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TAS5756M - HybridFlow 4 Configuration

Reinhard F.
Prodigy 80 points
Other Parts Discussed in Thread: TAS5756M

Hi everybody!

Thanks to the information in this forum and the PurePath Console application I have been able to get my custom hardware running quite flawlessly. However, being in the final stage of my project I encountered a problem that I haven’t been able to resolve over the past few weeks. Simply put, the configuration of the HybridFlow 4 program just doesn’t work.

I followed all the instructions provided in the “HybridFlow Processor User’s Guide (SLAU577, January 2015)” to export the register settings from the PurePath Console and I also added the required writes to exit the shutdown mode to the generated file. The initial configuration of the amplifier with the exported settings works as expected, but changes to the HybridFlow parameters have no effect on the output signal.

So although I write the same values to the amplifiers on my custom hardware as the PurePath Console does to the amplifiers on the EVM, I don’t get the same results/behavior.

First, I suspected my application on the host processor to be the cause of this problem, but after some research I found the following thread: https://e2e.ti.com/support/amplifiers/audio_amplifiers/f/6/p/432825/1550254#1550254

The reported problem is exactly the same that I am experiencing, but unfortunately there is no solution provided.

As there is little to no documentation on the HybridFlow registers I really don’t know what to try next. Therefore, I would be thankful for any help you can provide.

Regards,

Reinhard F.

  • 0
    TI__Guru 52115 points
    Hi Reinhard,

    How did you get the initial configuration file? If you can upload the xml file for the PPC2, I will take a look for you.

    What are the changes to the HybridFlow parameters you were mentioning? EQ settings?

    Andy
  • 0 in reply to Andy Liu (BMS)
    Prodigy 80 points

    Hi Andy,

    Thank you very much for the quick response.

    I am using the default HF4 configuration of the mono amplifier on the EVM to initialize my amplifiers. (When I have selected the HF4 program I click the "run" button (green arrow) to start it on the EVM. In order to export the configuration I simply use the "Register dump" function in the "Direct I²C Read/Write" tab. I assume this is the correct procedure?) You can find the xml file attached below, but as I mentioned it just includes the default configuration of HF4.
    MyTAS5754_6MNHF_HF4.xml

    The parameters I want to change are primarily the coefficients of the biquad filters (e.g. filter type, fc, gain,..), I haven't tried to change EQ settings yet. A quick example: When I set the first biquad to low pass (Butterworth 1) with a cutoff frequency of 500Hz, the I²C logging window shows the following output:

    w 9a 00 2e
    w 9a 6c 04 0e b6 00 02 07 5b 00 00 00 00 00 3b f1 4a 00 00 00 00 00
    w 9a 00 2c
    w 9a 01 05
    w 9a 00 2e
    w 9a 6c 04 0e b6 00 02 07 5b 00 00 00 00 00 3b f1 4a 00 00 00 00 00
    w 9a 00 00

    These filter settings have an audible impact on the output of the EVM, but when I set the same values on my custom board, nothing changes.Could this be due to I²C timing issues when writing to the TAS5756M? Or is more likely to be a configuration error?

  • 0 in reply to Reinhard F.
    TI__Guru 52115 points

    Hi Reinhard,

    If you would like to change the biquad coefficients on the fly, you do need to know some tricks. Let me comment more after the lunch break.

    Andy

  • 0 in reply to Andy Liu (BMS)
    TI__Guru 52115 points

    Hi Reinhard,

    The slides below show another way to dump a configuration file.  Usually you will get a smaller dump file.

    2806.How to Dump a Config File.ppt

    Andy

  • 0 in reply to Andy Liu (BMS)
    TI__Guru 52115 points

    Hi Reinhard,

    I guess I know what the root cause of your issue is. Take a look at the slides below:

    Biquad Coeff.pptx

    Andy

  • 0 in reply to Andy Liu (BMS)
    Prodigy 80 points
    Hi Andy,

    Thank you very much for your efforts. I will try your suggested solution as soon as possible.

    Reinhard
  • 0 in reply to Andy Liu (BMS)
    Prodigy 80 points
    Hi Andy,

    Your guess was right, I can now set the biquad coefficients during operation without any issues.
    Thank you very much for all your assistance.

    Have a great day!

    Reinhard