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TAS3108 fast enough?

Thomas Deuble
Intellectual 550 points

Other Parts Discussed in Thread: TAS3108

Hi everybody.
I´m working on the TAS3108 now. So I did this process flow with the pure path studio www.detoma.com/test/TAS3108pf1.zip
How can I determine if the TAS3108 is fast enough so that this process flow is working?

Thanks for any reply.

  • 0
    Intellectual 455 points

    Thomas, the TAS3108 can process about 2800 instructions per audio sample at 48kHz. Each instruction is 54 bits long and your flow compiled into a code section of 12451 bytes with the version I had on my computer at the time (not the latest version). This would seem to fit. Did you try it?

    Neil Quarmby
    www.milton-electronics.com

  • 0
    TI__Genius 14545 points

    Thomas Deuble said:
    How can I determine if the TAS3108 is fast enough so that this process flow is working?

     

    Thomas,

        Neil is correct, the device can process 2812 cycles/ Sample. A simple peak into the assembled DSP source code revealed your flow takes 1815 cycles (Running on PurePath Studio Version 1.88 Build 3 (With Patch 1 Installed). You've got plenty of room from a cycle count point of view.

    Drew

  • 0 in reply to dabuan
    Intellectual 550 points

    Thanks for your answeres Neil and Drew.

    But how did you calculate this?

    When I compile the TAS3108pf1 process flow I get a 60.185 Byte hex file on my computer.

    Tom

     

  • 0 in reply to Thomas Deuble
    TI__Genius 14545 points

    Thomas Deuble said:
    But how did you calculate this?

     

    The number of instructions are simply calculated by the dividing the DSP Clock Frequency by the Audio Sampling Period. This allows one to determine how many cycles are available at the given frequency per sample.

    135,000,000 Cycles(Instructions)   *         1 second                  =  2812.5 Cycles / Sample                                

                   1 second                                48,000 Audio Samples        

       You can exchange the sample rate for the frequency of your application to determine the number of cycles you have. This example assumes Fsample = 48kHz 

     

    The 1815 number came from looking at the open source DSP assembly code output file that gets generated in MyProcessFlows folder available under the following directory

    C:\Program Files\Texas Instruments Inc\Purepath Studio\My Process Flows\<TAS3108pf1>

             

  • 0 in reply to dabuan
    Intellectual 550 points

    Thank you Drew,

    I did buy a TAS3204EVM (need AD and DA as well) and tested the process flow - it works.

    But when a flat frequency response is required and I set the Biquads to AllPass then I get either no output or a horrible noise. What´s wrong?

    And could you please provide the equations for the Biquad filters because I need to do a GUI for the project as well and need to calculate B0,B1,B2,A1 and A2 for the various filter types from f0, gain and Q. Thanks.

    Actually are there any schematics from the TAS3204EVM because I will need to make some alterations in order to fit my project.

    Thanks for your answer.

    Thomas

  • 0 in reply to Thomas Deuble
    Intellectual 455 points

    Thomas, here are the schematics for the 3204 EVM.

    I am surprised that you are having problems with the biquad filters, your description suggests that they are not being initialised properly. Can you post your process flow so that I can take a look or email it direct to me if you prefer.

    Neil Quarmby

    www.milton-electronics.com

  • 0 in reply to Neil A Quarmby
    Intellectual 550 points

    Thanks for the schematics Neil.

    Please find the process flow attached.

    The filters only behave funny if they are set to Allpass.

    Do you actually know the equations from f0, gain and Q to B0,B1,B2,A0 and A1 for the various filter types?

    Thanks.

    Thomas

  • 0 in reply to Thomas Deuble
    TI__Genius 14545 points

    Thomas, Neil,

        I've moved the post to the following thread as this issue is unrelated to the current Subject Line of 'TAS3108 fast enough?" Please move discussions  /  questions to the below thread to reduce confusion.

    http://e2e.ti.com/support/applications/audio/f/22/t/52334.aspx