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Audio Synthesizer

Question asked by shallcross.harris on Oct 16, 2013
Hey guys,

I've recently been designing a synthesizer based on the STM32F4 Discovery board. I'm using a PT8211 DAC for the audio output and an interrupt triggered at 48KHz. My audio is generated using a DDS method and my wavetables are 4096 entries long. Theoretically, this should give me a minimum frequency without interpolation of 48k/4096 = 11.72Hz which is far below the lowest frequency I'm wanting to reproduce.

I'd like to stress here that currently, the synthesizer works and has multiple audio effects etc. What I am wondering though is how would I go about oversampling my audio? I'm not too sure on how this is done and would appreciate any help that anybody can give! I'm currently using 16bit SPI with a baud rate divider of 2 for maximum speed. My DAC supports up to 18.4MHz bitclock and 384KHz word clock, theoretically allowing for up to 8x oversampling.