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PCM5121: How to consider coefficient and command script

na na78
Guru 16770 points

Part Number: PCM5121
Other Parts Discussed in Thread: SRC4392

Hi

We have following questions.

1.

According to datasheet of PCM5121, for example, Master volume control is described with coefficient in Table 27 page 40.

However, we could not understand the meaning of each coefficient, such as Volume_ZeroX_1_volcmd, volout, volout_loudness and so on.

In addition, regarding to coefficient of Volume_ZeroX_1, only VolumeCoefficient could be changed in Pure Path Studio.

(I could not get part of Volume_ZeroX_1_volcmd, volout, volout_loudness...)

So, I'm wondering if it is necessary for user to understand the all coefficient and its function.

Should we understand the specification of coefficient?

Or is it OK for user only to manage processing block in pure path studio?

2.

I found example script from EVM user guide.

I extract following for example.

---

# The following script is used for playback via USB

# RESET RESET THIS IS MASTER RESET FOR SRC (48kHz)

# Page 0 = DEFAULT for Control

# Write to page 0

w E0 7F 00

...

---

What is "E0" represented?  

I believe slave address should be either 0x98, 0x9A, 0x9C or 0x9E.

BestRegards

  • 0
    TI__Guru 56763 points
    Hello,

    We do not expect the user to know the meaning of the coefficients, as some are internal variables of the DSP. You should use the coefficients generated by PurePath Studio in your design.

    The default scripts list a few commands for the SRC4392 to configure the input of the EVM. These can be deleted in your application.

    Thanks!
    Paul
  • 0 in reply to Paul_Frost
    Guru 16770 points
    Hi Paul

    Thank you for your reply.

    I opened PCM5121 ROM file and change coefficient but I could not execute "Generate code" from PPS GUI.
    "Gerenrate Code" could not be selectable.

    How to generate script file after changing coefficient?

    We don't have EVM so we did not connect EVM to PC USB.

    BestRegards
  • 0 in reply to na na78
    TI__Guru 56763 points
    Hello,

    This has been shown to me recently and I am looking for a solution as this seems like a bug or oversight. If you like you can send me the pfw files and I can generate the .cfg file with the coefficients.

    Thanks!
    Paul
  • 0 in reply to Paul_Frost
    Guru 16770 points
    Hi Paul

    Thank you for your support.
    I will ask you to generate configuration file if that is required, thanks.

    As mentioned before, regarding to Volume_ZeroX_1, parameters being changed are only "Volume" and "VolumeCoefficient" in property area.

    What is page number and register number for Volume (VolumeCoefficient)?
    We can see Volume_ZeroX_1_DataBlock and Volume_ZeroX_1_CoeffBlock from datasheet. Which one?

    And I have additional question.
    How to change dynamically these coefficients while device in operation? Is it possible?

    BestRegards
  • 0 in reply to na na78
    TI__Guru 56763 points
    Hi na na,

    I think I have answered this in the other posts. But essentially the coefficients configure the volume modifier in the DSP only, so you could set you fullscale value in the preset ROM flow. The registers 60-64 in page 0 are the volume controls that can be modified during operation.

    Thanks!
    Paul