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PWM LED Driver on Quadcopter - Summary

posted Mar 9, 2015, 11:44 PM by Neil Caulfield   [ updated Mar 10, 2015, 12:18 AM ]
Project Date: July 2014
Total Time: approx. 30 hours
Requirements: Arduino programming language, soldering, understanding of analog circuitry

This project involves implementing some generic 12 volt LED strips onto the arms of a quadcopter frame. This can be done with any RGB LED, but these high intensity strips are ideal for their wide viewing angle and their ease of application. The demonstration below uses simple on-off code, generating 8 colors (red, green, blue, yellow, magenta, cyan, white) by switching on the 3 colors to make different combinations. PWM based control can easily replace this to generate 6 million colors and fade patterns. PWM (pulse width modulation) is a type of waveform that can be used to carry (usually analog) information. The LED's brightness is determined by the duty cycle of the pulse while active. 

A duty cycle of 100% will power the LED at full brightness, 50% will make it half the brightness. This concept combined with the red, green, and blue LEDs allows for a virtually infinite number of colors to be generated. 

The code was set up so the pattern could be selected with a PWM input from an RC radio normally used to drive servos or speed controllers. In the cases below, the AUX channel on my Spektrum radios. 

It can be seen in flight with other modifications here:

A Tutorial for a PWM light controller will be coming soon.