bare9, are we done yet?

examples/bare9.rs

+// now you are on your own.....
+//
+// look at the examples in the f4 crate
+// https://github.com/jsjolund/f4
+//
+// try out the examples/pwm-control.rs
+//
+// connect an oschillocope to the pwm output
+// check that you can control the pwm over the serial
+//
+//
+// your assingment is to improve the user interface
+// to take commands
+//
+// on          // turn on the pwm output
+// off         // turn off the pwm output
+// set p       // p being the duty cycle in %
+//
+// and optionally
+// freq f      // pww frequency te f hz
+// ...         // your own commands
+//
+// I would suggest using the bare8 as a starting point
+// and adding code from the pwm-control example
+// you may look if `parse` can be of use to you here...
+// make the command parser work first, and then add the pwm code.
+//
+//
+// commit your solution (bare9)
+//
+// https://play.rust-lang.org/,
+// offers a good way to prototype and share code snippets