tone support no greater than 500Hz pitch

[lzq420241]

ArduinoCore-mbed/cores/arduino/Tone.cpp

Line 27 in b0a3c08

ticker.attach(mbed::callback(this, &Tone::toggle), 500ms / frequency );

[lzq420241]

better change 500ms to 500000us to support a higher pitch

[facchinm]

Hi @lzq420241 ,
thanks for reporting, I thought std::chrono to be a bit smarter and apply the right operation (I was wrong 🙂 ).
Will fix in a minute!