Hi,

>> - Use complementary PWM on the two pins and low pass filter (or use
>> PWM so high that the result is inaudible).
>
> Switching a PWM for an inaudible signals equal creating EMI and noise
> on the board for nothing while some power is used for this.

    I do not thing this would be so bad ! The piezo element I am using is 
not a big one and even considering the capacitive nature of it the current 
is quite small. I always use a pair of resistors at the CPU pins that will 
work as a low pass filter when combined with the piezo capacitance.. The 
piezo is also mounted directly on the PCB making the "loop" small.

    It will take me a few weeks before I implement it but I will get back to 
the list with the results..

Best regards,
Alexandre Guimaraes

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