Circuit Lake

The goal of the project is to build a self-reconfiguring LED Dot matrix display. It uses ATmega48 based modular LED matrix display unit, Kingbright TA20-11EWA LED matrix array, which can be chained together to form a self reconfiguring and arbitrary length LED matrix display. A head unit consisting of an ATmega168 is placed at the start of the chain to control the overall display.

Ee Chen, the project designer, said that both a low speed and a high speed version of the units exist. The low speed version utilises a half duplex serial communications protocol over one pin which only allows the LED dot matrix units to exchange data with their immediate neighbour. In contrast, the high speed version utilises a multi-drop half duplex synchronous serial protocol which allows the head unit to address any unit in the chain at the expense of extra connector pins. The low speed version is adequate for typical usage as a scrolling sign. The high speed version is capable of displaying real time animation or other applications that demand a high frame rate.

Hot plugging and automatic configuration is possible in the low speed version due to the point to point nature of the communications, assuming sufficient capacitance on the supply voltage rail.