Featured Articles
Announcing Pi
Technical Specifications
Raspberry Pi FAQs
Win a Pi
Raspberry Pi Wishlist
Actions
Forum Thread Details
  • State Suggested Answer
  • Replies 8 replies
  • Answers 2 answers
  • Subscribers 677 subscribers
  • Views 1511 views
  • Users 0 members are here
Related

Real Time DSP using the Cirrus Logic Card

Former Member

I am looking at the Cirrus Logic card to act as the interface to do some audio DSP functions on a sample-by-sample basis in real time for SDR (Software Defined Radio).   Is this appropriate for the device?  It would have to run in a tight loop (preferably > 96 kHz):

   sample audio inputs --> process sample on the RPi in C language --> output on audio out  --> loop back.

I have not been able to find any user libraries for dealing with the card.  I would want it to loop as fast as possible.

 

I have the code working on a Arduino Due, but the 12-bit converters are marginal.

 

Thanks,

Derek

Parents
  • 0

    Hi everybody,

    Thanks for taking the time to reply to me.   Unfortunately I have had to decide that the Cirrus board and RPi is not the way to go for me for a couple of reasons:

    1) Linux is a terrible OS for time critical operations because of the time-outs it takes from applications - as an old Unix guy I should have remembered that,.

    2) With all the difficulties with the drivers, and the fact that the Cirrus DSP code is inaccessible and cannot (easily) be created/modified, it's just not worth the effort.

     

    What I've decided to do is use a dedicated DSP board using the Analog Devices ADAU1701 DSP chip.   It's just what I need with 24 bit ADC and DACs at 192 kHz, and what's more it has a graphical programming interface using Analog Devices Sigma Studio system.   You program it by dragging, dropping and connecting DSP blocks, and compiling and loading with one button press.   Wow - it took me about 15 minutes to develop and debug one of my demodulators using Hilbert transforms, Chebyshev high and low pass filters, summers, etc.   Didn't have to write one line of code, simply change parameters on the blocks.

     

    Analog Devices makes an evaluation board (expensive), Elektor makes a DIY kit for a nice little unit ($88) - with all components but you have to built it, freeDSP has developed a system and makes the PCB specs and Gerber files available for free so that you build your own.  This chip is the basis for the miniDSP audio processing system.

     

    I am going to buy the Elektor system.   Check it out at

    https://www.elektor.com/adau1701-universal-audio-dsp-board-130232-71

    There is a video there that shows how to program it using Sigma Studio... Fantastic!

     

    Derek

Reply
  • 0

    Hi everybody,

    Thanks for taking the time to reply to me.   Unfortunately I have had to decide that the Cirrus board and RPi is not the way to go for me for a couple of reasons:

    1) Linux is a terrible OS for time critical operations because of the time-outs it takes from applications - as an old Unix guy I should have remembered that,.

    2) With all the difficulties with the drivers, and the fact that the Cirrus DSP code is inaccessible and cannot (easily) be created/modified, it's just not worth the effort.

     

    What I've decided to do is use a dedicated DSP board using the Analog Devices ADAU1701 DSP chip.   It's just what I need with 24 bit ADC and DACs at 192 kHz, and what's more it has a graphical programming interface using Analog Devices Sigma Studio system.   You program it by dragging, dropping and connecting DSP blocks, and compiling and loading with one button press.   Wow - it took me about 15 minutes to develop and debug one of my demodulators using Hilbert transforms, Chebyshev high and low pass filters, summers, etc.   Didn't have to write one line of code, simply change parameters on the blocks.

     

    Analog Devices makes an evaluation board (expensive), Elektor makes a DIY kit for a nice little unit ($88) - with all components but you have to built it, freeDSP has developed a system and makes the PCB specs and Gerber files available for free so that you build your own.  This chip is the basis for the miniDSP audio processing system.

     

    I am going to buy the Elektor system.   Check it out at

    https://www.elektor.com/adau1701-universal-audio-dsp-board-130232-71

    There is a video there that shows how to program it using Sigma Studio... Fantastic!

     

    Derek

Children
No Data