Very often (not always!) the screen gets completely dark whenever the first sound rings.
Digging into source code I found, that both (PWM and Tone) are both using timer1. This smells a lot like a concurrency problem.
Can anyone confirm that one must not use PWM and Tone at the same time?
Are there any recommendations to work around that problem? Currently I just analogWrite(PIN, 0) to stop timer1 before any sounds. Ugly, but works.
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Tom