Shield扩展板

#include <SoftwareSerial.h>
SoftwareSerial mySerial(7, 8);

void setup() {
  Serial.begin(9600);
  Serial.println("Goodnight moon!");

  // set the data rate for the SoftwareSerial port
  mySerial.begin(9600);
  mySerial.println("Hello, world?");
}

void loop() {
  // run over and over
  if (mySerial.available())
    Serial.write(mySerial.read());
  if (Serial.available())
    mySerial.write(Serial.read());
}