int incomingByte = 0;   // for incoming serial data

void setup() {
  Serial.begin(9600);//Arduino to Computer over USB
  Serial1.begin(9600);//BB to Ardunio UART
}

void loop() {

        // send data only when you receive data:
        if (Serial.available() > 0) {
                // read the incoming byte:
                incomingByte = Serial.read();

                // say what you got:
                Serial.print("I sent: ");
                Serial.println(incomingByte, DEC);
                Serial1.print(incomingByte);
        }
}