Ground - ping on change

/*******************************************************************************
 *  GROUND code
 *  looks for substancial change from sensors
 *
 *  Publishes: ping
 *  Subscribes: NA
 *
 *  Setters:
 *  - setBrightness(String val)
 *  - setSpeed(String val)
 *  Convention for setters, return 1 if successful, -1 otherwise
 *
 *  Published Variables:
 *  - int lastPing // i think its better deleting? check possible functionality
 *
 *  Extension:
 *  - wifi status
 *  - runtime and battery status
 *  Built for Photon, no dependecies
 *
 *******************************************************************************/

/*
 *  Every refresh the arduino looks for substancial
 *  change in any pin since last
 *  Should investigate sleep function to save photon battery
 *  https://github.com/spark/firmware/issues/655
 *
 *  You get also a battery status report and last time since ping
 *  http://community.particle.io/t/name-resolving-of-tcpclient-when-connecting-to-other-photon-running-mdns/24843/2
 *  http://community.particle.io/t/sample-code-for-connecting-2-photons-wifi-direct/21386/7
 *  https://community.particle.io/t/real-time-communication-between-two-photons-on-internet/15053/5
 */

 #define LED_PIN D7 // onboard LED pin
 #define WAIT 1000
 #define WAIT2 500


int pins[]   = {A0, A1, A2, A3};
int numInput = sizeof(pins) - 1;//  sizeof(myPins) / sizeof(myPins[0]); // check this
int lastSum  = -1;

int thresh    = 1000; // amount of difference to tolerate;
bool ignore   = false; // ignore one cycle

SYSTEM_MODE(AUTOMATIC);
STARTUP(WiFi.selectAntenna(ANT_AUTO)); // continually switches at high speed between antennas

void setup() {


  /* Initialize analog ins */
 for (int i = 0; i < numInput; i++) {
    pinMode(pins[i], INPUT);
 }

 /* Initialize led pin */
 pinMode(LED_PIN, OUTPUT);
 pinResetFast(LED_PIN);

 /* Turn off on board LED */
 RGB.control(true);
 RGB.color(0, 0, 0);

 Particle.variable("LDRsum", &lastSum, INT);
 // https://api.particle.io/v1/devices/1b0022001947353236343033/LDRsum?access_token=e9ff4e5ec3b85e66f7e50e1c0e2fa606d0722c02

 Particle.function("setThresh", newThresh); // sets a new threshold

}

void loop() {

    int sum = 0;
    if (!ignore) {
        for (int i = 0; i < 6; i++){
            int myVal = analogRead(pins[i]);
            sum += myVal;
        }

        int diff  = abs(lastSum - sum);
        if (diff > thresh) {
            char publishString[4];
            sprintf(publishString,"%u", diff);
            // how do i make it private
            Particle.publish( "ping", publishString, 60, PRIVATE );  // event name, data, TTL, status
            ignore = true;
        }
        lastSum = sum;
        delay(WAIT2);
    }
    ignore = false;
    delay(WAIT);

}

int newThresh(String command) {
    /* Particle.functions always take a string as an argument and return an integer. */
    // sets new threshold value
    thresh = command.toInt();
    return 1;
}