MD_MAXPanel LED Matrix Panel Arduino Library  1.2
Library to control a panel of connected MAX72XX devices
Arduino LED Matrix Panel Library

The MD_MAXPanel Library

This library implements functions that allows cascaded MAX72xx LED modules (64 individual LEDs)to be used for LED matrix panels, allowing the programmer to use the LED matrix as an pixel addressable display device, as shown in the photo below.

MAXPanel_Display.jpg
MD_MAXPanel Display Panel

The MAX7219/MAX7221 are compact, serial input/output display drivers that interface microprocessors to 7-segment numeric LED displays of up to 8 digits, bar-graph displays, or 64 individual LEDs.

A 4-wire serial interface (SPI) allows the devices to be cascaded, with communications passed through the first device in the chain to all others. Individual elements may be addressed and updated without rewriting the entire display.

In order for this library to work, the MD_MAX72xx library must be installed and the correct LED module type selected. The individual LED modules must also be arranged in a zig-zag fashion, as shown in the figure below. The number of modules per row and the number of rows may vary, but the arrangement of the modules must follow the example.

MAXPanel_Diagram.jpg
MD_MAXPanel Module Arrangement

The wiring for the modules can be simplified as the only signal that needs to be truly cascaded is the MD_MAX72xx IC Data Out to the next IC Data In. The rest can be wired in parallel, as shown in the photo.

MAXPanel_Wiring.jpg
MD_MAXPanel Module Wiring

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