DSP - SMiW

/*****************************************************************************
**                                                                          **
**   Name:  BF537 C Talkthrough I2S                                     **
**                                                                          **
******************************************************************************
Analog Devices, Inc.  All rights reserved.

File Name:  Main.c

Date Modified:  12/14/04        Rev 1.0
        01/11/05        Rev 1.1 Updated to work on Rev 1.1 of the ADSP-BF537 EZ-Kit

Hardware:   ADSP-BF537 EZ-KIT Board Rev 1.1
            Users of ADSP-BF537 EZ-KIT Board Rev 1.0 must change the SPORT to
            generate internal clock and frame sync

Purpose:    This program sets up the ADSP-BF537 to reset the ADC and DAC.
            The data to/from the DAC/ADC are transfered over SPORT0 in I2S mode.

Program Parameters:


******************************************************************************/
#include "Talkthrough.h"
#include <sysreg.h>
#include <ccblkfn.h>


/*****************************************************************************

Variables

Description:    The variables ChannelxLeftIn and ChannelxRightIn contain
        the data coming from the codec ADC (AD1871).  The (processed)
        playback data are written into the variables
        ChannelxLeftOut and ChannelxRightOut respectively, which
        are then sent back to the DAC (AD1854) in the SPORT0 ISR.

******************************************************************************/
// left input data from AD1871
int iChannel0LeftIn, iChannel1LeftIn;
// right input data from AD1871
int iChannel0RightIn, iChannel1RightIn;
// left ouput data for AD1854
int iChannel0LeftOut, iChannel1LeftOut;
// right ouput data for AD1854
int iChannel0RightOut, iChannel1RightOut;
// SPORT0 DMA transmit buffer
int iTxBuffer1[2];
// SPORT0 DMA receive buffer
int iRxBuffer1[2];

int delayMilliseconds = 500; // half a second
int delaySamples;  // assumes 44800 Hz sample rate
float decay = 0.5f;
int buffer[5000];
int current = 0;

//--------------------------------------------------------------------------//
// Function:    main                                                        //
//                                                                          //
// Description: After calling a few initalization routines, main() just     //
//              waits in a loop forever.  The code to process the incoming  //
//              data can be placed in the function Process_Data() in the    //
//              file "Process_Data.c".                                      //
//--------------------------------------------------------------------------//
void main(void)
{
    delaySamples  = (int)((float)delayMilliseconds * 44.8f);
    Init_Flags();
    Audio_Reset();
    Init_Sport0();
    Init_DMA();
    Init_Interrupts();
    Enable_DMA_Sport0();

    while(1);
}

//////////////////////////////////////////////////////////////////

#include "Talkthrough.h"
extern float decay;
extern int delaySamples;
extern int current;
extern int buffer[];

//------------------------------------------------------------------//
// Function:    Process_Data()                                              //
//                                                                          //
// Description: This function is called from inside the SPORT0 ISR every    //
//              time a complete audio frame has been received. The new      //
//              input samples can be found in the variables iChannel0LeftIn,//
//              iChannel0RightIn, iChannel1LeftIn and iChannel1RightIn      //
//              respectively. The processed data should be stored in        //
//              iChannel0LeftOut, iChannel0RightOut, iChannel1LeftOut,      //
//              iChannel1RightOut, iChannel2LeftOut and iChannel2RightOut   //
//              respectively.                                               //
//--------------------------------------------------------------------------//
void Process_Data(void)
{
    int i;

    buffer[current] = iChannel0LeftIn;

    for (i = 0; i < 5000; i++)
    {
        buffer[i] += (int)((float)iChannel0LeftIn * decay);
    }

    iChannel0LeftOut = buffer[current];
    iChannel0RightOut = iChannel0LeftOut;

    if(current++ >= 5000){
        current = 0;
    }
}