Ok this is all still very confusing to me.
Two things I think I got it:
First I need to convert the ASCII char to hexadecimal.
Second I am still confused as to read 2 values on the serial.read.
So: "1200, 30" will NOT result in freq = 1200 and duration = 30
How do I do that?
I wish Arduino Software would have a better interface using Serial Monitor. Something like a ASCII to hex converter. I mean my programming skills are based on trial and error ( much of it) and interaction with the serial comm is the best way to test things.
Anyway, I read the article on the blog, but as expected i became very confused.
The point is I want to test tones at diferent frequencies and durations using serial interface. Anyone knows a good solution?