Review on 🎄 Onyehn 2pcs/Lots MAX7219 Dot Matrix Module (Red Light) 4 in 1 Display: Christmas Decoration DIY Letters Electronic Display for Arduino Microcontroller with 5Pin Line by Jermaine Krishnamoorthy

Each of these devices is 5" long, 1.25" tall and 0.5" thick. I used the code described by the devil man and modified the hardware description as he described. I made another change. This is the #define MAX_DEVICES 11 statement. By maximum devices, the code means each individual module in the module. Each module has 4 units. So MAX_DEVICES should be a multiple of 4. Since I used 4 modules I changed MAX_DEVICES to 16. Then I found that I get inconsistent results with modules connected by wires. I added a couple of connectors on the output end of each module so I could plug one into the other and it all worked great with the Arduino code. I wanted to have a Merry Christmas 2019 sign in my window by next Christmas. They are too small for this use. I plan to use them in my HO train layout to make traffic signs. I ordered another larger unit to fit my Christmas plans.