SRC4190 TDM mode

Hi, Prachi,

I've asked my colleague to look at this issue with you.

-d2

Hi,Prachi ,

I am sorry for my late.

I hope you don't mind I reply to you late today.

Thanks,

Flora Wang

Hi,Prachi,

SRC4190 TDM bus application is serial.Just as the picture shows:

If one of the slave device can't get the data form the previous device,this device can't talk to the next device,too.

if my answer doesn't answer your question,please let me know.

Thanks ,

Flora Wang

Hi Flora,

Thank you for your reply.

I understand from the above that in the TDM chain, if one of the devices does not get the TDM data input, then the data cannot reach the next device. 

Suppose if the TDM chain is fine, and one of the devices does not get serial data input. What would happen in that case?

Regards,

Prachi 

Hi,Prachi,

I am sorry,what do you mean what would happen? you mean whether the device has some signal to report it hasn't data input?

Thanks,

Flora Wang

Hi Flora,

What I mean is, if input to one of the devices is lost, does it affect the TDM data? Is the TDM data correct except for the  sub-frame corresponding to that one device? 

Does the data from other slave devices remain proper?

Regards,

Prachi  

Hi,Prachi,

SRC4190 can use the I2S input or the TDM input.For TMD input please kindly see datasheet page21,figure 12. if the there is no data on TDM input,there will be no data on the SDOUT. The next device can't have proper data.

if you use I2S input,the same thing will happen when there is no data input.

Does my understanding correct(about your question)?

Thanks,

Flora Wang

Dear Flora,

I think I will try to explain my question more clearly.

If the serial audio input to one device in TDM chain is lost, then  

1) does the device insert any garbage data in the TDM frame?

2) or the device does not add any data in the TDM frame, and passess the data as it is that it receives at the TDMI pin to its SDOUT pin?

3) or there is no TDM output from this device?

Please let me know how the TDM chain is affected in that case?

Regards,

Prachi

Hi,Prachi,

Let's see the TDM fomat.

The TDM in the audio is actually PCM in time division.

PCM don't have any CRC or report error,it's one way ,just pass the data.

So if the data is lose,I mean the input data is zero or no input, TDM is output,it can't do anything for the data.

Thanks,

Flora Wang

Dear Flora,

 Thank you very much for your quick reply.

I have explained our use case in more detail. I hope this clears any misunderstanding.

Our use case is as shown in the below figure.

When all three audio sources present, the processor will receive the 6 mono channel TDM data from the SDOUT pin of Slave #1.  

Please confirm.

Now, if suppose, the audio input to Slave #2 is not present.  Both the I2S input data and the clock is not present for Slave #2. The input to the Slaves #1 and #3 are still present.

 In that case we believe that processor still receives data in 6 channel TDM mode. The slots corresponding to Slave #2 will not contain any data. 

Please confirm

Regards,

Prachi

Hi,Prachi,

Thanks for your patience. I am sorry for my misunderstanding.

Now I understand your concern.

1.You are right, the processor will receive the 6 mono channel TDM data from the SDOUT pin of Slave #1.  

2.if the CLK(BCKO,LRCKO) of slave 2 is not present,there I think the processor can't have the data of slave1 and slave2. Because the TDM can't work without CLK.

3.if the CLK is right,but just lose the data of slave 2,the processor will have slave 1 and slave 3 data. Slave 3 can find the their own slot by countig the clk,so we must make sure the clk is right.Then it will be no impact to the next sub frame.

Thanks,

Flora Wang

Dear Flora,

Thanks a lot. This has answered my question.

I have another query.

The READY output signal of the device is given to the MUTE input pin. In this case when the input is not present, would the output be all zeroes?

Regards,

Prachi

Hi,Prachi,

I think if there is no I2S input(data and CLK),the device can't detect LRCKI and can't determine input-to-output sampling frequency ratio.The RDY pin may can't be active low. if it connected to Mute,it will send the mute signal.

You can verify it on your board.

Thanks,

Flora Wang