Making Things Talk

APPENDIX C 371

Simple Serial

Language: Arduino/Wiring

Listens for an incoming serial byte, adds one to the byte

and sends the result back out serially. Also blinks an LED

on pin 13 every half second.

int LEDPin = 13; // you can use any digital I/O pin you want

int inByte = 0; // variable to hold incoming serial data

long blinkTimer = 0; // keeps track of how long since the LED

// was last turned off

int blinkInterval = 1000; // a full second from on to off to on again

void setup() {

pinMode(LEDPin, OUTPUT); // set pin 13 to be an output

Serial.begin(9600); // configure the serial port for 9600 bps

// data rate.

}

void loop() {

// if there are any incoming serial bytes available to read:

if (Serial.available() > 0) {

// then read the first available byte:

inByte = Serial.read();

// and add one to it, then send the result out:

Serial.print(inByte+1, BYTE);

}

// Meanwhile, keep blinking the LED.

// after a quarter of a second, turn the LED on:

if (millis() - blinkTimer >= blinkInterval / 2) {

digitalWrite(LEDPin, HIGH); // turn the LED on pin 13 on

}

// after a half a second, turn the LED off and reset the timer:

if (millis() - blinkTimer >= blinkInterval) {

digitalWrite(LEDPin, LOW); // turn the LED off

blinkTimer = millis();