TLV320AIC DAC output rate control

Jack Morrison

Other Parts Discussed in Thread: TMS320C6416T

I am building a waveform generator using a DSK6416 board (TMS320C6416T DSP and TLV320AUX23B codec). I would like to be able to vary the output frequency by just changing the rate at which the DSP sends samples (over McBSP) to the codec. I have the codec fixed at 96KHz.

This doesn't seem to work right - the output looks ugly on a scope. The codec datasheet doesn't have any details on how the DAC behaves in this usage - e.g. the codec is expecting two samples (left and right) every 10.4 usec. If I give it pairs of samples at longer intervals, does it not just hold the last provided value and update the output as soon as a new value is provided?

over 15 years ago

0 J- over 15 years ago

TI__Mastermind 46195 points

EDIT: Wrong Codec

0 Converter Apps over 15 years ago

TI__Mastermind 28585 points

Jack,

I am not sure I understand your question. There is no buffer for the data to the DAC. The DAC is expecting real time data at the sample rate.

Best Regards.

0 Jack Morrison over 15 years ago in reply to Converter Apps

Prodigy 140 points

Thanks for the responses.

Converter Apps said:

The DAC is expecting real time data at the sample rate.

Yes, the question is what happens if it gets data at a lower rate - does the analog output hold at the previous sample value, and change to the new value as soon as the new sample is provided?

Actually the main problem I was having was not changing the DSP's output rate (by setting the DSP timer period via DSP/BIOS functions) correctly. Basically the output looks okay now, although I'd still like to confirm the DAC's behavior.

Audio

Audio forum

TLV320AIC DAC output rate control