Other Parts Discussed in Thread: TLV320AIC3106
Hi,
I'm trying to generate and play a simple sinusodial wave of some frequency Fc, by using the Logic PD Zoom Development board with the C6748 SOM. My configuration is as follow:
- C6748 DSP
- TLV320AIC3106 Audio CODEC
- CCS 5.1.1 with DSP/BIOS v5.41.11.38, Code generation tools v7.3.2
- EDMA3 LLD v1.11.03.01
- PSP drivers v1.30.01 for the C6748
My program is basically a modification of the Audio example that came with the PSP drivers: instead of simply replaying the signal on line-in to line-out, I want to generate a sinusodial wave (tone) and rather play this. I generate a sine wave as follow:
- Allocate a buffer to hold generated sine wave samples:
temp_buf = (Short *)MEM_calloc(DDR_HEAP, BUF_LEN * sizeof(Short) , BUF_ALIGN);
temp_buf is of type Short and is allocated in the same way as the SIO buffers for the Audio interface driver.
- I generate the sine wave samples:
rad = 2*PI*(fc/48000.0);
for(j = 0; j < BUF_LEN; j++) {
temp_buf[j] = (Short)(sinf(rad * j)*32767) ;
}
The configured sample rate of the CODEC is 48kHz and the samples are scaled to fit into a Short.
- I attempt to continuously play the samples through the CODEC using this code:
// Reclaim empty buffer from the output stream to be reused
SIO_reclaim(audio_out_stream, (Ptr *)&xmt, NULL);
memcpy(xmt, (Ptr)&temp_buf[0], BUF_LEN * sizeof(Short) );
// Issue full buffer to the output stream
SIO_issue(audio_out_stream, xmt, BUF_LEN * sizeof(Short) * TX_NUM_SERIALIZER, NULL);
Upon measuring the resulting output signal on an oscilloscope I found that the signal was heavily distorted, not nearly the clean sine wave I was expecting. The configurations of the AIC3106, I2C, McASP and EDMA are the same as in the Audio example of the PSP drivers. I suspect the problem is probably misconfiguration, but exactly wat is incorrectly configured, I cannot seem to figure out.
Is it perhaps necessary to configure the EDMA in a more specific manner? Can someone please provide me with some insight into the problem? Please take into account that I'm inexperienced with the operation of CODECs.
Thanks in advance!
Reinier
