/*
 * For the Riffle Datalogger
 * The sketch logs the temperature and humidity from a DHT22 sensor and 
 * temperature from two MCP9808 I2C sensors.
 * The logging interval is editable.
 * It uses the RTC as a scheduler by using an Alarm and Interrupt
 * pin to wake up the ATmega at an interval.
 * It logs to the SD card and outputs time and values in the Serial
 * Monitor
 * Adapted by C. Fastie (6/8/16) from Kina Smith's SHT21_Logger.ino 
 */

#include <Wire.h>
#include <SD.h>
#include <SPI.h>
#include <EnableInterrupt.h>
#include <DS3231.h>             // Kina's fork
#include <LowPower.h>
#include "Adafruit_MCP9808.h"   // for the Adafruit MCP9808 temperature sensor https://www.adafruit.com/products/1782?&main_page=product_info&products_id=1782
#include <Adafruit_Sensor.h>
#include "DHT.h"                //for DHT temp and humidity sensors

DS3231 rtc; //initialize the Real Time Clock

const int led = 9; //led pin
const int bat_v_pin = A3; //battery voltage pin (1/2 of actual voltage)
const int bat_v_enable = 4; //enable pin for bat. voltage read
const int sd_pwr_enable = 6; //enable pin for SD power
const int chipSelect = 7; //chipSelect for SD card
const int RTC_INT = 5; //RTC interrupt pin

int interval_sec = 300; //Logging interval in seconds

//sensor values
float bat_v;
float DHTh;
float DHTt;
float MCP1;
float MCP2;

// DHT22 initialization
#define DHTTYPE DHT22     // DHT 22  (AM2302), AM2321
#define DHTPIN 2          // what digital pin the DHT is connected to
DHT dht(DHTPIN, DHTTYPE); // Initialize DHT sensor
#define SENSOR_MS 400     // Sensor reading delay

// Create the MCP9808 temperature sensor objects
Adafruit_MCP9808 tempsensor1 = Adafruit_MCP9808();
Adafruit_MCP9808 tempsensor2 = Adafruit_MCP9808();

void pin5_interrupt() {
  disableInterrupt(RTC_INT); //first it disables the interrupt so it doesn't get retriggered
}

//Puts the MCU into power saving sleep mode and sets the wake time
void enterSleep(DateTime& dt) { //argument is Wake Time as a DateTime object
  rtc.clearAlarm(); //resets the alarm interrupt status on the RTC
  enableInterrupt(RTC_INT, pin5_interrupt, FALLING); //enables the interrupt on Pin5
  rtc.enableAlarm(dt); //Sets the alarm on the RTC to the specified time (using the DateTime Object passed in)
  delay(100); //wait for a moment for everything to complete
  LowPower.powerDown(SLEEP_FOREVER, ADC_OFF, BOD_OFF); //power down everything until the alarm fires
}

float getBat_v(int read_p, int en_p) {
  float v;
  digitalWrite(en_p, LOW); //write mosfet low to enable read
  delay(10); //wait for it to settle
  v = analogRead(read_p); //read voltage
  delay(10); //wait some more...for some reason
  digitalWrite(en_p, HIGH); //disable read circuit
  v = (v * (3.3 / 1024.0)) * 2.0; //calculate actual voltage
  return v; 
}

void writeDataToCard(long utc, float DHTh, float DHTt, float MCP1, float MCP2, float v) {
  //open and write files to SD card
  File dataFile = SD.open("MCPDHTs.CSV", FILE_WRITE);
  if (dataFile) {
    dataFile.print(utc);
    dataFile.print(",");
    dataFile.print(DHTh);
    dataFile.print(",");
    dataFile.print(DHTt);
    dataFile.print(",");
    dataFile.print(MCP1);
    dataFile.print(",");
    dataFile.print(MCP2);
    dataFile.print(",");
    dataFile.print(v);
    dataFile.println();
    dataFile.close();
  }
}

void Blink(byte PIN, int DELAY_MS) {
  //Blink an LED
  pinMode(PIN, OUTPUT);
  digitalWrite(PIN, HIGH);
  delay(DELAY_MS);
  digitalWrite(PIN, LOW);
  delay(DELAY_MS);
}

void setup() {
  Wire.begin();
  Serial.begin(9600);
  pinMode(bat_v_enable, OUTPUT);
  pinMode(sd_pwr_enable, OUTPUT);
  pinMode(RTC_INT, INPUT_PULLUP); //RTC interrupt line requires a pullup

  rtc.begin(); //start RTC
  //  rtc.adjust(DateTime((__DATE__), (__TIME__))); //sets the RTC to the computer time.

  digitalWrite(sd_pwr_enable, LOW); //Enable power for SD card  
  if (!SD.begin(chipSelect)) {
    Serial.println("Card failed, or not present");
    while (1) {
      Blink(led, 200);
    }
  }
  
  //MCP9808 temperature sensors -- each has a different address
   if (!tempsensor1.begin(0x19)) {
    Serial.println("Couldn't find MCP9808 A0!");
    while (1);
  }
   if (!tempsensor2.begin(0x1A)) {
    Serial.println("Couldn't find MCP9808 A1!");
    while (1);
  }
}

void loop() {
  DateTime now = rtc.now(); //get the current time
  DateTime nextAlarm = DateTime(now.unixtime() + interval_sec);

  Serial.print("The Current Time is: ");
  Serial.print(now.unixtime());
  Serial.println();

//take readings
  bat_v = getBat_v(bat_v_pin, bat_v_enable); //takes 20ms

// Read DHT sensor
   float DHTh = dht.readHumidity();
// Read temperature as Celsius (the default)
   float DHTt = dht.readTemperature();

// Read MCP 1  
  tempsensor1.shutdown_wake(0);  
  float MCP1 = tempsensor1.readTempC();
  delay(250);
  tempsensor1.shutdown_wake(1); // shutdown MCP9808 
  
// Read MCP 2
  tempsensor2.shutdown_wake(0);  
  float MCP2 = tempsensor2.readTempC();
  delay(250);
  tempsensor2.shutdown_wake(1); // shutdown MCP9808 
  
  Serial.print(DHTh);
  Serial.print(", ");
  Serial.print(DHTt);
  Serial.print(", ");
  Serial.print(MCP1);
  Serial.print(", ");
  Serial.print(MCP2);
  Serial.print(", ");
  Serial.print(bat_v);
  Serial.println();
  
  //write data
  writeDataToCard(now.unixtime(), DHTh, DHTt, MCP1, MCP2, bat_v);
  Blink(led, 100);
  
  Serial.print("Sleeping for ");
  Serial.print(interval_sec);
  Serial.print(" seconds.");
  Serial.println();
  enterSleep(nextAlarm); //enter Sleep until alarm fires
}