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Altera_Forum's avatar
Altera_Forum
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15 years ago

NIOSII for Sound Recording

Hi,

I am an amateur to NIOSII and have very thin knowledge with this features.

Hereby wish to have yours advise how can i start to develop a sound recording and play back system with NIOSII.

I wish to develop an embedded system that use for sound data analysis with Altera DE2. Microphone is attached to Mic port and the RS-232 is connected to laptop.

Other than that, i also wish to ask is it a better choice of using NIOSII rather than Verilog HDL for same purpose? Would it be hard to write the FFT code with Verilog HDL as i know that NIOSII work with C programming.

Do i need license to implement the NIOSII design on my board?

I do appreciate with more reference or link is provided for me to start the design work.

Many thanks!

11 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    You can use the web edition to develop a Nios II system and just tether it over JTAG when you download to the board. If you were going to ship what you are working on then yes you would need to get a Nios II license.

    FFT is a fairly computational algorithm so you might find writing that in C will work for the line rate you need. If I was implementing this I would probably use Nios II for the control plane and use dedicated hardware for the FFT and DMAs to move data around. Here is an example MP3 player that you can take a look at:

    http://www.alterawiki.com/wiki/mp3_player
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    Thank you for your reply.

    So if i m not going to ship my work (I am just work it for academic purpose, my lab project) , i don't need a license to work the NIOS II on my board? I can straightly do the design on my board with NIOSII? The board i have with me is belongs to my university lab.

    Thank you for your reference. I have refereed it and it is a cyclone III. May i know any other reference that work the same application on cyclone II DE2?

    Please advise again!

    Many thanks. :)
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    Other than that, may i know what do you mean by dedicated hardware for FFT? I was planning to work out the FFT function on a single board (The altera DE2).

    Other than that, I noticed altera is DSP builder. May i know how can i intergrate the DSP builder's FFT in the C code? Actually i have done with my simulation and my FFT algorithm with MATLAB. Now is going to wok out the thing on FPGA with the purpose to make the system independent from PC processor.

    Please advise how can i work out the thing. Thanks again
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    Sorry my knowledge is very limited for the DE2 board so I'm not sure what you should do. Since this is part of a lab project you don't need a license (if your school is using Altera devices they may have the license though). If not basically the way it works is that most Altera IP is free to use for academic and experimental usage, and under such a license you just have to have the JTAG connection present if you want to use the design in actual hardware for demonstration purposes.

    As for the FFT algorithm my only experience is implementing it in C code on TI parts and using C code with C2H:

    http://www.altera.com/literature/tt/tt_nios2_c2h_accelerating_tutorial.pdf

    http://www.altera.com/literature/tt/c2h_tutorial.zip

    it's a pretty standard algorithm so you'll probably find many implementations of it in hardware as well as altera providing it as a megafunction that you parametrize as well.

  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    Also somewhere else in this forum someone was asking about implementing the FFT algorithm in software on Nios II or in dedicated hardware, if you search for it you'll probably find it. I barely remember DSP from school but to me FFT means 2 multiplies and 2 additional/subtractions per input pair using the basic radix 2 algorithm. So per input there is a lot of software calculations going on which is why most people use DSPs and/or dedicated hardware for this sort of thing.

    If I was implementing FFT under high bandwidth requirements I would use an FFT with Avalon streaming inputs and outputs and use DMAs that can transfer between memory-mapped and streaming to shovel data in and out of the dedicated FFT hardware. This might be overkill for what you need to implement so consider this the extreme end of the spectrum between all C code and highly parallelized hardware :)
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    Thank you for your reference and replies.

    So says that if i am going to capture sound from mic then store the sampled sound data to memory, which part of the memory (Flash/SDRAM/SRAM) tat i should use?

    And is it correct if i fetch the data from the memory then proceed for FFT using C programming? I have gone through the reference link. may i know where can i get the C code in the example so that i can have a practice b4 i seek for advise again?

    It would be great for other reference that shows the way to record sound using NIOSII on DE2..

    Many thanks!
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    Sorry... i just noticed the .zip file from u.. So i will try to run the example 1st... Hopefully can get myself more understand with the flow of NIOSII.

    Anyway... i still hope to have your advise how can i deal with the audio recording as mentioned.

    Thanks again!
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    I would skip the mp3 part of the software since it's probably highly optimized but the general organization of the system should give you an idea of what to do. In a nutshell for what you are doing I think something like this will work:

    ADC --> DMA --> RAM --> DMA --> FFT (and other streaming stuff...) --> DMA --> RAM --> whatever you are going to do with the data

    This might be overkill but this is how I would keep Nios II out of the data movement path and use it just to control everything.
  • Altera_Forum's avatar
    Altera_Forum
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    15 years ago

    I have tried a simple NIOSII example. Can i know where i can get the C program that used for sound recording? Since NIOSII operates with C program, is it possible to implement the ordinary sound recording source code?

    DMA is it a temporary buffer that store the data? But how can i implement the DMA? My Altera DE2 has only SDRAM, SRAM, Flash Memory.

    Actually where can i get relevant reference? As i wish to study more 1st and experiment more b4 i get advise again. Currently i m still blur how to implement sound recording with NIOSII.

    Thank you.