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Embedded and Microcontrollers
Embedded Forum Audio PIC 'n' mix
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  • 8_bit
  • audio
  • microchip
  • microcontrollers
  • sampling
  • pic
Related

Audio PIC 'n' mix

samplerman
samplerman over 14 years ago

I have recently being using a PIC18F46K20-E/PPIC18F46K20-E/P to play back audio samples from an external EEPROM using the SPI module

to retrieve the data etc and play audio via the internal PWM module. Here's the question, I need to play back up to four samples

simultaneously ( polyphonic), which is the best technique for polyphonic playback? maybe alternate samples fed to the PWM

in order so that the ear integrates the samples, or maybe 'mixing' the sample data in the digital domain and feeding the summed

data to the PWM? any thoughts?

 

Carl

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  • JohnDSiviter
    JohnDSiviter over 14 years ago

    You should try phoning Farnell Technical.

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  • Jorge_Garcia
    Jorge_Garcia over 14 years ago

    Hi Samplerman,

     

    Sound like many natural systems follows the principal of superposition. My recommendation is to mix(sum) the four inputs and then feed the summed signal to the PWM, that will be the easiest solution, believe me if you have a good ear you'll be able to distinguish the seperate frequencies.

     

    An easy experiment is run a normal 50%DC square wave to a speaker system. Not only do you hear the fundamental but you can also hear the much higher(little annoying) third harmonic and possibly the fifth harmonic. The other harmonics have much lower power content relative to the fundamental so they get "washed out" by our ears.

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  • samplerman
    samplerman over 14 years ago in reply to Jorge_Garcia

    Thanks for your recommendations Jorge.

    I will give try mixing the audio in the digital domain first, then feeding the result into the PWM for output

    to the amplifier.

    regards

    Samplerman

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