Implementation of a Colorful RGB-LED Light Source with an 8-bit Microcontroller

This paper depicts the implementation of a colorful RGB-LED light source with an 8-bit microcontroller. The microcontroller regulates LED light output with pulse-width modulation current and changes the light color with the current ratios of red, green and blue LEDs. While the LED light output varies with temperature, the microcontroller stabilizes the light output of LED with feed-forward compensation and reduces the color deviation in chromaticity diagram. The color deviation is measured with a miniature spectrometer and the calibration of white balance is executed based on the chromaticity coordinates of the used red, green and blue LEDs. Some color points inside the chromaticity diagram and along the blackbody locus are tested to verify the performance of the RGB LED light source. Test results show that an 8-bit microcontroller may effectively regulate the light colors and brightness of a RGB combinational light source. The implemented RGB LED light source can be a good light fixture for mood lighting in somewhere, such as, hotels, restaurants, hospitals, advertisement walls and others.