Building the LED Fader 2 Device

Figure 1 

The LED Fader 2 project was designed for driving LEDs wherein up to 16 outputs can be controlled.

In this design, there are 256 levels of brightness at a refresh rate of 100 Hz being provided since all 16 outputs are pulse width modulated. The outputs are controlled by designing a script language in which the AVR assembler for the ATmega8 and ATmega16 microcontrollers from Atmel is used to write the program. To control the PWM outputs and manipulating script execution, a number of commands are available on the scripts. Some special techniques are used for the LED Fader 2 since it is specifically made for dimming LEDs.

The main LED controlling command is used to control all fading on the PWM channels. The script will just start the fading and then immediately moves on the next command in the script since it will not wait for the fading to come to an end. The Timer1 interrupt is the heart of the PWM generation where it was called somewhere between 400 and 1600 times per second. According to the desired brightness of the LEDs, the timeslots for the interrupts are changed dynamically.

Rest of the project