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I wanted to generate an echo using the DSP TMS320F28335.

Chetan Nehete
Prodigy 20 points
Other Parts Discussed in Thread: TMS320F28335

How can i do so. Deos anyone have the code for the echo generation??

  • 0
    Guru 192875 points
    Hi Chetan,

    Can you brief us more on what kind of echo generation are you talking about? Audio processing for echo generation?

    Regards,
    Gautam
  • 0 in reply to Gautam Iyer
    Prodigy 20 points
    yes audio processing. I am using TMS320F28335 and generating an audio echo. basically a delayed audio signal repeating again and again.
  • 0 in reply to Chetan Nehete
    Guru 192875 points
    There's no documentation or example files as such on audio processing. But do check this thread and try contacting
    e2e.ti.com/.../371869

    Regards,
    Gautam
  • 0 in reply to Gautam Iyer
    Prodigy 100 points
    First off, the F28335 has a "largeish" enough pool of ram to create your echo. You will most likely want to interface with some sort of external RAM chip to give yourself a deeper reverb sound.

    The principle can be very simple to extremely complicated. The simplest method is implement a circular buffer that stores the t-N sample with dampening. Every sample you take from your A/D is mixed with buffer[N]*A, where N can be a number dependant upon a combination of your sampling rate and the depth of your reverb and a dampening coefficient. Then store the currentSample + buffer[t-N]*A back in to buffer[t] and continue on.

    Here is a link to where I hosted on github: github.com/.../guitarEffects

    You'll want to go to GuitarEffects/src/effect.c and look at processReverb(). I used some sort of IIR filter design for this that I can't remember for the life of me, but the effect was "ok", by far my least favorite of this project. My only complaint was at the depth of the reverb I created. If I had more time on this project, I would have used an external RAM chip.

    Feel free to use the reset of the effect processing I have listed there. The wah came out really nice.