While debugging our new SerialUSB implementation I needed to use the regular Serial2 interface to track down ASSERT failures, but couldn’t find a spare FTDI chip around the lab. I’ve got one of these super slick little ones in the mail, but in the meanwhile I wrote this sketch in about 2 seconds which turns a spare Maple into a Serial-USB passthrough:

void setup() {
  Serial2.begin(9600);
}

void loop() {
  if(SerialUSB.available()) {
    Serial2.write(SerialUSB.read());
  }
  if(Serial2.available()) {
    SerialUSB.write(Serial2.read());
  }
}

There are a million better ways to do this but I love how easy this was!