Part Number: PCM9211
I have a question regarding I2S audio routing within a design around PCM9211.The PCM is used as multiplexer here.There is one output device (an I2S input class D amp) on the PCM's main output.There are two input devices: one on the AUXIN0 port, another on the AUXIN1 port.
The output device is a I2S receiver in clock slave mode.The input devices are I2S transmitters in clock master mode.From the PCM9211's datasheet I understand this setup is ideal, right?
Now, the second source device, has also an I2S data input which I want to use. There are however no seperate clock lines for this input, the same as for it's output must be used.My goal is to make a route possible for audio comming from source 1 to the source 2 device input.
Since the PCM has multiple outputs (AUXOUT), which can be independent from the main output, I was thinking to use the PCM MUX for this as well.However: I read in it's datasheet AUXOUT can only operate in I2S clock master mode.Problem: The source 2 device is already master...
Is there something I missed out and is there a way to use AUXOUT or another output to accomplish this audio route?If no: what is the best alternative?
The PCM9211 is tremendously versatile, so I believe it's possible in some way, but I'm not sure.
So, just to be clear:
This (see diagram attached below), would be possible if the AUXOUT port could be an I2S clock slave.But, that's not possible, I THINK...
In reply to Julien Roels:
As you mention, AUXOUT port can be used only as a clock Master, so the configuration you are mentioning cannot be implemented.
-Diego Meléndez López Audio Applications Engineer
In reply to Diego Melendez:
Thank you for confirming.What possible alternative do you recommend? I was thinking about the following options:
1) Using an SPDIF output from the PCM (MPO0 or MPO1), and connecting this to a DIR which converts to I2S and is able to operate as I2S clock slave at the same time.However... I think such a device doesn't exist? (I only know DIR IC's which are clock master untill now).
2) Using some buffer device to split (duplicate) the DOUT-line from source 1 and feeding one output to the PCM and one output to source 2 (bypassing the PCM altogether).
3) Tweaking source 2 to act as an I2S clock slave, and let be the AUXOUT port the clock master of both source 2 and AUXIN1. However, I don't know if such input-output loopback of clocklines is allowed for PCM9211.
Because I think (1) is impossible, and (3) is too hard because I don't know how I can tweak source 2; I think option (2) is my best shot.So, for option (2): do you have a recommendation on which buffer device I should use to split the DOUT-line?Or is there a better alternative which I didn't think of?
Thanks in advance!Kind regards
EDIT 1: I just realized option (2) is also impossible because of both sources are I2S clock masters.Seems like my only options are (1) and (3)...I will investigate if option (3) is possible. Otherwise, do you have an idea for a DIR which can be I2S clock slave for (1)?
EDIT 2: I just figured out tweaking of source 2 is impossible. Leaving only option (1).
Another possible option is to tweak source 1 and let this be a clock slave, dictated by the clock lines of source 2.I think this might be possible (altough this will include many implications for this block).With this option (4) I will need the same device as I would need for (2): a buffer for the I2S dataline with two outputs to drive the PCM input and source 2 input from one output.
Thanks in advance,Kind regards
Probably the best option is to configure either Source 1 or 2 as I²S slave device an setup the other one as the master for the whole subsystem:
For the buffer, we have several options in TI portfolio, we used in the past a CDCLVC1102 device for a similar application. You might also ask in Clock and Timing forum for a more specialized recommendation.
I think that might work well. Adding the SRC between the sources will allow you to send the data from Source 1 to Source 2 being both devices a master for their bus.
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