Multi ADAU1467 Configuration

Andrew.Choi Question

May 18, 2020 00:00

HI ADI's

One of my customers wants to configure using Sigma DSP(ADAU1467) as below.

N DSPs are controlled by one MCU, and each DSP is connected to an 8-channel ADC and DAC.

Each DSPs operate independently, but I want to operate by exchanging data (audio data) between them.

I think it would be possible to I/F each DSPs with I2S. Is this possible?

How many DSPs can be connected if possible?

If the above concept is not possible, how should it be designed?

Thank you

Audio Signal Processors

adau1467

SigmaDSP Audio Processors

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DaveThib Reply

May 21, 2020 00:00

Hello Andrew,

There is a limitation for the I2C address. There are only four different addresses possible so you cannot have more than four DSPs on the same I2C bus. The way around this is to either setup multiple I2C busses and have the MCU switch between the busses as needed. Another way is to use SPI so you can use multiple slave selects.

When you say they are operating independently, will they be on the same master clock?

If they are not on the same clock then you will have to use sample rate converters for the signals going between the processors but it can be done.

So how many processors? Well, you will get into issues with length of clock lines and long power runs. I have seen one person who designed four of the ADAU1452 into one product. As far as I know it went well. Going above four will start being difficult is my first thought but certainly can be done with some careful design.

Dave T

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Andrew.Choi Reply

May 21, 2020 00:00

Thank you for your answer Dave T.

I understand the I2C channel limits.

I'll check how the clock is designed.
However, since DSP is planned to be manufactured on each board, it is highly likely to be separated.

Is audio routing okay?

1) The DSPs all operate independently.

2) ADC / DAC is connected to each DSP by I2S. (8ch)

3) Is it possible to connect each DSP to I2S?

4) Can you recommend a connection other than I2S?

Thank you

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DaveThib Reply

May 22, 2020 00:00

Hello Andrew,

Andrew.Choi said:
1) The DSPs all operate independently.

Then if they are not on the same master clock then you will have to use sample rate converters for the communications between each DSP. The DSP is limited to 16 channels of sample rate conversion. So you could do 8 in and 8 out.

Andrew.Choi said:
2) ADC / DAC is connected to each DSP by I2S. (8ch)

If you use TDM8 then you can reduce the number of serial ports required.

Andrew.Choi said:
3) Is it possible to connect each DSP to I2S?

Yes, but I think TDM4 or TDM8 would be better as long as the distance between the DSPs is not too great and the sample rates are not high.

Andrew.Choi said:
4) Can you recommend a connection other than I2S?

If you end up having to go a long way then perhaps you can use the SPDIF inputs and outputs but you would be limited to 2 channels in and out. doing this will gain the ability to transmit these signals much further.