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PCM5142: Custom interpolator: RAM based hybrid flow

Borge Strand-Bergesen
Intellectual 685 points
Part Number: PCM5142
Other Parts Discussed in Thread: PCM5242

Hi, 

I'm about to start experimenting with custom filters on the PCM5142. 

The datasheet says:

"8.3.4.2 Interpolation Filter The PCM514x provides 4 types of interpolation filters, selectable by writing to Page 0, Register 43, D(4:0). Additional RAM based Hybrid Flows can be implemented by selecting Program 31, and downloading instructions and coefficients to the device."

But PurePath (2.1 for PCM5242) does not have settings for custom FIR filters. 

Please let me know how to start exploring custom interpolation filters. 

In my application I have custom C code that accesses the PCM5142 over I2C. It is straightforward to write the contents of a data structure to the DAC. But it will be a bit more tricky to have PurePath connected live to the DAC. 

Best regards, 

Børge

  • 0
    TI__Mastermind 19320 points

    Hello, I have to  consult with my team and see who is the best person to  pass this ticket to ,may be I need to transfer the ticket to another group.

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    Intellectual 685 points

    Thank you Arash, 

    I'm eager to start pouring my Matlab code into my PCM5142 board. If necessary via .h files. I have a lot of legacy FPGA filter code for interpolation. It will be very interesting to see how much of it will fly in the PCM5142. 

    By the way, is PurePath 2.1 the right version for PCM5142 (and possibly PCM5242)?

    Best regards, 

    Børge 

  • 0 in reply to Borge Strand-Bergesen
    TI__Mastermind 19320 points

    I have passed along  your question to the team who can answer this. I  will let you know about what they say.

    PurePath 2.1 would work for PCM5x42 as well.

    Arash.

  • 0 in reply to Borge Strand-Bergesen
    TI__Mastermind 19320 points

    Hello Borge, I want to inform you that we generally don’t support custom interpolation filters or for that matter any custom PPS component development. A custom interpolation filter would need an update of both coefficient and instructions. Customers do not have the tools to build a custom component. It was supported when we used to distribute the PPS IDE. But we have stopped doing that for  many years now.

    If it is a business case, let me know about it and I can do more follow ups with the team as a new miniDSP program will have to be written to match with the custom interpolator coefficients.

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    Intellectual 685 points

    Hi Arash, 

    I certainly have a business case for this. How can we switch to a private channel to discuss it? My email address is borge@henryaudio.com

    I'm excited to use the PCM5142 and PCM5242 for various products. They will partially be use to update a design that used PCM1704 with custom interpolation in an FPGA. That DAC used my own Laplace-to-Z conversion transform to achieve finite-duration FIR filtering. This is something I'm eager to port to the newer processing models and DACs

    I am familiar with quite a few obscure low-level programming methods (Motorola 56k assembly just to name one) and won't bog down your support channel if you were to give me access to tools and documentation. 

    Best regards, 

    Børge

  • 0 in reply to Borge Strand-Bergesen
    TI__Mastermind 19320 points

    Thanks Borge. I will close the post here and continue via email.

    Regards,

    Arash

  • 0
    Intellectual 685 points

    Hi Arash, 

    Could you please get back to me on email? If you have already sent me an email, please let me know. 

    I would like to present three specific business cases that will benefit greatly from us having insight into PCM5142 programming. 

    We have purchasing decisions that are right around the corner, with dwindling stock at distributors.

    Best regards, 

    Børge

  • 0 in reply to Borge Strand-Bergesen
    Intellectual 685 points

    Hi Arash, 

    Could you please get back to me on email? If you have already sent me an email, please let me know. 

    I would like to present three specific business cases that will benefit greatly from us having insight into PCM5142 programming. 

    We have purchasing decisions that are right around the corner, with dwindling stock at distributors.

    Best regards, 

    Børge

  • +1 in reply to Borge Strand-Bergesen
    TI__Mastermind 19320 points

    Hi Borge, please check your email.

    Thanks.

    Arash