Getting Started with Arduino

Serial Communication

You learned at the beginning of this book that Arduino has a USB connection that is used by the IDE to upload code into the processor. The good news is that this connection can also be used by the sketches that we write in Arduino to send data back to the computer or to receive commands from it. For this purpose, we are going to use a serial object (an object is a collection of capabilities that are bundled together for the convenience of people writing sketches).

This object contains all the code that we need to send and receive data. We're now going to use the last circuit we built with the photoresistor and send the values that are read back to the computer. Type this code into a new sketch (you can also download the code from www.makezine.com/getstartedarduino):

Example 5-5. Send to the computer the values read from analogue input 0 Make sure you click on "Serial Monitor" after you upload

#define SENSOR 0 // select the input pin for the
                 // sensor resistor

int val = 0; // variable to store the value coming
             // from the sensor

void setup() {

 Serial.begin(9600); // open the serial port to send
                     // data back to the computer at
                     // 9600 bits per second
}

void loop() {

  val = analogRead(SENSOR); // read the value from
                            // the sensor

  Serial.println(val); // print the value to
                       // the serial port

  delay(100); // wait 100ms between
              // each send
}

After you've uploaded the code to your Arduino, press the "Serial Monitor" button on the Arduino IDE (the rightmost button in the ...