Ethernet Interface for LED Matrix Display

LEDMATRIX are 16x16 LED matrix units with a green and a red LED per pixel allowing each pixel to be switched to either green, red, amber or off. The goal of this LEDMATRIX project was to build a 80x32 pixel display by arranging the displays in two rows with 5 displays each giving a total of 16*16*2*2*5 = 5120 LEDs to be controlled individually.

LED Matrix Display

This displays come with interated controllers and the data can be shifted into a single display using as few as 6 digital signals. By multiplexing some of the select signals all 10 displays can be controlled with a total of ten wires. Using a cheap ATmega32 microcontroller all ten displays can easily be controlled and updated in real time.

This kind of display is usually controlled via RS232. This has the disadvantage of being very slow and the display data is limited to simple text messages only with the microcontroller of the display doing the actual text drawing. Instead of doing it the same way i decided to use an ethernet interface for the LEDMATRIX display. Even the most simple ethernet interface i am using is fast enough to transfer graphics data in realtime from a PC to the display allowing to update the entire screen 50 times a second. The ethernet support of LEDMATRIX is based on the cirrus logic cs8900 chip which is e.g. supported by the free Procyon AVRlib which has been used for this project.

Download : Schematic, Source Code

Tag : LED Matrix Display, Ethernet Interface, AVR Project (src)

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