ATMega8 Based Brain Machine

The project is an improved version of a former brain machine where the improvements include selection between multiple stored frequencies, importing of gnaural schedule files, arbitrary frequencies, and sine-wave audio.

An ATMega8 is used as the basis of the hardware which uses only very few of the I/O ports including one for a pushbutton, two for LEDs, and two for audio. Another controller that has an 8-bit timer with two PWM channels can also use this microcontroller. A piece of prototyping PCB is also added which contains two AA cells, connectors for headphones & glasses, a switch, two resistors, and four capacitors.

The main code is used to set the DDS parameters accordingly, iterate thru the sequence of brainwaves to be played, and waits for some volatile variables to change. The controller is put into power down sleep mode if the sequence is done. The audio is pushed out by a PWM and considered as DDS-generated sine-waves. Although the PWM frequency shows when the inductance of the headphones comes into play, the resulting waveform is quite nice when viewed without headphones connected. The DDS tightly integrates LED blinking without timing loops.

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