dears! thank you for supporting! I have done this problem, 83.3Hz I have 8,3 cycles per buffer 100ms, or, 12.04ms per period of wave. And then, the 0.3 of 8.3 cycles is the problem, I need a complete number for use on buffer, not a decimal number ... 0.3 is not a complete wave, its a 30% of a cycle. For fix this, I used just 8 cycles por buffer, keeping the period of wave 83.3 (12.04ms), for this, my new buffer time is 96.38ms! Resume: for others int frequency, like 60, 80, 90, 100hz, I can use 100ms for buffer. But, for decimals frequency, like 83.3, I need to use 96.38ms or (int Cycle/period = 8/12.04 = 96,38). For now, its work very good =D