Making Things Talk

WIRELESS COMMUNICATION 203

#define sensorPin 0 // input sensor

#define txLed 2 // LED to indicate outgoing data

#define rxLed 3 // LED to indicate incoming data

#define analogLed 9 // LED that changes brightness with incoming value

#define threshold 10 // how much change you need to see on

// the sensor before sending

int lastSensorReading = 0; // previous state of the switch

int inByte= -1; // incoming byte from serial RX

char inString[6]; // string for incoming serial data

int stringPos = 0; // string index counter

First, give the I/O pins

names and set up

some variables for tracking the change

in the switch:

void setup() {

// configure serial communications:

Serial.begin(9600);

// configure output pins:

pinMode(txLed, OUTPUT);

pinMode(rxLed, OUTPUT);

pinMode (analogLed, OUTPUT);

// set XBee's destination address:

setDestination();

// blink the TX LED indicating that the main program's about to start:

blink(3);

}

Next, in the setup() method,

configure serial transmission, set the

modes on the I/O pins, and configure

the XBee’s destination address:

8

void setDestination() {

// put the radio in command mode:

Serial.print("+++");

// wait for the radio to respond with "OK\r"

char thisByte = 0;

while (thisByte != '\r') {

if (Serial.available() > 0) {

thisByte = Serial.read();

}