Tone causes crash with frequency = 0

[ghost]

It's not uncommon to use tone with frequency = 0 to indicate 'silence/no note'.
Example: https://github.com/arduino/Arduino/blob/master/build/shared/examples/02.Digital/toneMelody/toneMelody.ino
This crashes right now, I expect because of a division in zero in: https://github.com/esp8266/Arduino/blob/master/cores/esp8266/Tone.cpp

timer1_write((clockCyclesPerMicrosecond() * 500000) / frequency);
Admittedly the behavior on Arduino for frequency = 0 doesn't seem to be documented, and I expect on some other cores it would also crash or do weird things..

[Razpudding]

I second this issue. I worked around it by checking if frequency is '0' and if so setting it to '1'. If someone has an actual solution I'd love to hear it.

[pfeerick]

Over on the Oak we've also just experienced this issue as well, as it is essentially based on the ESP8266 core. In the issue I opened over there (digistump/OakCore#75) to document that it's a known problem,

Upon having a quick look through the original Arduino implementation, it appears it should suffer from the same issue, as it would also divide by zero. However, it appears that "the AVR doesn't have a divide instruction, so can't itself know that a divide-by-zero has occurred", and basically fakes divides with shifts, thus doesn't actually realise something is very, very wrong!?

I proposed the following solution to work around the issue, but only at the user sketch level... it doesn't really fix the problem as it results from the implementation, but it at least prevents the sketch from crashing...

Basically, Instead of

tone(3, melody[thisNote], noteDuration);

to use

if (melody[thisNote] == 0)
{
  noTone(3);
  delay(noteDuration);
}
else
{
  tone(3, melody[thisNote], noteDuration);
}

[devyte]

Code is already merged, closing.