L'Antre du Tryphon

The MAX7219 chip does a wonderful job when its time to drive either a 64 led matrix or an eight digit (seven segments) display. Only three wires are required: a chip select (CS), a data in (DIN) and a clock (CLK). The protocol is simple. I’ve written an Arduino library that implements this protocol. Specifications can be found at MAX7219.

The library comes with some code examples. Look in the File >> Examples >> CTTMAX7219 sub-menu in the Arduino IDE. Refer to the display and chip manufacturers to hook the display to the MAX7219 chip. This is straight forward. The display will likely need an external supply. If so, make sure that the Arduino board and the chip have a shared ground. You will need to modify the example code to specify the pins used to connect the DIN, CS and CLK pins of the chip to the Arduino. By default, these are:

/** Clock pin on the arduino. */
int pinCLK = 10;
/** Chip select pin on the arduino. */
int pinCS = 9;
/** Data IN on the arduino. */
int pinDIN = 8;

The download link of the library is CTTMAX7219_v1.0. You can install it through the Arduino IDE using the usual methods. Detailed information can be found at Installing Additional Arduino Libraries.