se si tratta solo di prendere in input dati da tastiera allora la cosa diventa cosi'
if (Serial.available() > 0) {
int inByte = Serial.read();
// do something different depending on the character received.
// The switch statement expects single number values for each case;
// in this exmaple, though, you're using single quotes to tell
// the controller to get the ASCII value for the character. For
// example 'a' = 97, 'b' = 98, and so forth:
switch (inByte) {
case 'a':
//code for a
break;
case 'b':
//code for b
break;
case 'c':
//code for c
break;
case 'd':
//code for d
break;
case 'e':
//code for e
break;
default:
// se nessuna opzione è tra quelle prestabilite
//code
}
}