Sensor Array with RedBear Duo and Particle Cloud

// ------------
// Read Moisture Sensors on RedBear and send data to Particle Cloud
//
//      Features:
//          1) Detect number of sensors connected
//          2) Use Sleepmode to go reduce power consumption
//
//      Notes:
//
//          Sensor 0 is on D0/A0, Sensor 1 is on D1/A1 and so on
//          We are not using D7 as this is used by internal LED which we are using indicator that reaading is in progress
//
//          As the code executes quite quickly and goes straight into sleep, you might find it difficult flashing new firmware.
//          Recommend to start off with sleep commented out - you will need to hit reset button to trigger new reading.
//          Sleep is commented out by default (Line 114)
//
//          Alternative is to wait for device to go to sleep, and flash firmware.
//          Then press and hold RESET + SETUP button, the let go of RESET until white or purple light comes back.
//
//      19 December 2018 
//      Author: dante@serveronthemove.com.au
//      Hardware: RedBear Duo
//      Firmware: v0.3.3 - should work with earlier versions
//
//      Sensors: 4 pin Moisture sensor with Analog output
//
//       Wiring:
//          Moisture Sensor -> RedBear Duo
//          GND             -> GND
//          VCC             -> Dx
//          DO              - Not used
//          AO              -> Ax
//
//          For example, using two sensors
//              Sensor 1 uses A0 and D0
//              Sensor 2 uses A4 and D4
//          The code will automatically detect the sensors, however it is important that Analog and Digital are aligned.
// ------------

/*
 declare variables
*/
const int numberOfSensors = 7; // how many sensor are we be scanning
const int settleIv = 2000; // how long to wait between turning sensor on and reading from sensor
const int sensorThreshold = 300; // For connected sensors the value read (when turned on) should be below threshold. Used to detect if sensor connecte
const int secondsSleep = 60; // amount of seconds RedBear Duo should go to sleep

const String seperator = ","; // seperator to be used 

String sensorName = "Patch0/Sensor"; // Sensorname to send to Particle.io Cloud
String sensorReadings = ""; // holds the sensor readings per loop

//
// Sensor Array Configuration
//
int moistureSensorSetup[7][2] = {{D0,A0},{D1,A1},{D2,A2},{D3,A3},{D4,A4},{D5,A5},{D6,A6}}; // Digital (power on/off) and Analogue (read value) couples 


// bug in Particle Cloud for firmware 0.3.3 - LED_BUILTIN is not defined, hence below workaround
// -- workaround start
#ifndef LED_BUILTIN
    #define LED_BUILTIN 7
#endif
// -- workaround end

void setup() {
    // Turn D7/LED_BULTIN on to indicate that reading/processing is taking place. Will be useful when putting setup into case to provide user feedback
    digitalWrite(LED_BUILTIN, HIGH);

    // loop through all sensors and set the PINs up
    for (int i = 0; i < numberOfSensors; i++) {
        // setup D as output to power esnor, and A as input to read the value
        pinMode(moistureSensorSetup[i][0],OUTPUT); // We are setting DX to outout
        // no need to set the ADC's as output - will be done implicit by analogRead()
        
        // test if sensor is connected - (values under the defined threshold when turned off)
        digitalWrite(moistureSensorSetup[i][0],LOW);
        
        // initialise SensorRead    
        int sensorRead = 0;

        // only if Sensor is connected
        if (analogRead(moistureSensorSetup[i][1]) < sensorThreshold) {
            // turn the sensor on, by setting digital pin to high
            digitalWrite(moistureSensorSetup[i][0],HIGH);
            
            // wait for sensor to settle
            delay(settleIv);

            // read sensor value from Analog Port
            sensorRead = analogRead(moistureSensorSetup[i][1]);

            // turn sensor off
            digitalWrite(moistureSensorSetup[i][0],LOW);
        }

        // add a seperator to list if there has been a previous value
        if (sensorReadings != "") {
            sensorReadings = sensorReadings + seperator;
        }            

        // append the sensor reading
        sensorReadings = sensorReadings + String(sensorRead);
    }
    
    // once all sensors have been read, publish sensor values to cloud
    Particle.publish(sensorName, sensorReadings, 3600, PRIVATE);

    // Turn D7/LED_BULTIN off to indicate process is done
    digitalWrite(LED_BUILTIN, LOW);

    // disable line below when developing, as otherwise it will go immediately to sleep post processing and will make
    // flashing difficult.
    //System.sleep(SLEEP_MODE_DEEP, 60);
}

// we are not doing anything in loop as waking from sleep will restart (startup executed again)
void loop() {
    // intentionally empty
}