8 LED matrix and a PCB with MAX7219 already soldered on and with connections to the 16 LED pins.

The MAX7219 to LED pin connections are as follows:

       MAX7219     8x8 maxtrix
       =======     =======
SegD   23          14
SegDP  22           5
SegE   21           3
SegC   20           2
SegG   17           8
SegB   16          12
SegF   15           7
SegA   14          11
Dig1   11           6
Dig6   10          15 
Dig7   8           13
Dig3   7            4
Dig2   6           16
Dig6   5           10
Dig4   3            9
Dig0   2            1

Those connections are completely differently from the connections I have been using at Arduino Playground - MAX72XXHardware

MAX7219     8x8 matrix
=======     =======
23           6
22          13
21          11
20          10
17          16
16           4
15          15
14           3
11          14
10           7 
8            5
7           12
6            8
5            2
3            1
2            9

I am using the LedControl library.

Now, I am confused with how to make these parts work.

Do I have to re-wire?

SOLUTION:

My PCB has the lettering FC-16 DISY1.

Using Google, I found a Japanese blog written by a person who also bought the same eBay item as I did. The blog is at http://www.beax.net/diary/?date=20150114

It is in entiredly in Japanese, but using Google translation and taking a close look at his photographs it appears that the 8x8 LED matrix needs to be inserted upside down. Usually the part number is on the "bottom" edge, but he was able to get the maxtrix to work by rotating the matrix so that the part number is on the "top".

Note that if you have the Arduino ---> 8x8 matrix connection, then row 1, column 1 is at the lower right not the upper left.

2

Haven't looked into all the details, but they are of course, the proper "stackable" displays as distinct from the really crude ones with the DIP chip.

On mine, the lettering on the side of the display (which also corresponds to a little "pip" in the middle - the only actual way of identifying one side or the other) is on the side opposite the "IN - OUT" description on the PCB.

Note that these displays do not have the 10 µF capacitor (but since they directly connect in a chain, it is not quite as critical) - you should probably add a 22 or 47 µF capacitor, repeated every three units or so when you chain them.

3

The PCBs that I bought have FC-16 DISY1 near one set of LED pins and IN and OUT near the other set of LED pins.

I was expecting that pin 1 of the LED matrix would at the top left corner, but the PCB designer had other ideas so pin 1 is down at the bottom right corner near the OUT.

I will be adding filter capacitors for sure.