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LED Lighting Control using the MC9S08AW60, Rev. 1
Freescale Semiconductor 7
Chapter 1
Introduction
1.1 Introduction
This manual describes a reference design of a multi-color LED lighting control solution by using the
MC9S08AW60 Microcontroller.
Using a microcontroller (MCU) to control the red/green/blue (RGB) color LEDs increases system flexibility
and functionality for the next generation of lighting applications, architectural/entertainment lighting or
LCD backlighting, that require a smart and adaptive control methodology to ensure optimized color space
rendering for various display contents, excellent color contrast for realistic display scene and a consistent
color setting in manufacturing. In many cases, these new applications are controlled by a central control
unit that requires a connectivity interface that can be implemented at a low cost using MCU-based lighting
controller.
A compact light-box with more than a million display colors is implemented to demonstrate the
advantages of using MCU to control RGB color LEDs with different luminosity settings. The average
current through each color LED is controlled by an individual PWM signal generated from MCU and the
LED luminosity is almost in linear relationship with the pulse width of the driving PWM signal. The final
display color is determined on the mix of light emitted by RGB LEDs, so one of the simple methods to set
the light source in different color is changing the RGB PWM duty cycles equal to the corresponding mixing
ratio required for a particular color. In addition, a serial control protocol with user interface is also
developed as a communication link to control and monitor system parameters through a personal
computer.
All hardware schematic diagrams and firmware source codes are available as reference materials.
1.2 Features
• Apply for architectural/entertainment lighting or LCD backlighting applications
• Exceptional color mixing
• Pre-set or dynamic RGB colors
• High resolution on dimming control
• Automatic white balance tracking on dimming
• Flexible connectivity interface
• User friendly control menu