(last updated: 2006/11/21)
Purpose: Create a visual display which turns on/off LEDs in attention-getting patterns.
Overview
LEDStripe has three main components, 16 bright LEDs, serial-to-parallel shift registers, and a microcontroller. The microcontroller, Motorola HC908QY4, includes programming to perform 11 blink patterns. The blink pattern is selected by adjusting a potentiometer. The selected blink pattern determines a bit pattern which is then shifted serially to the serial-to-parallel shift registers. A low state on the output of a shift register causes the connected LED to be on; otherwise, it is off.
The design is presented in the following diagram:
To work out the blink patterns sequencing before implementation into the HC908QY4 code, a Java applet called “jLEDStripe” was created. This applet shows 16 round icons which represent the 16 LEDs. A GUI button changes the blink pattern. The program runs the selected blink pattern, changing the icons to either solid red (on) or white (off).
Photograph of prototype:
On the left is the M68DEMOQT4 demonstration board from Motorola. The shift registers and LEDs are mounted on the solderless breadboard.
LEDStripe was originally designed to be a hazard warning signal which would be placed near a disabled car. It could also be used at a construction site for hazard warning, or in a department store display to set off a product.
Specification
Download
LED_Stripe_Design_Spec.doc - Design Specification (includes schematic and software flowchart)
led_stripe - project files for the Motorola HC908QY4 (assembly, PE Micros WinIDE project)
led_stripe.S19 - executable
jled_stripe - project files for jLEDStripe (applet, JBuilder6 project)
Copyright Steven R. Nickels, 2008. All rights reserved.