PWM controlled (pulsed) LED with an AVR ATmega microcontroller.

Based as an experiment with my AVR development board, showing you some use of a pulse width controlled rectangular signal. It's the proper way of controlling the brightness of an LED. Using three channels with a combined red, green, blue LED makes it possible to compose almost every color within the spectrum (not on the vid, though ;)

Notice: The human eye needs a non-linear (exponential) curve to recognize light level changes linearly, this is why in this video the LED seems to jump from low to high very fast and then just stay high for a long time, although it is perfectly linear. More sophisticated fading mechanisms respect that.

Category:

Science & Technology

Tags:

• AVR
• PWM
• pulse
• width
• modulation
• LED
• dimm
• brightness

[punisher129]

What is the usb connector for? Are you using it for programming the chip? Maybe with the aid of USBasp with AVRDUDE?

[linuxgeek81]

No, that would not require a USB port within the target application.

[linuxgeek81]

In the meantime I also use that port for programming the AVR...

[roomtek]

nice man.

[linuxgeek81]

where? oO

[chivukulark]

Hey Hi! its a nice demonstration. Presently I am working on the same kind of thing with AVRxmega128a and AVR dragon as debugger. Can you pls send me ur sample code, so that I can rectify my mistakes. This would help me a lot. Thank you. my email id is gachibowli.diwakar@aol.com

[RadiacaoDeFundo]

actually, the non linear response of the light is a property of the LEDs, not of the human eye, thats why it brightens all up at once. to make it linear, you should compensate by using a log-varying duty cycle =]