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Recording the best headset audio in a portable form factor

lion mclionheadlion mclionhead 12/08/2017 at 00:080 Comments

The STM32 found itself driving headphones by ganged PWM outputs. Ganged because it allowed more current. This worked much better than the DAC while consuming a lot more power. It was acceptable. Because the PWM updated at 40khz, there was a lot of aliasing. It required a 3rd order FIR filter which knocked out all the high frequencies. It sounded horrible but better than aliasing & could be done for each sample. Also, be sure to tie your unused opamp inputs to the power rails.





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