DAC Playback Mux in Alsamixer

Hello Mikhail,

Which part are you using or are you trying to choose a DSP?

All of our SigmaDSPs can take in I2S signals. Some have built in DACs and others have to use I2S or TDM to go out to an external DAC. Let me know what part you are using and more details about your application.

Thanks,

Dave T

Hello Dave!

Thanks for answer. I try to capture I2S to DSP.

I have eval board and on it all work correct. I have problem on a Linux. I need start my adau1761 on the Linux board.

This is common description of my project. Just capture I2S sound, and play it sound to DAC. That is all.

1. If I play any stream on I2S (speaker-test, aplay ...), I can switch register "DAC play" to DSP out or I2S. I made simple scheme with sin tone. And when I switch "DAC play", I can listen or sin tone (from DSP) or music from I2S.

2. Correct I undarstand that doesn't matter "Serial Input route control" switch in the SigmaStudio for my case.

For capture I2S sound I should choose on the scheme in SigmaStudio "input1"- ch1&2.

Hello Mikhail,

I think I understand what you are asking. Excuse me if I am wrong.

This part is very flexible and has a lot of signal paths.

You can route the I2S serial port input to either go up to the DSP or you can route it to go directly to the DACs. This is done in register R58:Serial Input Route Control at address 0x40F2. (decimal 16,626)

Bits [3:0] are the SINRT[3:0] register bits.

Setting 0000 will send the output of the DSP to the DACs. This means that the serial port data will appear in the DSP using the cells in SigmaStudio and you can process the audio and route it to the DAC inside the DSP.

Setting any other setting 0001 to 1111 will two channels from the serial port and route it directly to the DAC. This means that the DSP DAC output will not work.

So this register selects the DAC input outside of the DSP. This is why if you select the serial input port you disconnect the DSP. The DSP can still route to other places, just not the DACs.

I do now know the Linux driver to know exactly what the defines are but with the serial port address and name you should be able to find it.

Thanks,

Dave T

Thanks a lot, Dave!

So, for process audio from I2S bus in the DSP and out to DAC, I should:

set R58 (0x40F2) = 0x00

and configure cells input in SigmaStudio?

same picture

http://prntscr.com/a4rf34

That config will work correct?

Hello Mikhail,

Yes, that is the signal flow in SigmaStudio that will route the first two channels of the serial port over to the DACs.

You must have the serial port registers set properly to accept the signal you are sending to it. Is it stereo(I2S), is it TDM, is there a BCLK delay, master or slave? All those settings will need to be looked at.

Thanks,

Dave T

Hello Mikhail,

I have one question regarding the part selection. Will you be using the ADAU1761 for the production units?

Dave T

Hello Dave!

Thanks for answer. I try to check Your idea.

I will use adau1761 for telephony application. I develop speakerphone with echo cancelation. This application will work under Linux. If do You have any questions, pls ask me.

Hello Mikhail,

I was concerned that you would look to use the automotive version, the 1461 later in production. That part will not be offered for very much longer so I would not want you to base a design on it. That was my concern.

So it looks like you are going out to an external DSP to do the echo cancellation? That is a good idea. It is difficult to do in the SigmaDSP.

Thanks,

Dave T

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