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Fez Cerb 40 II - Suggestions for Real Time audio application


#1

Hi everyone,

I am planning on writing a real time audio application on a Fez Cerb 40 II.
Based on some simple tests, writing it all in .net will not be possible due to performance.

The basic idea is that I would have an audio ‘rendering’ loop which write data from a circular buffer to a DAC (high performance) and c# code which writes to the buffer asynchronously (lower speed)

So I was looking at ways to this. Looking through the docs, it seems I could:

  • extend the NETMF
  • use RLPLite

Does anyone have any experience in either technique?
I’m guessing ‘RLPLite’ would be the better option?

Any tips, suggestions, advice would be very appreciated!
Thanks
Guy


#2

No experience so I can’t help on that front.

RLPlite “helps” if you still need the microframework to provide other parts of the system - like the file handling, other less time critical IO requirements, etc. That’s where commercial systems engineering cost and time can be saved.

To extend the netmf you can start with the community port of netmf4.3 and go from there. But whether that actually gives you any benefit I guess really depends on hardware and how fast you need to feed data to your output device and how fast you can read it.

(I hate saying this :slight_smile: ) The third option is to go back to C and write for the processor using the tools ST give you (or other vendor ARM compilers/libraries). Cerb40 is a great hardware platform if it meets your pincount needs and there’s no reason you have to leave netmf in place if it isn’t giving you what you need.


#3

Hi Brett,
Thanks for you feedback.
My project just need one fast method, and the rest are all slow operation, so I think RLP is the way to go.


#4

@ gwpt, you could use an MP3 decoding chip and send the audio to it. https://www.sparkfun.com/products/11684


#5

I had thought of that but I am actually generating the wave data on the fly.
Hence it’s RAW PCM data not compressed audio, so I just need to move it to the DAC at the correct speed.

I don’t think that board would help me in that case…
Cheers
Guy


#6

I got this exact board from SparkFun on my desk as we speak… We are working on realtime audio stuff. We’ll inform on our progress with it as we continue to develop…


#7

Ooo. Would love to hear of your progress! Thanks :slight_smile:


#8

@ gwpt - seems to work pretty good so far

Audio clip from Resources

And MP3 from SD card

Sound quality is actually pretty good ;D - still needs more work tough…