TAS3251: About the SRC function

Hi,

Not sure I got your point, please correct me if there is any misunderstanding...

So you used PPC3 to generate Biquad coefficients for different sampling rate, and you get different coefficients for different sampling rate, right? Please make sure that your generated coefficients matched with your sampling rate setting, because internal DSP algorithm need it to be so.

Thanks!

Regards,

Hao

Hi Zhang-san,

Thank you for quick reply.

>So you used PPC3 to generate Biquad coefficients for different sampling rate, and you get different coefficients for different sampling rate, right?

Yes.

The filter coefficient generated at Fs = 48 kHz in Case 1 is operating correctly in an input sampling rate environment of 48 kHz.
The filter coefficient generated at Fs = 96 kHz in Case 2 is operating correctly in an input sampling rate environment of 96 kHz.

TAS3251's datasheet

I think Process Flow 1 (96 kHz, 2.0 Standard Processing) does not have an upsampling SRC function.

please investigate.

Best Regards,
Hiroaki Masumoto

Hi Hiroaki-san,

Yes, I agree with you. If 96kHz sampling rate is selected, SRC could be internally bypassed as there is no need.

Regards,

Hao

Hi Zhang-san,

Thank you for reply.

As Process Flow 1 (96 kHz, 2.0 Standard Processing)

There is no SRC function.
If 96kHz input sampling rate is selected, the internal sampling rate is 96 kHz.
If 48kHz input sampling rate is selected, the internal sampling rate is 48 kHz.
If 32kHz input sampling rate is selected, the internal sampling rate is 32 kHz.

Is this my understanding correct?

Best Regards,
Hiroaki Masumoto

Hi Hiroaki-san,

SRC is working here to do the sampling rate conversion to 96k. Internal sampling rate is always 88.2 or 96kHz.

In process flow 1, the input sampling rate is 96k. It's the same as SRC output. So we say it's not functioning here.

Any question, feel free to ask us. Thanks!

Regards,

Hao

Hi Zhang-san,

The description of “8.5.2.2 Sample Rate Converter” in the TAS3251 data sheet is the same as your reply.

However, there are many errors in the TAS3251 data sheet.
There was no level meter function.

I evaluated it using TAS3251EVM and PPC3.

As a result of evaluation using the case 1 filter coefficient and the case 2 filter coefficient, if the 48 kHz input sampling rate is selected, the internal sampling rate is 48 kHz.

In the SLAA799A (TAS3251 process flows) document, Process Flow 1 does not have an SRC function.

Of course, there seems to be no SRC function to upsample the 48kHz input sampling rate to 96kHz.

TAS3251 datasheet [8.5.2.2 Sample Rate Converter]
The detected sample rate can be read at book 0x78 page 0x0C register 0x5C.
But register 0x5C to read the 48kHz input sample rate is not 0x00 00 00 02.
Register 0x5C to read the 48kHz input sample rate is 0x00 00 02 c0 or 0x00 00 02 c1 or 0x00 00 02 c2 or 0x00 00 02 c3 or 0x00 00 02 c4.

Please check again.

Best Regards,
Hiroaki Masumoto

Hi Masumoto,

If you want to read any register, you need to write "r 95 5c 04". Please check again.

Thanks!

Regards,

Hao

Hi Zhang-san,

Thank you for your reply.

I tried to run as you said.

The correct data was not read.

Since the PPC3 software is well done, the LSB of the I2C slave address is overwritten by interpreting the "R" and "W" commands.

The TAS3251 data sheet has many of the same descriptions as the TAS5780M data sheet.
The description of TAS3251 data sheet “8.5.2.2 Sample Rate Converter” is the same as the description of TAS5780M data sheet “9.5.2.2 Sample Rate Converter”.
I think the TAS3251 data sheet “8.5.2.2 Sample Rate Converter” needs to be corrected to the actual functional description of TAS3251.

Best Regards,
Hiroaki Masumoto

Hi Zhang-san,

Please let me know if you have any updates on these questions.

Regards,
Hiroaki Masumoto

Hi Hiroaki-san,

Sorry for the late reply... Please leave me a little bit more time to run test on EVM and do some internal information checking...

Thanks for the understanding.

Regards,

Hao

Hi Zhang-san,

Thank you for your response.

I am looking forward to hearing from you.

Regards,
Hiroaki Masumoto

Hi Zhang-san,

Please let me know if you have any updates on these questions.

Regards,
Hiroaki Masumoto

Hi Hiroaki,

Sorry for the late reply. I'm on a business travel, and will give the conclusion on Friday when I got back to office. 

Thanks for the understanding!

Regards,

Hao

Hi Zhang-san,

Thank you for your reply.
I understand your evaluation results.

Then I will contact you by e-mail.

Regards,
Hiroaki Masumoto