generating sine wave from PADK C6727

Sajaad Boodoo,

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INTC Module:
The interrupt module provides interrupt management services and a dispatcher.
This module is delivered as a separate library.

The INTC module in CSL3.x is designed to provide an abstraction for all the basic interrupt controller functions, such as enabling and disabling interrupts, specifying the user function to be called in response to interrupts, and setting desired hardware properties.

The EMIF EM_WAIT pin has the ability to generate an NMI (INT1) based upon a rising edge on the EM_WAIT pin. Note that while this interrupt is connected to the CPU NMI (non-maskable interrupt), it is actually maskable through the EMIF control registers. In fact, the default state for this interrupt is disabled.

Please have a look at this wiki article, it will help you for PADK,
http://processors.wiki.ti.com/index.php/Converting_from_INTC_to_BIOS#Process_for_C6727_Project

The C672x CSL provides an API for configuring and controlling the on-chip peripherals for easy compatibility between various C672x devices. 
http://www.ti.com/tool/sprc223 

Hi..

I have written a program on CCS 4.2 for the generation of a sine wave from PADK C6727. it seems the program is running and also being loaded successfully on the PADK, but I don't hear any output via a headphone. in fact, I have modified the existing program for analog loopback by including the sine wave generation in the interrupt service routine.

The sampling rate used for the sine wave has been set at 48 kHz. Is there anything we need to modify in the PADK for something which is generated internally?

Thanks,

Sajaad

In my opinion you have to create periodic interrupt from RTI. In your case sampling frequency is 48kHz, so it's Ts = 1/fs = 20,83us. In interrupt routine of RTI you have to clear interrupt flag of RTI and you can calculate sample of the sinusoidal wave. Sine wave is generally getting by:

u(t) = um*sin(2*pi*f*t + phase)

t = t + Ts. If Ts=period of your sine wave t=0. Then you have to calculate value for your DAC and send your sample to the DAC. Off course you can use dMax and sine table to do that. In this case interrupt routine should be make once per period.

I hope it's helpful and you can understand me.

Hi,

Thanks a lot for your help.

In fact, I have used the dMax and sine and modified the analog loopback program. Below is the section that I have modified while the other remaining part of the program, stays the same.

interrupt void nmi_isr( void )

{

    while(1);

}

interrupt void dmax_isr( void )

{

       unsigned PP;

    volatile unsigned *GPTransferEntry;

    static int *pDac = (int *)dmaxDacBuffer[0];

    //static int *pAdc = (int *)dmaxAdcBuffer[0];//

    //sinewave generation//

       #define SAMPLING_FREQ 48000

    #define PI 3.142

    float frequency = 1000.0;

    float amplitude = 10000.0;

    float theta_increment;

    float theta = 0.0;

    static int *psinout;

    float sinewave();

    {

       theta_increment = 2*PI* frequency/SAMPLING_FREQ ;

       theta += theta_increment;

       if (theta>2*PI) theta -=2*PI;

       *psinout = amplitude*sin(theta);

       return;

    }

         /*

       // Verify if a ADC transfer completed

       if( hDmaxAdc->regs->DTCR0 & (1<<ADC_TCC) )

       {

              hDmaxAdc->regs->DTCR0 = (1<<ADC_TCC);

              // Save the pointer of the audio buffer that has just been filled

              GPTransferEntry  = (unsigned *)&hDmaxAdc->regs->HiPriorityEventTable;

              GPTransferEntry += ((*(hDmaxAdc->hiTableEventEntryPtr)>>8)&0x07F);

           PP = GPTransferEntry[2] >> 31;      

              pAdc = (int *)dmaxAdcBuffer[!PP];

             }     

               */

              // Verify if a DAC transfer completed

                     if( hDmaxDac->regs->DTCR0 & (1<<DAC_TCC) )

                       {

                           hDmaxDac->regs->DTCR0 = (1<<DAC_TCC);

 // Save the pointer of the audio buffer that has just been transmitted

 GPTransferEntry  = (unsigned *)&hDmaxDac->regs->HiPriorityEventTable;

       GPTransferEntry += ((*(hDmaxDac->hiTableEventEntryPtr)>>8)&0x07F);

                         PP = GPTransferEntry[2] >> 31;      

                     pDac = (int *)dmaxDacBuffer[!PP];

               // Copy new samples in transmit buffer

              memcpy( pDac, psinout, FRAME_SIZE*NUM_CHANNEL*2*sizeof(int) );

               }

 }                   

when the program is build, it does not give any error but only one warning as follows:

"statement is unreachable" at line  " if( hDmaxDac->regs->DTCR0 & (1<<DAC_TCC) )".

when the program is loaded on the PADK, it appears fine but there is no output on a headphone.

Thanks,