Web Interface Controlled Ambient Light Bulb

The project illustrates the use of AVR web server devices in order to control a LED lamp and Ethernet for connectivity.

A pair of tri-color LEDs was driven by a small circuit along with a basic Tuxgraphics Ethernet board. The ANSI C99 is used to write the software which is supported by AVR libc. Each output channel of the LED lamp is driven using 8-bit timers so that the red, green, and blue will be given independent control. The timers are configured in fast PWM mode, repeatedly counting from 0 to 255 at a rate of one step every 8MHz tick. To range from fully OFF to full intensity output, the comparator register for each timer is set to a value between 0 and 255. To save power when all outputs are 0, extra code manages enabling and disabling the timer hardware blocks via the Power reduction Register.

A different timer is configured to generate an interrupt once every 4 milliseconds which enable changes in the light output to be sequenced. This drives the light sequencer which interprets a stream of control bytes to determine the PWM output settings in light driver.

Rest of the project