code 1

/*
Core1.
*/


int sendLedPin = D7; //choose the pin for the send (local) LED
int inputPin = D4; //choose the input pin (for a pushbutton)
int receiveLedPin = D0; //choose the pin for the receive (Core2-dependent LED)
int val = 0; //variable for reading the pushbutton pin status
int sendLedVal = 0; //variable for keeping the state of the local pushbutton dependent LED (D2)
void ledTwoToggle(const char *toggle, const char *onOff); //handler function for Spark.subscribe()

void setup() {
    pinMode(receiveLedPin, OUTPUT); //Set the pin controlling the Core2-dependent LED as an OUTPUT
    pinMode(sendLedPin, OUTPUT); //Set the pin controlling the local pushbutton-dependent LED as an OUTPUT
    pinMode(inputPin, INPUT); //Set the pin connected to the pushbutton as an INPUT
    digitalWrite(sendLedPin, LOW); //Ensure the local LED is set to off to begin with
    digitalWrite(receiveLedPin, HIGH); //Ensure the local LED is set to off to begin with
    Spark.publish("Core1Toggle", "State", 0, PRIVATE); //Set up Spark.publish() so that the state of the local LED is published to the Spark Cloud PRIVATELY
    Spark.subscribe("Core2Toggle", ledTwoToggle, MY_DEVICES); //Set up Spark.subscribe() so that the state of Core1's Led is recorded and handled by ledTwoToggle
}

void loop() {
    val = digitalRead(inputPin); //read value of pushbutton

    if (val == LOW) { //if clause activated if pushbutton pressed and thus inputPin reads LOW
        sendLedVal = !sendLedVal; //if clause activated if pushbutton pressed and thus inputPin reads LOW
        digitalWrite(sendLedPin, sendLedVal ? HIGH : LOW); //write the appropriate HIGH/LOW to the sendLed pin to turn it ON/OFF
        Spark.publish("Core1Toggle", sendLedVal ? "ON" : "OFF"); //publish the state to the Spark Cloud as ON/OFF
        delay(250); //primitive button debouncing
    }
}

void ledTwoToggle(const char *toggle, const char *onOff){ //handler function for Spark.subscribe()
    if (strcmp(onOff, "ON") == 0){ //if sendLed on Core2 is ON according to Spark.publish()
        digitalWrite(receiveLedPin, HIGH); //then turn on receiveLed
    } else if (strcmp(onOff, "OFF") == 0){ //if sendLed on Core2 is OFF according to Spark.publish()
        digitalWrite(receiveLedPin, LOW); //then turn off receiveLed
    }
}