Page 149 - Programming the Photon Getting Started With the Internet of Things

Here is the code to switch on the lightbulb:

int RELAY1 = D3;
int RELAY2 = D4;
int RELAY3 = D5;

int RELAY4 = D6;

void setup()
{
//Initialize the relay control pins as output

pinMode(RELAY1, OUTPUT);
pinMode(RELAY2, OUTPUT);
pinMode(RELAY3, OUTPUT);

pinMode(RELAY4, OUTPUT);
// Initialize all relays to an OFF state
digitalWrite(RELAY1, LOW);
digitalWrite(RELAY2, LOW);
digitalWrite(RELAY3, LOW);

digitalWrite(RELAY4, LOW);

//register the Spark function

Spark.function("relay", relayControl);
}

void loop()
{

// This loops forever
}

// command format r1,HIGH
int relayControl(String command)
{
int relayState = 0;
// parse the relay number

int relayNumber = command.charAt(1) - '0';
// do a sanity check
if (relayNumber < 1 || relayNumber > 4) return -1;

// find out the state of the relay
if (command.substring(3,7) == "HIGH") relayState = 1;
else if (command.substring(3,6) == "LOW") relayState = 0;

else return -1;