CCS/TMS320C5515: writing data of codec audio to sd card whitout lost samples.

The sampling frequency is 8000Hz. 
Look at  the other MMCSD projects but many of them do not allow me to read data later on a computer because I do not generate a file.
That's why I chose this project (csl_mmcsd_atafs_ext_example) although I'm not sure if it's the right one.
my code first read aic3204 and after write to file:

for(n=0;n<30;n++)
{

    for(index = 0; index < CSL_MMCSD_ATA_BUF_SIZE; index++)
     {
       aic3204_codec_read(&left_input, &right_input); //read aic3204
       mono_input = stereo_to_mono(left_input, right_input);
       gMmcWriteBuf[index] =mono_input+32768;

      }

/* Write data to the file */
ATA_seek (pAtaFile, n*CSL_MMCSD_ATA_BUF_SIZE);
ata_error = ATA_write(pAtaFile, gMmcWriteBuf, CSL_MMCSD_ATA_BUF_SIZE);//write file block data

printf("FIN\n");
ATA_close(pAtaFile);

The result of acquiring a 1000Hz sinusoidal signal is:

The signal has discontinuities and this is the problem.While writing in file lost samples.(yellow).The loss of samples is every 256 samples, the size of the buffer.
Looking at the forum people comment that it would be convenient to use the DMA ping pong mode to avoid losing samples, but I am lost in the DMA configuration and implements in my code.
I need help or suggestion of how to acquire data without losing samples while writing to file.
Thanks.