custom sd card wav player help

[Darwin1234]

Hello,

i am implementing a simple wav player that play samples that are saved on SD card. i am using r2r 8bit DAC as output..my problem is i get a trash sounds instead of a music. definitely i check the r2r circuit and working correctly. but i am confuse why i got a trash sounds?


i actually check the output using serial communication and it gives me a hex value like 7F 7F 7F 7F with out an 0x prefixed like 0x7F 0x7F 0x7F 0x7F. do you think that's the problem???


here are my full code:

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unsigned char mmc_buf[512];
 
void uart_init(void)
{
  // Setup the UART baud rate
  UBRR0H = (BAUD_RATE_UBRR >> 8);
  UBRR0L = BAUD_RATE_UBRR;
 
  // Enable the UART receiver and transceiver
  UCSR0B = _BV(RXEN0) | _BV(TXEN0);
  // Set the frame format : 8 bits data, 1 bit stop
  UCSR0C = _BV(UCSZ01) | _BV(UCSZ00);
}
 
void uart_write(uint8_t byte)
{
  while (!(UCSR0A & (1 << UDRE0)));
  UDR0 = byte;
}
 
int uart_stream_write(char c, FILE *stream)
{
  if (c == '\n')
    uart_stream_write('\r', stream);
 
  uart_write(c);
  return 0;
}
 
static FILE uart_stdout = FDEV_SETUP_STREAM(uart_stream_write, NULL, _FDEV_SETUP_WRITE);
 
/*****************************************************************************
* MMC functions
******************************************************************************/
 
#define MMC_CMD_SIZE 6
uint8_t mmc_cmd[MMC_CMD_SIZE];
 
#define MMC_TIMEOUT  0xFF
#define MMC_BLOCK_SIZE 512
 
#define DDR_CS  DDRB
#define PORT_CS PORTB
#define DD_CS   DDB2
 
#define SET_CS()   PORT_CS |= _BV(DD_CS);
#define CLEAR_CS() PORT_CS &= ~_BV(DD_CS);
 
uint8_t mmc_response(uint8_t response)
{
  uint16_t count = 0xFFF;
  uint8_t result;
 
  while(count > 0)
  {
    result = spi_receive_byte();
    if (result == response)
      break;
    count--;
  }
 
  if (count == 0)
    return 1; /* Failure, loop was exited due to timeout */
 
  return 0; /* Normal, loop was exited before timeout */
}
 
void mmc_init(void)
{
  uint8_t i;
  uint8_t byte;
 
  /* Init the CS output */
  DDR_CS |= _BV(DD_CS);
 
  SET_CS();
  {
    /* Init the card in SPI mode by sending 80 clks */
    for(i = 0; i < 10; i++)
      byte = spi_receive_byte();
  }
  CLEAR_CS();
 
  printf("send CMD0\n");
 
  /* Send CMD0 GO_IDLE_STATE */
  mmc_cmd[0] = 0x40;
  mmc_cmd[1] = 0x00;
  mmc_cmd[2] = 0x00;
  mmc_cmd[3] = 0x00;
  mmc_cmd[4] = 0x00;
  mmc_cmd[5] = 0x95;
  spi_send(mmc_cmd, MMC_CMD_SIZE);
 
  if (mmc_response(0x01))
  {
    printf("CMD0 timeout\n");
    return;
  }
 
  printf("send dummy clocks\n");
 
  /* Send some dummy clocks after GO_IDLE_STATE */
  SET_CS();
  spi_receive_byte();
  CLEAR_CS();
 
  printf("send CMD1\n");
 
  /* Send CMD1 SEND_OP_COND until response is 0 */
  i = MMC_TIMEOUT;
  do
  {
    mmc_cmd[0] = 0x41;
    mmc_cmd[1] = 0x00;
    mmc_cmd[2] = 0x00;
    mmc_cmd[3] = 0x00;
    mmc_cmd[4] = 0x00;
    mmc_cmd[5] = 0xFF;
    spi_send(mmc_cmd, MMC_CMD_SIZE);
    i--;
  } while((mmc_response(0x00) != 0) && (i > 0));
 
  if (i == 0)
  {
    printf("CMD1 timeout\n");
    return;
  }
 
  printf("send dummy clocks\n");
 
  /* Send some dummy clocks after GO_IDLE_STATE */
  SET_CS();
  spi_receive_byte();
  CLEAR_CS();
 
  printf("send CMD16\n");
 
  /* Send CMD16 SET_BLOCKLEN to set the block length */
  mmc_cmd[0] = 0x50;
  mmc_cmd[1] = 0x00;   /* 4 bytes from here is the block length */
                       /* LSB is first */
                       /* 00 00 00 10 set to 16 bytes */
                       /* 00 00 02 00 set to 512 bytes */
  mmc_cmd[2] = 0x00;
  /* high block length bits - 512 bytes */
  mmc_cmd[3] = 0x02;
  /* low block length bits */
  mmc_cmd[4] = 0x00;
  mmc_cmd[5] = 0xFF; /* checksum is no longer required but we always send 0xFF */
  spi_send(mmc_cmd, MMC_CMD_SIZE);
 
  if ((mmc_response(0x00)) == 1)
  {
    printf("CMD16 timeout\n");
  }
 
  SET_CS();
  spi_receive_byte();
 
  printf("mmc_init end\n");
}
 
void mmc_read_block(uint16_t block_number, uint8_t* block_address)
{
  uint16_t checksum;
  uint16_t varh, varl;
 
  varl = ((block_number & 0x003F) << 9);
  varh = ((block_number & 0xFFC0) >> 7);
 
  printf("read block %i\n", block_number);
 
  CLEAR_CS();
  {
    /* send MMC CMD17(READ_SINGLE_BLOCK) to read the data from MMC card */
    mmc_cmd[0] = 0x51;
    /* high block address bits, varh HIGH and LOW */
    mmc_cmd[1] = varh >> 0x08;
    mmc_cmd[2] = varh & 0xFF;
    /* low block address bits, varl HIGH and LOW */
    mmc_cmd[3] = varl >> 0x08;
    mmc_cmd[4] = varl & 0xFF;
    /* checksum is no longer required but we always send 0xFF */
    mmc_cmd[5] = 0xFF;
    spi_send(mmc_cmd, MMC_CMD_SIZE);
 
    /* if mmc_response returns 1 then we failed to get a 0x00 response */
    if ((mmc_response(0x00)) == 1)
    {
      printf("read block timeout\n");
      return;
    }
 
    /* wait for data token */
    if ((mmc_response(0xFE)) == 1)
    {
      printf("data token missing\n");
      return;
    }
 
    printf("receive block\n");
 
    /* Get the block of data based on the length */
    spi_receive(block_address, MMC_BLOCK_SIZE);
 
    /* CRC bytes that are not needed */
    checksum = spi_receive_byte();
    checksum = checksum << 0x08 | spi_receive_byte();
  }
  SET_CS();
 
  spi_receive_byte();
 
  printf("block received\n");
}
 
void audio_playback(uint8_t *block_address, uint16_t length)
{
 
  uint16_t i, j;
  uint8_t byte;
  DDRD =  255;
   
   
   
    for(j = 0; j < 4521984; j++)
    {
 
    
   
      PORTD = block_address[i * 16 + j];
       
      if(j >= 4521984){
      
          j=0;
      
      }
      
      if(i >= 512){
      
      
         i = 0;
      
      }
       
       _delay_us(64);
      
      
    }
     
 
 
}
 
/*****************************************************************************
* Main program
******************************************************************************/
uint8_t mmc_block[MMC_BLOCK_SIZE];
 
int main (void)
{
 
 
  _delay_us(125);
 
  /* Init the UART */
    uart_init();
    stdout = &uart_stdout;
 
  /* Init the SPI */
    printf("spi_init\n");
    spi_init();
 
  /* Init the MMC */
    printf("mmc_init\n");
    mmc_init();
 
  /* Reset the MMC buffer */
    memset(mmc_block, 0xCA, MMC_BLOCK_SIZE);
 
  /* Read the first block */
    mmc_read_block(645, mmc_block);
    audio_playback(mmc_block, MMC_BLOCK_SIZE);
 
  /* Infinite loop */
  for(;;);
 
  return(0);
}

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thanks in advance!