Open Source Dot Matrix Clock

Overview

The project intends to create an open source portion on a dot matrix clock software.

Explanation

The device provides a total of 1280 LEDs from a 40x16 display with 2 LEDs per pixel. The brightness problems with the display is prevented by the constant current LED sink chips. A 12 MIPS throughput is given by the PIC18F4550 microcontroller that runs off the PLL on a 16MHz oscillator. The development would be nearly impossible without using a breakout board while the board connector utilizes 41-pin high density board. the 4 buttons can be read through the board to board connector although they are no connected to the display microcontroller. For fast communication with the microcontroller, an 8-bit parallel bus with CS, R/W, and CLK pins is used.

By specifying start coordinates, the built-in fonts would not be restricted by rows or columns. Each dot has 16 possible colors from pixel-by-pixel control of graphics which allows direct memory dumps into the display for the possibility of animated things. This requires having a powerful enough processor on the master side of the bus. To prevent overwriting the buffer currently being displayed, triple buffering is employed by extension.