Hello,
For starters, I'm a newbie so please excuse the fact that I'm not very knowledgeable.
I've been playing around with LED Matrix's and Max7219 chips as separate components. I got everything going without too much trouble. Then I saw these modules and thought it was a great way to daisy chain a number of these without having all of the wires connecting the LED Matrix to the Max 7219 chips.
So, I bought 5 of these modules on eBay. Yep. 5 of them.
What I noticed was that the first time I powered the arduino with these modules attached, even before I had a chance to upload the program, a number of LED's were lit in a pattern. I then uploaded the program and it had no effect.
I've attached a photo showing the LED pattern.
Now, I don't know whether this issue is the same as yours. However, I have a couple of common cathode LED Matrix's. So, in the hope that the issue I am having is the same as yours in which you describe the LED Matrix board being set up for common cathode but the LED Matrix on the board being common anode, I took the LED Matrix off the board and replaced it with what I know to be a common cathode LED Matrix. Unfortunately, that didn't fix the issue. Instead I had different LED lights being lit and not being able to change the LED's through the program.
So, I don't know if it is a common anode LED Matrix attached to a Common cathode board or vice versa or something else entirely.
All I know is that I just expected it to work.
I plugged the VCC on the board to 5V on the arduino.
I plugged the Gnd on the board to Gnd on the arduino.
I plugged the DIN to pin 2 on the Arduino
I plugged the Load/CS to pin 3 on the Arduino.
And I plugged the Clock to pin 4 on the Arduino.
It;s great that you got things working. However, for me it kind of defeats the purpose if I end up with
a whole bunch of wires connecting the board to the LED Matrix as the reason I got the module was because it represented a clean way for me to play around with a number of LED matrixes without the bother of having heaps of wires.
Is there another way I can get these modules to work?
Should they have worked when I took out the LED Matrix on the board and replaced it with a common cathode LED Matrix if the issue was the same as your issue?
I'm actually quite surprised that these items are sold without any quality control. It might be okay for a seasoned person who can work around the issue and find a solution. However, as a newbie, this pretty much leaves me lost at sea and with no other option but to just write the cost of these modules off as money down the drain.
I've attached two pics. One is me getting two of these LED Matrix's to work the old fashioned way with two Max7219 IC's and all the wires connecting them. The second pic is what is appearing on these LED Matrix Modules I bought. It's the same collection of LED's appearing in all five modules.
Cheers
Tony
LED matrix module. Chinese sellers do not see the difference between the common cathode (HL-M1388AR) LED matrix and common anode (HL-M1388BR) LED matrix. This PCB designed for common cathode LED matrix module. But the LED Matrix on it (HL-M1388BR) - is common anode LED matrix module. Do not worry, it can be fixed – just rewire it properly:
