AtMega board and simple DSP tasks??

Using Arduino Audio
3

Also please don't use analogRead() if you care about performance.
Here is a simple example to read the A0 and output it using PWM on pin 3.

#include <stdint.h>
int speakerPin = 3; // Can be either 3 or 11, two PWM outputs connected to Timer 2
void startPlayback()
{
    pinMode(speakerPin, OUTPUT);

    // Set up Timer 2 to do pulse width modulation on the speaker
    // pin.

    // Use internal clock (datasheet p.160)
    ASSR &= ~(_BV(EXCLK) | _BV(AS2));

    // Set fast PWM mode  (p.157)
    TCCR2A |= _BV(WGM21) | _BV(WGM20);
    TCCR2B &= ~_BV(WGM22);

        // Do non-inverting PWM on pin OC2B (p.155)
        // On the Arduino this is pin 3.
        TCCR2A = (TCCR2A | _BV(COM2B1)) & ~_BV(COM2B0);
        TCCR2A &= ~(_BV(COM2A1) | _BV(COM2A0));
        // No prescaler (p.158)
        TCCR2B = (TCCR2B & ~(_BV(CS12) | _BV(CS11))) | _BV(CS10);
}


void setup()
{
       pinMode(ledPin, OUTPUT);
   OCR2B=0;
        startPlayback();
    ADMUX = (1<<REFS0)|(1<<ADLAR);
    ADCSRA = (1<<ADEN)|(1<<ADPS2);
}

void loop()
{
  // start single convertion
  // write ’1? to ADSC
  ADCSRA |= (1<<ADSC);
 
  // wait for conversion to complete
  // ADSC becomes ’0? again
  // till then, run loop continuously
  while(ADCSRA & (1<<ADSC));
  OCR2B=ADCH;

}

A tip to speed up DSP processing is process the previous byte while waiting for the next one.
Also note that this example ignores the lower 2 bits if you want the lower 2bits to get a total of 10 bits you will need to need to remove |(1<<ADLAR) then read ADCL first do something like this

	uint8_t temp=ADCL;
	uint16_t output=temp|(ADCH<<8);

Notices how I did not just do

ADCL|(ADCH<<8)

This is because ADCL must be read first.