Is it possible for an Arduino to produce a sine wave to a piezoelectric buzzer?
Some piezo buzzers only need a DC input. What are the specs of your piezo buzzer?
You could use an R-2R ladder DAC arrangement, connected to some of the uC's IO lines. Then use a look-up table in the uC to drive a sine wave out the DAC. You may need to buffer that DAC output with an opamp to drive the buzzer, depending on the current required.
I don't have one yet. When it says (?? hz), does that mean what it's capable of, and not what it actually produces?
Can you post a datasheet that you are looking at?
I'm guessing that you put a DC voltage across it, and it produces a tone of that specified frequency (probably with some harmonics too...).
A little late but are you you looking for something like this?
Arduino tone example
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