Generate Sine Wave with C6748 LCDK

Hi,

I'm using TMS320C6748 LCDK with xds100 v2 emulator to do some applications by using the book "Digital Signal Processing and Applications with the OMAP-L138 eXperimenter".

From the forum I know that "The textbook is compatible not only with the LogicPD OMAP-L138 eXperimenter but also with both the OMAP-L138 LCDK and the C6748 LCDK.". 

I try to generate sine wave by using the code in Chapter 1, which is as follows

// L138_sine48_buf_intr.c //

#include "L138_aic3106_init.h"

#define LOOPLENGTH 48

#define BUFLENGTH 256

int16_t sine_table[LOOPLENGTH] =   {0, 1305, 2588, 3827, 5000, 6088, 7071, 7934,    8660, 9239, 9659, 9914, 10000, 9914, 9659, 9239,    8660, 7934, 7071, 6088, 5000, 3827, 2588, 1305,    0, -1305, -2588, -3827, -5000, -6088, -7071, -7934,    -8660, -9239, -9659, -9914, -10000, -9914, -9659, -9239,    -8660, -7934, -7071, -6088, -5000, -3827, -2588, -1305};

int16_t sine_ptr = 0; // pointer into lookup table

int32_t buffer[BUFLENGTH];

int16_t buf_ptr = 0;

interrupt void interrupt4(void) // interrupt service routine {

  int16_t sample;

  sample = sine_table[sine_ptr];       // read sample from table

  output_left_sample(sample);          // output sample

  sine_ptr = (sine_ptr+1)%LOOPLENGTH;  // increment table index

  buffer[buf_ptr] = (int32_t)(sample); // store sample in buffer

  buf_ptr = (buf_ptr+1)%BUFLENGTH;     // increment buffer index  

  return;

}

int main(void) {  

 L138_initialise_intr(FS_48000_HZ,ADC_GAIN_0DB,DAC_ATTEN_0DB);

  while(1);

}

After I debugged the project, it says that

C674X_0: Output:  Target Connected.

C674X_0: Output:  Memory Map Cleared.

C674X_0: Output:  Memory Map Setup Complete.

C674X_0: Output:  PSC Enable Complete.

C674X_0: Output:  PLL0 init done for Core:300MHz, EMIFA:25MHz C674X_0: Output:  DDR initialization is in progress....

C674X_0: Output:  PLL1 init done for DDR:150MHz C

674X_0: Output:  Using DDR2 settings

C674X_0: Output:  DDR2 init for 150 MHz is done

C674X_0: Output:  DSP Wake Complete.

So I think that the configuration is correct.

When I run the c-code, the values in "sine_table"(16 bit signed integer) are correct, however, the values in the "buffer"(32 bit signed integer) which are for the output are wrong, i.e., the waveform is not sine.

In addition, I can't hear any sound from the output of the C6748 LCDK by earphoe.

Is it associated with the DIP switch or other settings, since I can generate and see the sine wave by C code only in simulation with CCS5, i.e., without using anything related to the C6748 LDCK?

Thanks.

Best regards,

PP