Lab 15: Scrolling text message on an LED dot-matrix display
In Lab 12, we learned about the basic structure of a monochrome (single color) LED dot matrix and its interface with a microcontroller to display static characters and symbols. Today’s lab is its continuation, and we will be discussing on displaying a scrolling text message on a 16×8 LED dot matrix. The microcontroller used is again the same PIC18F2550 from StartUSB for PIC board. The 16 columns of the LED matrix are driven individually by two shift registers (74HC595), whereas the eight combined rows are driven by the decoded outputs from a decade counter (CD4017). In Lab 12, columns were scanned, but here we will be scanning across the rows and feed the column lines with appropriate logic levels. An analog input from a potentiometer is read by the microcontroller to determine the speed of the scrolling message. The technique will be demonstrated for right to left scroll, but can be easily implemented for scrolling in other directions. The program for PIC18F2550 is developed with mikroC Pro for PIC compiler.
Scrolling message display on 16x8 LED dot matrix