Modified version of the relay program

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Here’s my crack at a modified version of the program provided for the relay shield. I changed it a bit to allow a variable amount of relays. Also I added the ability to toggle the relays:

int RELAYS[] = {D0, D1, D2, D3};
const int num_relays = (sizeof(RELAYS) / sizeof(byte));

// This will hold the relay states
int states[num_relays];

void setup()
{
    for (int i = 0; i < num_relays; ++i)
    {
        //Initilize the relay control pins as output
        pinMode(RELAYS[i], OUTPUT);
        
        // Initialize all relays to an OFF state
        digitalWrite(RELAYS[i], LOW);
        
        states[i] = 0;
    }

   //register the Spark function
   Spark.function("relay", relayControl);
}

void loop()
{

}

// command format r1,on
int relayControl(String command)
{
  // parse the relay number
  int relayNumber = command.charAt(1) - '1';
  
  // do a sanity check
  if (relayNumber < 0 || relayNumber > (num_relays - 1)) return -1;
  
  int state = states[relayNumber];

  // find out the state of the relay
  if (command.substring(3,5) == "on") state = 1;
  else if (command.substring(3,6) == "off") state = 0;
  else if (command.substring(3,9) == "toggle") state = !state;
  else return -1;
  
  // Store the value so we can keep track of state
  states[relayNumber] = state;

  // write to the appropriate relay
  digitalWrite(RELAYS[relayNumber], state);
  return 1;
}
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2

Cool! Looking forward to trying this out here. :smile: