I have just tested my code on Arduino UNO (supply of 5v) as opposed to Arduino fio 328 (supply of 3.3v)
and it works like a charm, no garbage characters
I figured the serial out from the ph stamp is at a different level somehow to the arduino fio..
any help to get it to work with the fio
I have already tried the HEF4050 with both 3.3 and 5v as supply but still same garbage coming out...
I am experiencing exactly the same problem as you (the garbage characters), same Arduino Fio 328p. Haven't tried on a 5v model yet(unfortunately I made a Fio specific PCB).
Have you eventually found a workaround?