ATtiny13 controlled LED Christmas lights

Posted on Monday, December 19th, 2011 in AVR, Holiday by the machinegeek

A simple example of a Christmas light project using store bought LED lights and components you probably have lying around the shop. Mark VandeWettering found a set of battery powered LED Christmas lights and decided to combine this this an ATtiny13 to make an MCU controlled lighting display. He explains:

I found a set of battery powered LED Christmas lights at CVS on sale for $.99 each. I took the lights out, and found that they consisted of two strands: one of 4 red and 4 yellow LEDs, and the other of 4 blue and 3 green LEDS. Each strand is wired in parallel and draws about 20ma at 3 volts. I have a few ATtiny13’s lying around, which can use between 2.7 and 5.5 volts supply. I think for this test, I’ll wire up a little 7805 regulator to provide 5V, and then control each strand with one of the two PWM outputs. If I want to drive the strings directly from the microcontroller, I’ll have to insert another 50 ohms of resistance to limit the current to around 20ma per pin. I could also add a 1K resistor and a small NPN transistor to drive each pin at the higher voltage. At 5V, the strand will draw about 120ma.

You can find the source code on Mark’s brainwagon webpage.

This entry was posted on Monday, December 19th, 2011 at 5:00 pm and is filed under AVR, Holiday. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.

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