This may be answered elsewhere or may not be possible which is why I can't find a quick answer but can the Arduino Uno handle multiple digital outputs at the same time? I'm designing a polysynth with multiple speakers and only one pin can handle the output at one time using the tone command. I want to be able to have multiple speakers operating at different frequencies but I can't find a command that will allow me to vary multiple outputs at the same time. Is this even possible with the Uno?
Yes using direct port manipulation
However I doubt it is the answer to your problem, which is a little vague at the moment.
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