loopback.c

CHAPTER 1- real-Time Digital Signal Processing: Implementations and Applications, Second Edition by

// 
//  Project: Experiment 1.6.6 Loopback - Chapter 1 
//  File name: loopback.c   
//
//  Description: This function is an example of looping audio on the C5510 DSK.
//               This function is modified from the DSK tone example.
//
//  For the book "Real Time Digital Signal Processing: 
//                Implementation and Application, 2nd Ed"
//                By Sen M. Kuo, Bob H. Lee, and Wenshun Tian
//                Publisher: John Wiley and Sons, Ltd
//
//  Tools used: CCS v.2.12.07
//              TMS320VC5510 DSK Rev-C
//


/*
 *  Copyright 2002 by Spectrum Digital Incorporated.
 *  All rights reserved. Property of Spectrum Digital Incorporated.
 */

/*
 *  DSP/BIOS is configured using the DSP/BIOS configuration tool.  Settings
 *  for this example are stored in a configuration file called tone.cdb.  At
 *  compile time, Code Composer will auto-generate DSP/BIOS related files
 *  based on these settings.  A header file called tonecfg.h contains the
 *  results of the autogeneration and must be included for proper operation.
 *  The name of the file is taken from tone.cdb and adding cfg.h.
 */
#include "loopbackcfg.h"

/*
 *  The 5510 DSK Board Support Library is divided into several modules, each
 *  of which has its own include file.  The file dsk5510.h must be included
 *  in every program that uses the BSL.  This example also includes
 *  dsk5510_aic23.h because it uses the AIC23 codec module.
 */
#include "dsk5510.h"
#include "dsk5510_aic23.h"

/* Codec configuration settings */
DSK5510_AIC23_Config config = { \
  0x0017,  /* 0 DSK5510_AIC23_LEFTINVOL  Left line input channel volume */ \
  0x0017,  /* 1 DSK5510_AIC23_RIGHTINVOL Right line input channel volume */\
  0x01f9,  /* 2 DSK5510_AIC23_LEFTHPVOL  Left channel headphone volume */  \
  0x01f9,  /* 3 DSK5510_AIC23_RIGHTHPVOL Right channel headphone volume */ \
  0x0011,  /* 4 DSK5510_AIC23_ANAPATH    Analog audio path control */      \
  0x0000,  /* 5 DSK5510_AIC23_DIGPATH    Digital audio path control */     \
  0x0000,  /* 6 DSK5510_AIC23_POWERDOWN  Power down control */             \
  0x0043,  /* 7 DSK5510_AIC23_DIGIF      Digital audio interface format */ \
  0x0081,  /* 8 DSK5510_AIC23_SAMPLERATE Sample rate control */            \
  0x0001   /* 9 DSK5510_AIC23_DIGACT     Digital interface activation */   \
};

/*
 *  main() - Main code routine, initializes BSL and generates tone
 */

void main()
{
  DSK5510_AIC23_CodecHandle hCodec;
  Uint16 i,j;
  Int16  left,right;    
    
  // Initialize the board support library, must be called first
  DSK5510_init();

  // Start the codec
  hCodec = DSK5510_AIC23_openCodec(0, &config);
    	
  // Loop back line-in audio for 30 seconds at 48kHz sampling rate
  for (i = 0; i < 30; i++)
  {
    for (j = 0; j < 48000; j++)
    {    
      // Read a sample from the left input channel 
      while (DSK5510_AIC23_read16(hCodec, &left));
      // Read a sample from the right input channel
      while (!DSK5510_AIC23_read16(hCodec, &right));   
            
      // Write a sample to the left output channel
      while (DSK5510_AIC23_write16(hCodec, left));
      // Write a sample to the right output channel
      while (!DSK5510_AIC23_write16(hCodec, right));
    }    
  }

  // Close the codec
  DSK5510_AIC23_closeCodec(hCodec);
}