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mixing two I2s streams and a Lin/mic input - PCM3070?

Calum Mackinnon
Genius 4155 points
Other Parts Discussed in Thread: PCM3070, TLV320AIC3268, TLV320AIC3263, TLV320AIC3262

Hey

I am designing a system that has a 5x2 I2S switching chip. I want to be able to take the audio signal (I2S) from BOTH outputs of the switch, bring them into an Audio Codec, mix them with another analog signal (line/mic level) and then output the new I2S data.

I was looking at the PCM3070 -

There is a primary and secondary I2S interface. The primary interface has dedicated pins for clocking(BCLK and WCLK), Dout and Din.

The secondary interface uses pins MFP3 and MFP4 for serial data in and out respectively. Obviously I will lose the primary function of those pins(SPI bus)

Table 2-2 in the PCM3070 reference guide shows the register settings to set the pins correctly

However if you look at fig 2.43 the Din and S_DIN are muxed before they go into the “Audio Digital Serial Interface” – I assume this is the “Data interface” in fig 1.1 – i.e. only one stream at a time? I don’t see how you can control this mux, even if we can control that mux I'm not sure how we can take two serial I2S streams at the same time.

If I can't use this device to take two I2S streams in simultaneous is theer another option?

Cheers

Calum

 

  • 0
    TI__Expert 3110 points

    Hi Calum,

    The PCM3070 cannot do what you are trying to achieve. I would recommend looking into the TLV320AIC3263, TLV320AIC3262, or the TLV320AIC3268. All of those should be able to mix two I2S signals with a lin input. Those devices can be programmed using the GUI, PurePath Studio.

    Regards,
    Mike Ulrich

  • 0 in reply to Mike Ulrich
    Prodigy 155 points

    Hello Mike,

    I have taken your advice and went ahead with the TLV320AIC3268. I feel very confident with my current schematic as I used the reference design on your site to create it. But I do not feel as confident in the I2S portion.

    There are three I2S Ports. I need on I2S running to the TLV320AIC3268. After mixing with analog signals, I need two I2S lines to leave the TLV320AIC3268. There are like ten different ways to wire this, and I'm sure only one of them is the correct way.

    Do I use Port ASI1 for I2S input, and then use the DOUT as an output as well? Then for my second I2S output I could use Port ASI2?

    Or do I ignore DOUT on ASI1 and use ASI2 as I2S out 2 and ASI3 as I2S out 3?

    I could not find any reference schematics that do this and would love for you to send me one or at least tell me in the correct direction to go. I have attached my schematic below for reference.

    Thank you!

    Regards,

    Max Makhnyk

    DSP TLV320AIC.pdf

  • 0 in reply to Max Makhnyk
    TI__Expert 3110 points
    Hi Max,

    You can use Din1 and Dout1 for one of your I2S signals and mix it with the analog signal in the miniDSP. The second I2S signal can be sent in through Din2 and come out through Dout2.

    The alternative (if your systems supports TDM) is to send a TDM signal into Din1 and mix the signal in the miniDSP and send it back out through Dout1 as a TDM signal.

    Hope this helps!

    Regards,
    Mike Ulrich
  • 0 in reply to Mike Ulrich
    Prodigy 155 points
    Hello Mike,

    Thank you for your response; although it did clear up the situation a little, I am not sure it answers my question in fullness. The I2S input part I understand, I only have one I2S input so its going into Din1.

    But the I2S output I'm still lost on. I need two I2S outputs, both being identical. Can I make Dout1 and Dout2 function at the same time, with the same exact signal? Or can I just use Dout2 and have two different connections come out of Dout2 and go to two separate sources?

    Thank you!

    Regards,
    Max Makhnyk
  • 0 in reply to Max Makhnyk
    TI__Expert 3110 points
    Hi Max,

    My apologies for misunderstanding what you were trying to do. You can indeed send 1 I2S in through Din1 and send back 2 identical signals through Dout1 and Dout2. You can program the miniDSP to route the outputs to both Dout1 and Dout2 and you will see identical outputs at the 2 pins.

    Regards,
    Mike Ulrich