The MAX7219 is a Integrated Circuit that can drive 64 individual LED's or up to 8 digits of 7-segment display's or a LED matrix of 8x8. The driver implements a SPI interface that can be controlled from a microcontroller using only three I/O pins.
Pulse Width Modulation allows microcontrollers to dim lights, control motor speeds, fan speeds and generate analog voltages. By changing the length of the pulse, the output can be controlled. In this project the brightness of a LED is controlled by PWM with the ATMega8 microcontroller.
This is a good project for beginners. It is easy to build.This running LED light uses seven bicolor led's red and yellow, they light up in a pattern that can be made within the program code.The program code is written in assembler. ATMELs AVR STUDIO is used to write the program.
An RGB LED is a LED which has three LED's integrated in one packaging. These LED's have the colors Red, Green, and Blue. The RGB LED used here is a hyperflux LED with common cathode, which can draw 20mA current. Such a LED costs about 2€. With these three colours you can mix to any colour.
This project is based on the timer/counter 0 example. It shows time, date and temparature on 7 segment displays. Instead of the LCD display the time is shown on a four digit 7 segment display with common cathode. The date and temparature is shown on a 7 segment LED display with comon anode.
In this project we make a pulsating LED by adjusting the brightness. The LED pulsates on and off. The brightness changes by PWM. The PWM is a made by the software instead of hardware. The circuit is simply a LED connected to pin0 of PORTB and ground via a current limiting resistor.