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TLV320AIC3262: ASI1 and ASI2 routing issue with multi channel

sebastien castel
Prodigy 110 points
Part Number: TLV320AIC3262

Hello everyone,

i'm using the EVM AIC3262 to interface the codec to I2S (TLV3262 is slave): 

- on ASI1 : DSP 16 bit 4 channels

- on ASI2 : DSP 16 bit 2 channels

Both ASI are running at he same Fs 16Khz

I want to route analog audio to the 4 channels of ASI1 and 2 channels of ASI2 thanks to this PPS : 

In this example, when i set Scale_1 to "0", the audio to ASI1 and ASI2 is muted, regardless of the coefficient of Scale_4.

The following PPS with 2 channels on ASI1 and ASI2 works normally.

Do you have any idea ?

Thank you for your help.

Sebastien

  • TI__Mastermind 23305 points

    Hi Sebastien,

    Does ASI 1 and 2 work in the first case if Scale_1 is set to 1? I'm also noticing your second PPS replacing the multiple output block with the I2S block. If you keep the second PPS, but use a two channel Multi_Channel_Digi output block instead (using same I2C settings), does it still work?

    Thank you,
    Jeff McPherson

  • in reply to Jeff McPherson
    Prodigy 110 points

    Hi Jeff,

    here is the behaviour ;

    i will try to use 2CH Multi_Channel instead of standard I2S block tomorrow morning.

    Actually i shared a simplified PPS, my real problem is with the following PPS with a similar issue :

    Even if I2S_OUT2 is not connected (red cross), i have audio from other source to ASI2 thanks to the third channel of ASI1 (in green).

    Despite this, the rest works fine : 

    • Multi_In to Multi_Out : OK
    • MonoDec to Multi_Out : OK
    • I2S_IN2 to Multi_Out : OK
    • MonoDec to I2S_OUT2 : OK but cannot be muted with MIX_G1_LINEIN
    • Multi_in to MonoInt8xOut : OK

    Thank you for your help

  • in reply to sebastien castel
    Prodigy 110 points

    it seems the same PPS works with ASI3 instead of ASI2 and ASI1 multichannel.

    For the moment, i do not need to use the 3 x ASI so i'm ok with this configuration but i would appreciate if you have any explanations.

    As in the future, i will have to use 8 channels, i'm wondering if ASI3 will suffer the same issue of ASI2 and 4 channels.

    Thank you

    Sebastien

  • in reply to sebastien castel
    TI__Mastermind 23305 points

    Hi Sebastien,

    To clarify, all you did was change the I2S_IN/OUT blocks to I2S_IN3/OUT3? Did any digital audio settings change from your original picture?

    Thanks,
    Jeff McPherson

  • in reply to Jeff McPherson
    Prodigy 110 points

    Hi Jeff,

    Jeff McPherson said:
    all you did was change the I2S_IN/OUT blocks to I2S_IN3/OUT3?

    i replace blocks from I2S_IN2/OUT2 to I2S_IN3/OUT3.

    I kept ASI1 with Multi_Channel_Digital_In_1 and Multi_Channel_Digital_Out_1

    Jeff McPherson said:
    Did any digital audio settings change from your original picture?

    No exactly the same settings and PPS (except ASI2 to ASI3)

    Sebastien

  • in reply to sebastien castel
    TI__Mastermind 23305 points

    Hi Sebastien,

    I'll need to check internally. Our PPS support is limited as this is a legacy product and is not in any active development.

    Another clarifying question, does the audio still appear on DOUT2/ASI2 after you switched to the ASI3 blocks?

    Thank you,
    Jeff McPherson

  • in reply to Jeff McPherson
    Prodigy 110 points

    yes there is audio on DOUT2 even if my PPS has ASI1 and ASI3

  • in reply to sebastien castel
    TI__Mastermind 23305 points

    Hi Sebastien,

    I discussed with one of our DSP experts and we found that the multi_digital_out block is sharing resources with the I2S_2 block.

    In short, the DSP has 4 stereo "ports" to interface the I2S data to the output pins. The multi channel block interfaces with all of these ports while the I2S_x blocks interface to only one of these stereo ports. When you use both the multi channel block and the I2S_2 block, they are both accessing port 2 which is why data is appearing on ASI2 from channels 3 and 4 of the multi channel block as you highlighted. Using I2S_3 ensures that each port is only connected to one output. 

    What you've encountered is just a limitation of how the DSP was designed as well as being limited to 8 channels (4 ports). When you try to go to 8 channels, I2S_2 and 3 will be sharing ports with the 8 channel block, so ASI2 and 3 will have copies of channels 3&4 or 5&6 respectively. It was assumed that a full TDM bus would not need the other I2S headers since all 8 channels would be present on one data line already.

  • in reply to Jeff McPherson
    Prodigy 110 points

    Hi Jeff,

    it's quite an important limitation you described here. Again, for now, as i'm using only 4 channels so I can work around this problem.

    Jeff McPherson said:
    so ASI2 and 3 will have copies of channels 3&4 or 5&6 respectively

    Does it mean that i can use these interfaces without issue :

    ASI1 with channels 1,2,3,4 & 7,8 and ASI3

    ASI1 with channels 1,2 & 5,6,7,8 and ASI2

    Do you know if this architecture is similar in the other codec with TDM (3268 ?)

    Thank you for your feedback

    Sebastien

  • in reply to sebastien castel
    TI__Mastermind 23305 points

    Hi Sebastien,

    You're understanding is correct.

    The DSP structure is the same in the other codecs like the 3268.

    Best regards,
    Jeff McPherson