AVR PCM audio: Playing 8 bit PCM using any AVR microcontroller--The simplest way

Monday, November 8, 2010

Playing 8 bit PCM using any AVR microcontroller--The simplest way

This is a simple procedure to play PCM audio on any AVR microcontroller. AVR's high speed PWM is used to play the audio. It almost sound fine and can be used for simple projects that require sound effects. The code is compiled in winavr GCC compiler. The microcontroller used is ATmega32, though any AVR processor can be used for the purpose. The header file included in this project contains a converted wav file which plays "its working".

The circuit:

Step 1:
Create a wav file (if you don't have any). The following link convert text to speech. Save it as .wav file.

here http://www2.research.att.com/~ttsweb/tts/demo.php

Step 2:
Convert the created wav file into 8 bit unsigned 8000 samples per second wav file using the software switch from NCH.

http://www.nch.com.au/switch/index.html

Step3:
Convert the 8 bit wav file to a sample c file using the software below.

http://darkfader.net/ngpc/files/wav2c.zip

Step4:
Copy the created samples onto the header file pcm_sample and save it.

Step5:
Compile using win GCC. The source code is provided below.

The main program:

/*
ATmega32 @ 8MHz
Plays an 8bit/8000 sample PCM audio on OC1A output
*/

#include <stdint.h>
#include <avr/io.h>
#include <avr/pgmspace.h>
#include "pcm_sample.h"
#include <avr/interrupt.h>
#define SAMPLE_RATE 8000;

volatile uint16_t sample;
int sample_count;

/* initialise the PWM */
void pwm_init(void)
{
    /* use OC1A pin as output */
    DDRD = _BV(PD5);

    /*
    * clear OC1A on compare match
    * set OC1A at BOTTOM, non-inverting mode
    * Fast PWM, 8bit
    */
    TCCR1A = _BV(COM1A1) | _BV(WGM10);

    /*
    * Fast PWM, 8bit
    * Prescaler: clk/1 = 8MHz
    * PWM frequency = 8MHz / (255 + 1) = 31.25kHz
    */
    TCCR1B = _BV(WGM12) | _BV(CS10);

    /* set initial duty cycle to zero */
    OCR1A = 0;

    /* Setup Timer0 */

    TCCR0|=(1<<CS00);
    TCNT0=0;
    TIMSK|=(1<<TOIE0);
    sample_count = 4;
    sei(); //Enable interrupts
}

ISR(TIMER0_OVF_vect)
{

         sample_count--;
         if (sample_count == 0)
            {
             sample_count = 4;
             OCR1A = pgm_read_byte(&pcm_samples[sample++]);
            if(sample>pcm_length)sample=0;
            }
}

int main(void)
{
   pwm_init();
   while(1);//do nothing
}

The header file which plays "its working":

// pcm samples created by wav2c
//It plays "its working"

const long pcm_length=6800;

const unsigned char pcm_samples[] PROGMEM ={
   116,97,144,26,0,0,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,127,128,128,127,128,127,127,128,127,127,128,127,128,128,127,128,127,127,127,127,127,127,127,127,127,127,127,127,127,128,127,127,128,127,128,127,127,128,127,128,128,128,128,128,128,130,129,128,132,129,127,133,127,128,131,127,128,131,129,127,132,130,128,132,129,130,131,137,138,130,140,135,128,137,130,126,130,124,125,126,121,124,122,119,
   121,120,117,118,121,118,120,123,126,131,134,141,144,146,149,148,148,146,142,139,136,131,127,123,115,102,89,74,62,56,94,96,84,149,146,137,183,172,153,166,145,123,127,108,101,108,107,115,121,135,150,154,167,173,166,169,158,142,135,123,116,112,115,120,123,135,142,144,150,148,141,136,125,113,104,92,87,82,80,89,94,104,120,126,138,154,159,157,161,160,145,143,139,129,128,130,128,133,141,140,
   147,151,148,142,137,115,84,86,50,33,66,69,68,106,142,138,171,191,177,181,173,150,140,135,116,112,119,115,118,133,141,147,161,168,166,164,163,152,137,133,123,112,110,106,92,86,92,74,67,82,93,107,111,137,151,142,159,160,151,151,143,136,136,127,126,131,127,134,139,141,152,157,163,168,165,161,152,140,123,107,85,73,68,42,40,57,74,93,110,147,159,166,182,180,171,164,150,134,130,116,
   112,118,118,125,135,146,159,170,178,181,177,170,155,137,118,99,78,68,62,43,37,45,61,91,107,129,162,167,173,186,176,166,158,141,131,120,112,112,114,121,131,140,156,169,178,188,184,180,170,150,133,113,91,75,69,56,40,39,45,62,94,108,127,164,165,171,187,174,167,157,140,132,118,111,115,115,124,136,146,162,177,186,190,188,180,166,145,125,104,81,72,61,40,34,33,42,73,90,107,143,
   156,165,182,182,178,170,156,146,132,119,117,115,119,126,134,149,162,174,183,185,184,175,161,144,123,103,84,74,62,44,37,41,54,77,88,113,147,141,159,181,169,173,171,160,153,136,131,131,121,125,132,133,143,152,163,168,166,171,165,149,139,125,108,93,90,87,76,73,74,82,90,91,102,114,117,121,133,140,144,149,152,153,148,144,144,142,140,139,142,144,143,146,147,144,141,140,135,130,127,125,
   123,120,121,123,121,118,116,115,115,114,112,112,111,110,111,112,114,117,120,124,128,130,133,135,136,137,139,141,143,144,143,143,142,140,139,138,136,135,134,133,132,132,131,131,130,129,128,127,126,125,123,122,120,117,115,114,112,111,111,112,114,115,117,120,122,124,126,129,131,133,135,136,138,139,139,139,139,138,138,137,136,135,134,133,132,132,131,130,129,128,128,127,127,126,125,125,124,123,123,122,
   122,122,122,122,122,122,123,124,124,125,126,127,128,128,129,130,130,130,131,131,131,131,131,130,130,130,130,129,129,129,129,129,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,129,129,129,129,129,129,129,129,128,128,128,128,128,128,128,128,128,128,128,128,128,127,127,127,127,127,127,127,127,127,127,127,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,129,129,129,129,129,129,129,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,129,128,127,129,
   130,128,127,128,128,127,127,128,128,127,128,128,128,128,128,128,128,128,128,128,128,128,127,128,128,128,128,128,127,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,127,128,128,128,128,128,128,128,128,128,128,129,128,128,128,128,128,128,129,129,127,128,128,127,128,128,128,128,128,128,128,128,128,128,128,128,128,127,128,128,128,128,128,129,128,127,128,128,
   127,129,128,129,129,128,128,127,129,127,128,127,127,128,128,129,128,129,128,128,128,128,128,127,128,128,128,128,128,130,128,129,127,128,128,127,127,128,129,127,129,128,129,128,127,128,128,126,130,129,127,127,128,128,128,126,129,129,128,128,129,129,128,127,128,129,128,126,128,128,129,127,130,128,129,125,129,127,127,129,126,131,125,131,128,130,126,130,126,127,128,129,129,129,126,128,130,125,129,127,
   129,126,128,124,129,129,130,131,125,126,128,129,126,130,127,130,129,126,130,127,125,125,130,128,127,129,127,131,125,127,129,128,128,127,128,127,130,126,126,125,127,129,129,130,128,130,126,130,128,131,130,128,128,125,129,126,130,127,130,130,127,128,128,130,127,130,126,130,130,125,128,128,130,129,128,125,127,130,125,129,127,129,132,128,127,126,130,126,128,129,127,130,127,128,127,128,126,127,131,126,
   129,126,124,131,128,127,128,129,127,130,127,123,133,127,129,132,127,129,128,128,124,129,126,127,131,123,129,131,130,130,128,129,129,129,121,128,130,126,130,126,127,132,130,125,129,130,125,129,123,124,132,128,125,129,129,128,131,129,124,129,129,127,130,127,128,132,129,125,128,130,127,126,128,129,127,126,127,128,129,126,127,130,130,129,126,129,130,127,128,127,128,129,128,128,130,130,127,128,128,128,
   129,127,126,128,130,127,128,129,129,129,127,128,128,127,127,127,129,128,129,129,129,128,126,128,127,126,129,129,128,129,129,128,128,128,127,128,127,128,128,127,127,128,129,128,128,127,128,129,128,128,127,127,128,129,128,128,128,128,129,128,128,128,129,129,128,128,128,127,127,128,128,128,129,128,127,128,129,128,128,127,127,129,129,128,127,127,128,129,129,128,128,129,129,128,128,129,127,128,128,128,
   128,128,128,128,128,128,128,127,127,127,128,128,127,128,128,128,127,126,128,128,129,128,128,128,129,128,129,129,128,129,129,128,128,128,129,129,128,128,128,129,128,128,127,128,128,129,128,127,127,127,127,128,128,128,128,128,127,128,128,128,128,128,127,127,128,129,128,128,128,128,128,128,129,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   127,127,128,128,128,128,128,128,128,129,128,128,128,128,129,128,128,128,128,128,128,128,129,128,128,128,128,128,127,127,127,128,128,128,128,128,127,127,128,129,129,128,128,128,128,129,129,129,128,128,129,129,129,129,128,128,128,128,128,128,128,128,128,127,128,128,127,127,127,127,127,127,127,128,128,128,128,128,128,128,128,128,128,128,128,129,129,129,129,129,129,129,129,129,129,129,128,128,128,129,
   129,128,128,128,127,127,128,128,127,127,127,127,127,127,127,127,127,127,127,127,127,128,128,128,129,129,129,129,129,128,129,129,129,130,129,128,128,129,129,129,129,129,128,128,128,128,128,128,127,127,127,127,127,127,127,127,127,127,127,126,126,127,127,127,127,128,128,128,128,129,130,130,130,130,130,130,130,130,130,130,130,129,129,129,129,129,129,128,127,125,125,125,125,124,124,124,124,125,125,125,
   125,125,126,127,128,129,129,130,130,131,132,132,132,132,132,133,133,133,133,132,131,131,131,131,130,129,128,126,124,124,124,123,122,121,119,118,119,121,121,121,122,124,126,129,132,133,134,134,135,135,137,138,139,139,138,137,138,139,139,139,137,133,130,129,128,127,123,117,111,107,104,101,98,93,89,92,105,123,138,145,146,143,140,141,146,150,146,137,129,125,127,136,147,154,155,152,149,147,145,144,
   141,133,123,115,110,107,105,102,95,84,75,75,88,111,132,146,153,152,145,140,142,144,141,136,131,123,117,121,133,143,151,155,154,148,144,144,145,144,139,131,120,112,111,115,119,119,113,99,85,76,72,83,109,135,148,152,149,145,143,148,152,147,135,123,115,115,126,141,150,150,147,145,145,149,154,153,142,129,120,115,117,122,124,120,112,104,94,88,84,80,85,105,129,144,151,152,149,145,145,146,
   140,129,119,115,117,127,140,148,148,145,145,147,149,150,146,136,125,120,121,123,125,126,123,118,114,110,103,94,84,74,81,108,138,153,154,149,146,146,151,154,143,124,111,111,121,135,147,149,142,138,144,153,156,152,141,127,118,119,126,129,124,119,117,119,122,121,111,94,82,72,75,98,130,147,144,139,142,151,156,156,143,122,107,110,125,136,140,139,138,139,148,159,160,148,135,128,126,128,130,128,
   122,118,123,131,133,128,118,107,97,91,82,77,90,119,142,147,146,147,152,153,152,144,126,111,109,120,130,135,136,138,141,148,155,156,146,135,129,129,129,128,124,120,118,124,132,134,129,121,114,107,100,90,76,73,97,132,150,147,141,145,154,158,152,137,117,106,113,128,136,134,133,139,148,156,159,151,138,130,131,134,129,121,117,118,124,132,136,133,125,120,118,114,102,89,75,67,84,120,150,149,
   137,138,155,164,156,137,116,106,109,124,133,131,128,137,152,161,158,149,141,135,134,135,130,120,115,121,131,135,134,132,132,131,130,124,112,98,87,83,77,82,106,139,152,146,143,153,162,154,137,120,110,109,116,127,131,131,137,150,159,157,149,142,137,133,128,125,121,118,121,128,134,134,133,133,134,130,123,115,106,98,91,85,77,80,106,142,158,149,140,148,161,157,137,117,108,110,119,130,134,133,
   138,153,164,160,145,136,136,136,130,123,120,121,126,133,137,136,132,132,134,132,123,113,106,102,99,94,86,78,86,118,152,159,142,134,146,160,150,125,108,107,115,124,131,134,136,144,156,162,153,138,132,135,135,128,120,120,126,133,137,137,136,134,136,136,131,121,112,110,109,106,99,93,87,87,107,139,158,148,133,137,153,156,133,111,108,118,125,126,130,136,143,150,155,152,140,131,132,135,131,121,
   118,126,134,136,133,133,136,136,133,128,122,116,112,112,109,105,100,97,92,90,109,140,159,147,132,136,154,156,133,112,111,122,129,130,131,136,144,151,154,148,137,131,134,136,130,121,122,131,137,134,131,132,136,135,130,124,120,117,114,111,106,104,101,98,89,88,111,146,159,141,127,139,159,155,126,108,113,127,131,127,128,138,147,153,152,145,136,134,138,137,128,119,124,134,139,134,132,135,139,137,
   129,123,120,118,116,112,107,102,100,98,91,90,113,146,156,138,127,141,159,151,123,108,116,128,128,125,127,136,146,151,149,141,133,134,139,135,125,120,128,136,136,130,130,136,138,134,128,124,121,118,114,110,106,103,100,95,87,94,123,151,151,133,131,151,162,144,119,113,124,131,127,124,129,139,148,150,146,139,137,141,140,131,123,125,132,133,129,128,133,137,136,132,129,125,121,117,112,107,103,100,
   96,87,84,104,136,151,138,129,143,163,156,130,117,123,131,128,121,122,131,142,149,147,140,139,146,147,138,126,126,132,134,129,126,129,134,137,135,131,126,125,123,118,109,104,103,100,91,83,93,122,144,139,128,137,157,160,141,125,124,131,130,123,118,122,134,143,143,138,138,146,149,142,131,129,133,133,128,125,126,131,134,133,130,127,127,127,123,115,109,108,105,98,89,90,109,131,134,127,130,147,
   158,149,135,131,135,136,130,122,120,128,137,138,134,134,142,147,144,137,134,135,134,131,127,125,126,129,131,129,126,127,129,126,120,116,115,113,108,103,99,103,115,125,125,123,130,142,146,140,136,137,140,137,130,126,127,130,132,131,129,132,137,139,137,134,135,135,134,130,128,127,127,128,128,126,126,127,128,126,124,124,124,123,121,120,120,120,120,121,122,124,125,126,126,128,129,129,129,129,130,130,
   129,129,129,129,129,129,129,129,130,130,130,130,130,130,130,130,130,130,130,130,129,129,128,128,128,127,127,127,127,127,127,127,127,127,127,127,127,128,128,128,128,128,128,128,129,129,129,129,129,129,129,129,129,129,129,129,129,129,129,129,129,129,128,128,128,128,128,128,128,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,127,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,131,132,129,126,126,127,127,127,127,127,128,128,129,129,129,128,129,129,129,140,124,114,133,131,119,128,133,124,123,127,143,130,117,143,133,116,132,134,
   118,124,131,127,130,127,125,130,131,126,128,131,125,126,130,126,125,129,128,125,129,128,126,128,128,127,127,129,129,129,127,127,128,130,132,127,127,129,126,127,130,127,126,129,128,127,129,129,127,129,128,131,135,128,128,130,127,126,127,126,125,127,127,127,128,128,128,129,129,127,128,128,127,127,126,127,127,127,128,127,128,128,129,129,129,129,129,129,129,130,129,130,130,129,129,129,129,129,129,129,
   129,128,128,128,127,127,127,126,126,126,125,126,125,124,125,123,123,125,123,124,126,124,127,128,128,130,130,131,133,132,133,134,133,134,134,133,134,134,133,134,133,133,133,131,131,131,128,129,127,125,125,122,121,120,117,117,115,112,113,112,111,114,113,116,121,121,127,132,134,140,142,143,147,146,146,146,144,143,142,139,140,139,138,139,139,138,139,136,135,133,129,125,120,114,108,102,95,91,85,84,
   87,88,98,105,112,127,133,142,153,152,157,157,151,151,144,139,137,132,131,133,134,139,145,147,152,154,153,153,148,143,138,131,125,119,115,111,108,108,106,104,103,97,94,93,93,94,99,105,109,120,127,135,147,150,154,158,153,152,149,141,139,134,129,131,131,132,138,140,144,148,148,148,148,143,139,137,129,127,124,119,119,116,114,115,113,111,108,102,97,94,92,91,96,101,108,118,126,136,146,150,
   156,156,154,152,146,141,136,131,129,128,130,133,137,142,146,149,152,150,150,146,141,138,131,127,124,118,118,115,113,115,113,111,109,103,98,95,91,91,94,97,106,113,123,133,141,149,153,155,155,151,149,143,139,136,132,132,133,135,140,143,147,150,151,151,149,146,141,136,131,126,122,118,115,113,112,111,110,109,106,102,96,93,91,91,96,100,107,117,124,135,143,149,154,155,153,151,147,143,139,135,
   134,134,135,138,141,144,148,150,150,150,147,143,140,134,129,127,122,120,119,115,116,115,111,113,109,104,102,95,93,93,93,99,105,112,121,129,138,143,148,151,149,150,146,141,141,135,134,135,133,138,140,142,147,148,148,149,147,145,142,138,133,130,127,123,123,121,119,120,116,115,116,109,107,104,94,95,91,90,98,100,110,119,125,136,141,145,150,148,147,146,141,139,136,134,135,134,137,141,143,147,
   149,150,151,148,146,143,138,135,131,127,126,123,122,122,121,120,118,116,114,110,106,101,96,94,91,94,98,102,112,119,127,136,140,144,147,146,146,144,140,139,136,135,136,136,138,141,143,147,149,150,150,148,146,143,138,135,131,127,126,124,123,123,121,121,120,117,115,111,107,102,97,94,91,91,95,101,107,117,124,131,139,142,145,147,144,144,142,138,138,135,135,137,138,141,145,146,149,151,150,150,
   147,143,140,136,132,129,126,125,123,122,123,121,121,121,118,115,112,106,101,97,92,92,92,96,104,109,119,127,132,141,143,145,147,143,142,140,136,136,135,134,137,138,141,145,147,150,151,150,149,146,143,140,135,132,129,126,125,124,123,124,123,122,121,120,116,113,108,102,100,95,94,95,96,103,108,115,123,128,135,139,141,144,142,142,140,138,137,135,136,137,137,141,142,145,148,148,149,148,145,144,
   140,137,135,130,129,127,125,127,125,124,124,122,121,120,116,114,110,105,103,99,98,98,99,103,108,113,120,126,130,136,138,139,141,139,139,138,135,136,136,135,139,139,141,145,145,148,148,147,147,144,142,140,136,134,131,129,128,127,126,125,124,123,122,121,119,117,114,110,106,102,99,98,98,100,104,108,114,120,125,130,134,137,139,140,139,139,138,137,137,136,137,138,140,142,144,146,147,147,147,146,
   144,142,139,136,133,131,129,128,127,127,126,125,124,123,122,120,118,115,111,108,105,101,100,100,100,104,107,112,118,122,128,132,134,137,138,138,139,137,137,137,136,137,138,139,142,143,144,146,146,147,146,144,143,140,137,135,132,130,129,128,127,126,126,125,123,122,121,119,117,114,110,107,104,102,100,100,102,106,109,114,119,123,128,131,134,137,137,138,137,137,137,136,137,138,138,141,141,143,145,145,
   146,145,144,144,141,139,137,135,133,131,130,129,128,128,127,125,124,123,121,120,117,115,112,108,106,103,102,102,103,105,108,112,116,120,125,128,132,134,136,137,138,138,138,138,138,139,139,140,141,142,143,144,144,144,144,143,142,140,138,136,134,132,131,130,129,128,127,126,125,123,122,120,118,116,114,111,108,105,104,103,103,104,107,110,114,118,122,126,130,133,135,137,138,138,138,138,138,139,139,140,
   140,141,143,143,144,144,144,143,142,141,139,137,135,133,131,130,129,128,128,127,126,124,123,122,120,118,115,112,109,107,104,103,102,103,106,109,112,116,121,125,129,132,134,136,137,137,137,137,137,138,138,139,140,141,142,143,143,144,144,143,142,141,139,137,135,134,132,130,129,129,128,128,127,126,125,123,122,119,117,115,111,109,107,104,103,103,104,107,110,114,118,122,126,130,132,134,136,136,137,137,
   137,137,137,138,139,140,141,142,143,143,144,144,143,142,140,138,137,135,133,131,130,129,129,128,128,127,126,125,123,121,119,117,114,112,109,107,106,106,105,106,108,112,115,118,122,125,128,131,133,134,135,136,136,137,137,137,138,139,140,140,141,142,142,143,142,142,141,139,138,136,135,133,132,131,130,129,128,128,127,126,125,123,122,120,118,116,114,112,110,108,107,106,107,108,110,113,117,120,124,128,
   131,133,134,135,136,137,137,137,137,137,138,139,139,140,141,142,142,142,142,141,140,138,137,135,134,132,131,130,129,129,128,128,127,126,124,123,121,120,117,115,113,111,109,108,107,107,108,110,112,115,119,122,125,128,131,133,134,135,136,136,136,137,137,137,138,139,140,141,142,142,142,142,141,141,139,138,136,135,133,132,130,129,129,128,127,126,125,124,123,121,119,117,115,113,111,109,108,108,108,109,
   110,113,116,119,123,126,129,131,133,134,135,136,136,136,136,137,137,138,139,140,141,142,142,142,142,141,140,139,137,136,134,132,131,129,128,128,127,126,125,124,123,122,121,119,117,114,113,111,110,109,109,109,110,111,114,118,121,124,127,130,132,134,135,135,136,137,137,137,137,138,138,139,140,141,142,142,142,141,140,139,137,136,134,132,131,129,128,127,127,126,125,124,123,122,121,120,118,116,115,113,
   112,112,111,111,112,113,114,116,119,122,125,128,130,132,134,135,136,137,138,138,138,139,139,140,140,141,141,141,141,140,140,139,137,136,134,132,130,129,127,126,125,124,123,122,121,120,119,118,116,115,114,113,113,112,113,113,114,116,118,120,123,125,128,130,132,134,135,136,137,138,138,139,139,139,139,140,140,140,140,140,139,139,137,136,135,133,131,129,128,127,126,125,124,123,123,123,122,121,119,118,
   117,116,114,114,114,114,114,115,116,117,120,122,124,126,128,130,132,133,135,135,136,137,138,138,139,139,140,140,140,140,140,140,139,138,137,135,133,132,130,129,127,126,125,124,123,122,121,120,120,119,118,117,116,116,115,115,115,115,116,117,119,121,123,126,128,130,132,133,134,135,136,136,137,137,137,137,137,138,138,138,138,138,138,137,136,135,134,132,131,129,128,127,126,125,124,124,123,123,122,121,
   121,120,119,119,118,118,118,118,118,119,119,120,122,123,125,126,128,129,130,131,132,133,134,134,135,135,136,136,136,137,137,137,137,136,136,136,135,134,133,132,131,130,129,128,127,126,125,124,123,123,123,122,121,121,120,120,119,119,119,119,120,120,120,120,122,123,124,126,127,129,130,131,132,132,133,134,134,134,135,135,135,136,136,136,136,136,135,135,134,133,133,131,130,129,128,127,127,126,125,125,
   125,124,124,124,124,124,124,123,122,122,121,121,121,121,121,122,122,123,125,126,127,128,129,130,130,130,131,131,131,131,132,132,132,133,133,133,133,134,133,133,133,132,131,131,130,130,129,128,128,128,127,127,127,127,126,126,126,126,126,125,125,124,124,123,123,123,123,123,123,124,124,125,126,127,128,128,128,128,129,129,129,129,130,130,130,131,131,132,132,133,133,133,133,132,132,131,130,130,129,129,
   128,128,128,128,128,128,128,128,128,127,127,126,126,125,125,125,125,125,125,125,125,125,126,126,127,127,128,128,128,128,128,128,128,128,128,128,128,129,129,129,129,129,130,130,130,130,130,130,129,129,129,129,128,128,129,129,129,129,129,129,129,128,128,128,128,128,128,127,127,126,126,126,126,126,127,127,127,127,127,127,127,127,127,128,128,128,128,128,128,128,128,129,129,129,129,129,129,129,129,129,
   128,128,128,128,128,128,128,128,128,129,129,129,128,128,128,128,128,127,128,128,128,128,128,128,128,128,127,127,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,
   128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,128,

};

Regards,

Rejith
Thiruvananthapuram, India.

Feedback and comments are welcome. Thank you!

60 comments:

Avinash GuptaNovember 19, 2010 at 6:07 PM
You didn't mention the playback time achievable. I made the same thing. With uncompressed raw 8K samples per second with 8 bit sample we get a 8KBps audio. That means if allocate 3/4th of ATmega32's flash to audio sample storage we can get a 3sec audio clip. The time constraints make this fairly unusable.
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RejithNovember 20, 2010 at 9:39 PM
Yeah. It would require more memory to play large audio clips. However, adding some serial EEPROM like AT24c1024 could provide about 16sec of audio.
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FredDecember 14, 2010 at 2:19 AM
Hi. What ohm speaker did you use and how "loud" was the sound produced? Thanks
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RejithDecember 20, 2010 at 1:36 AM
An 8ohm speaker would sound but quite feeble. You would probably require a low pass filter and a small amplifier for better and louder sound.
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menotmeJanuary 28, 2011 at 2:55 AM
I am trying to repeat but I only get static ish noise. what speaker and low pass values did you use?
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RejithFebruary 13, 2011 at 8:59 AM
Speaker is not a real issue here. However, you may require any low pass filter and an amplifier circuit to hear it clearly. Connect the OC1A output directly to any amplifier using a 0.1uf capacitor and you must surely hear something unless there is some problem in the assembly.
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UnknownApril 5, 2011 at 1:58 AM
Hello.
Can anyone give me the code of pgm_read_byte() function please?
Thank you very much. iker @ leako . com
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RejithMay 1, 2011 at 1:00 AM
pgm_read_byte()is used to retrieve data specifically from the flash memory. The compiler used is win GCC avr.
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vinothJune 6, 2011 at 12:39 AM
can you tell me what is the period of timer interrupt
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RejithJune 23, 2011 at 11:59 AM
Which timer interrupt period you mean? The PWM is done at 31.25khz.
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SimsimOctober 28, 2011 at 11:11 PM
I simulate in proteus like attached picture, but only hissing noise. Did any one tried it in hardware? Plz inform me by "krp.eee@gmail.com"
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SimsimOctober 29, 2011 at 12:45 AM
i tried to simulate it in proteus but only hissing noise. any solution informed me plz at "krp.eee@gmail.com"
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RejithNovember 20, 2011 at 2:03 AM
hi krp,

This won't work in proteus. I had tried that and it produces hissing sound. proteus seems not good at simualating sounds..It works fine on hardware though
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Ayush SinhaMarch 20, 2012 at 9:08 AM
"Its working!" , but there is a hissing sound at the beginning.
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RejithMarch 24, 2012 at 11:11 PM
The hissing sound can be eliminated by filtering the unwanted data at the beginning and the end, the values 128. The beginning wave can be ramped by sending values starting from 0 to 128 before the data, and 128 to 0 after the data.
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farhadMay 28, 2012 at 5:14 AM
how to change it into codevision compatability?

#include
#include
#include
#define SAMPLE_RATE 8000

unsigned int sample=0;
int sample_count;

void pwm_init(void)
{

DDRD=0x21;
PORTD=0x00;

TCCR1A=0x81;
TCCR1B=0x09;
OCR1A=0x00;
TCCR0=0x69;
TCNT0=0x00;
TIMSK=0x01;

sample_count=4;

}

interrupt [TIM0_OVF] void timer0_overflow(void)
{
sample_count--;
if (sample_count==0)
{
sample_count=4;}

OCR1A=pcm_samples[sample++];
if (sample>pcm_length)
{sample=0;
TCCR0=0x00;
PORTD=0x01;
}
}
void main (void)
{
#asm("sei");
pwm_init();
while(1);

}

_________
but its making beeps with hissing sounds and my proteus file is just like the same
how to define bitrate for this wave file? is it 64kbit/s wav file?
please explain me the sample_count=4, why 4??
I need to understand baud, bit rate of this example..
do we need to put delay_us(); function to optimize speed either?
Hope Rejith will answer me,hehe. Thanks:))
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farhadMay 28, 2012 at 5:16 AM
its also used for mega32..
but donno why library did not pasted in post.
Regards,
Farhad
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farhadMay 30, 2012 at 10:44 AM
I wrote this in main:
OCR1A=(*((unsigned char flash *)(&pcm_samples[sample++])));
and this in .h file:
unsigned char flash pcm_samples[]={
_______
yet does not work
the code u have for GCC works fine, but the code I translated to codevision does not work:((
sad..
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RejithJune 12, 2012 at 7:23 AM
@Farhad
The wav file should be mono 8000 samples/sec. Convert any wav file to 8000, mono 8-bit using switch software. The sample_count will vary the speed of speech. delay functions are not used here.

In codevision, you have to make sure whether the code for retrieving sample data from flash is actually working.
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CandelectrónicaJuly 5, 2012 at 1:42 PM
What is the period of Timer 0?
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mayank sinhaSeptember 10, 2012 at 5:31 AM
Hey Rejith,
i tried playing ur code on ATmega32 using a 2 Watts,8 ohm speaker but could not achieve desired audio.
Actually it is required to play the audio for "thank you" and "sorry" in my application, as directed by ur link above, i converted 'text' into 'speech' .wav file using ATnT, then converted it to 8000samples, mono 8bit .wav file using 'switch', then converted it to c code and obtained the values...
Issue is that audio is not clear n hissing noise is observed.
i tried connecting speaker to micro-controller using RC filter but couldnt get desired audio,
i built an op-amp audio amplifier circuit using LM358 (refer this : http://www.techlib.com/electronics/audioamps.html#op-amp)
kindly look into the matter and suggest the needful step for playing those files on ATmega 32.

Thanks and regards
Mayank Sinha
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UnknownOctober 19, 2012 at 9:33 AM
How do we just plop the wav data into the main.c? so that it doesn't have to be external? in pcm_samples.h? I'm trying this on a AVR32 but its not quite working.
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git_pullFebruary 19, 2013 at 12:39 AM
yes i did it using atmega8 just change the line
DDRB = _BV(PB1);

the audio "its working" is playing fast so to reduce speed do
sample_count=8
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UnknownMarch 1, 2013 at 2:37 PM
Well, I used your project as a part of my project ;) but after playing my sample I'm getting rather loud, crashy noise, which does not depend on the length of the sample. Any ideas what might that be?
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RachmanboboMarch 12, 2013 at 8:57 PM
cool..... remind me old school with sound blaster 8 bit experience :-)
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deddmitrichMarch 30, 2013 at 2:58 PM
cool device =)
8bit rulez come to my blog
www.great8bit.blogspot.com
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UnknownApril 20, 2013 at 8:42 PM
i am confused with step 2 and 3. how do i convert the wav file into 8 bit 8000sample/sec wav file?well i've downloaded the software but couldn't find the option. and the zip file only contains a c program file and an exe file.
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electrobuzJune 14, 2013 at 4:37 AM
I am not able to do step 3. That is my 8kbps wav file is not converting to C code (samples). Appreciate any help on how to use wav2c exactly.
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AnonymousSeptember 8, 2013 at 11:48 PM
Hello can i upload this to the microcontroller? sorry i am newbie. and, can i upload multiple wav file in 1 microcontroller? please help me thanks.
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AnonymousSeptember 8, 2013 at 11:49 PM
How can i upload the wav file in the microcontroller?
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UnknownOctober 24, 2013 at 12:56 AM
Rejith, can you help me ?
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UnknownMarch 12, 2014 at 12:08 PM
Does anybody know How to store and play PCM audio messages from SD card via AVR mic' ? I do not want to use FatFs.
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UnknownJune 7, 2014 at 5:57 AM
Rejith sir, can u tell wats maximum secs of sound can be stored in Atmega 32, my objective is to produce sound of colors wen the different leds blink specifically.
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UnknownJuly 6, 2014 at 4:24 PM
What program do I use to upload the code to my ATtiny85? Also, do I have to save the header file (pcm_sample.h) in a specific directory when uploading it?
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UnknownDecember 20, 2014 at 10:06 PM
With 1K and 01.1uF filter, lot of hissing noice. why?
Eugene
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UnknownDecember 20, 2014 at 10:06 PM
Sorry. It was 1K and 0.1uF
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HartmutJune 14, 2015 at 5:12 AM
Hello Rejith,

cool stuff, thank you. To suppress the click at every end-of-pcm-data I changed

if(sample>pcm_length)sample=0;

to

if(sample>=pcm_length)sample=0;

Hartmut
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UnknownJuly 8, 2015 at 1:10 AM
This comment has been removed by the author.
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UnknownJuly 20, 2015 at 3:18 AM
This comment has been removed by the author.
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mamang_hendryNovember 24, 2015 at 11:14 PM
Use DAC R2R ladder Is better . it works
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UnknownDecember 30, 2015 at 12:30 AM
hi,
i dnt know how to Convert the 8 bit wav file to a sample c file using that software(wav2c). please give some idea
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abhayMay 11, 2016 at 8:19 AM
hi how to use the wav2c because when i compiled (wave2c exe ,main.o wavedata.o files) are generated let me where i will get my c source bytes which will dump into avr and dataflash or suggest me some trick what should i do i tried it lot of times
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UnknownSeptember 13, 2016 at 10:11 PM
This comment has been removed by the author.
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UnknownSeptember 13, 2016 at 10:13 PM
Thank you.
How do I modify this for atmega328?I have tried it and I get a hissing sound.
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UnknownNovember 26, 2016 at 3:46 AM
can anyone share the c code to play audio from eprom
thanks
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UnknownMarch 12, 2017 at 6:12 AM
thanks for your great work
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UnknownJune 8, 2018 at 11:42 AM
@Rejith gracias por el ejemplo. Estoy tratando de implementarlo para un atmega2560 se escucha parte del sonido y se escucha claro, pero pareciera que se cicla y no termina de reproducir todo el audio. he modificado la salida del audio a DDB5 y todo bien, lo que no entiendo es porque se cicla el sonido, como si la interrupcion de desbordamiento se ejecutara muy rapido. espero me puedas ayudar gracias!!
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UnknownNovember 27, 2018 at 9:55 PM
Great Tutorial!!!
I've been trying to look out for the wav2c a long time, and yours works just so perfect, I'm working with my arduino uno creating some crazy sounds, I use audacity to covert the mp3 to wav with 8000hz and 8 bit sound, hopefully I can get more space for more sound, maybe with SD card support!!
Again, thanks for sharing this info!
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