After reading up on Project #21: "Creating an LED Matrix" from "The Arduino Workshop" I set out to find a 8x8 common cathode led matrix. I saw this MAX7219 8X8 Red Dot LED Matrix Kit on Amazon and even though I was looking to experiment with using two 74HC595's to control the rows and columns, this MAX7219 chip that did it all caught my curiosity. So I ordered the kit. Amazon Prime delivered quickly.
The kit was relatively easy to solder. Both the 8x8 display and the MAX7219 are socketed so you can easily remove them if you want to use in a different project. From the looks of it, the board can be easily cascaded with other devices to create larger displays. John Boxall does exactly that in his book "The Arduino Workshop" and posts a copy of the project online here.
One single MAX7219 can also control up to 8 7-segment displays. Unlike my prior example, where each 7 segment display is driven by an individual 74HC595, the MAX7219 multiplexes the 7 segment displays so that only one is on at a time. This cuts the current usage and because of the persistence of vision it appears that all 8 digits are on constantly.
The LedControl Arduino library has full support for the MAX7219 to control an 8x8 display. The library does all the shifting out and multiplexing of row and column LEDs. All you do is tell it the row and column of the LED you would like to turn on or off!
So here is a peek at my finished MAX7219 8X8 Red Dot LED Matrix Kit running the test program.