Riffle-ito REVC: measuring RTC temp and thermistor temp, and recording values (with RTC unix timestamp) to SD card (and flashing LED); deep sleep for 5 seconds in between measurements

dwbThermistorRtcSD1LowPow.ino

#include <JeeLib.h>

 ISR(WDT_vect) { Sleepy::watchdogEvent(); }
 
 // which analog pin to connect
#define THERMISTORPIN A2       
// resistance at 25 degrees C
#define THERMISTORNOMINAL 10000      
// temp. for nominal resistance (almost always 25 C)
#define TEMPERATURENOMINAL 25   
// how many samples to take and average, more takes longer
// but is more 'smooth'
#define NUMSAMPLES 5
// The beta coefficient of the thermistor (usually 3000-4000)
#define BCOEFFICIENT 3950
// the value of the 'other' resistor
#define SERIESRESISTOR 10000    

#define outFileName "testDWB3.csv"

#include <Wire.h>

int samples[NUMSAMPLES];
int led = 6;

#include <SPI.h>
#include <SD.h>

#include <RTClib.h>
#include <RTC_DS3231.h>

RTC_DS3231 RTC;


// On the Ethernet Shield, CS is pin 4. Note that even if it's not
// used as the CS pin, the hardware CS pin (10 on most Arduino boards,
// 53 on the Mega) must be left as an output or the SD library
// functions will not work.
const int chipSelect = 7;    
int SDpower = 5;
int sensorPower = 4;


File dataFile;


 
void setup(void) {
  
  pinMode(SDpower,OUTPUT);
  pinMode(sensorPower,OUTPUT);
  digitalWrite(SDpower,LOW);
  digitalWrite(sensorPower,LOW);
  
  pinMode(led, OUTPUT); 
  
  // for i2c for RTC
  Wire.begin();
  RTC.begin();
  
  Serial.begin(9600);
  //analogReference(EXTERNAL);
  
  //eeprom
  int addr = 0;
  
  Serial.print("Initializing SD card...");
  // make sure that the default chip select pin is set to
  // output, even if you don't use it:
  pinMode(SS, OUTPUT);
  
  // see if the card is present and can be initialized:
  if (!SD.begin(chipSelect)) {
    Serial.println("Card failed, or not present");
    // don't do anything more:
    while (1) ;
  }
  Serial.println("card initialized.");
  
  
  // check on the RTC
  if (! RTC.isrunning()) {
      Serial.println("RTC is NOT running!");
      // following line sets the RTC to the date & time this sketch was compiled
      RTC.adjust(DateTime(__DATE__, __TIME__));
    }
  
    DateTime now = RTC.now();
    DateTime compiled = DateTime(__DATE__, __TIME__);
    if (now.unixtime() < compiled.unixtime()) {
      //Serial.println("RTC is older than compile time!  Updating");
      RTC.adjust(DateTime(__DATE__, __TIME__));
    }
    
    
  
}
 
void loop(void) {
  
  digitalWrite(led, LOW);
  //delay(200);
  
  Sleepy::loseSomeTime(5000);
  
  
  DateTime now = RTC.now();
  
  //get the onboard temp from the RTC
  //RTC.forceTempConv(true);  //DS3231 does this every 64 seconds, we are simply testing the function here
    float RTCTemp = RTC.getTempAsFloat();
  
  
   long unixNow = now.unixtime();
   //bSerial.println(now.unixtime());
   
    
  digitalWrite(led, HIGH);
   delay(1000);
   
  // delay(1000);
   
  uint8_t i;
  float average;
 
  // take N samples in a row, with a slight delay
  for (i=0; i< NUMSAMPLES; i++) {
   samples[i] = analogRead(THERMISTORPIN);
   delay(10);
  }
 
  // average all the samples out
  average = 0;
  for (i=0; i< NUMSAMPLES; i++) {
     average += samples[i];
  }
  average /= NUMSAMPLES;
 
  Serial.print("Average analog reading "); 
  Serial.println(average);
 
  // convert the value to resistance
  average = 1023 / average - 1;
  average = SERIESRESISTOR / average;
  Serial.print("Thermistor resistance "); 
  Serial.println(average);
 
  float steinhart;
  steinhart = average / THERMISTORNOMINAL;     // (R/Ro)
  steinhart = log(steinhart);                  // ln(R/Ro)
  steinhart /= BCOEFFICIENT;                   // 1/B * ln(R/Ro)
  steinhart += 1.0 / (TEMPERATURENOMINAL + 273.15); // + (1/To)
  steinhart = 1.0 / steinhart;                 // Invert
  steinhart -= 273.15;                         // convert to C
 
  Serial.print("Temperature "); 
  Serial.print(steinhart);
  Serial.println(" *C");
 
 
 // get RTC vals
 
 /*
  // send request to receive data starting at register 0
  Wire.beginTransmission(0x68); // 0x68 is DS3231 device address
  Wire.write((byte)0); // start at register 0
  Wire.endTransmission();
  Wire.requestFrom(0x68, 3); // request three bytes (seconds, minutes, hours)
*/

    
 // write to sd card
 
 // Open up the file we're going to log to!
  dataFile = SD.open(outFileName, FILE_WRITE);
  if (! dataFile) {
    Serial.println("error opening datalog.txt");
    // Wait forever since we cant write data
    while (1) ;
  }
  
  float temp10=steinhart*10;
  int temp10int=(int) temp10;
  
  int onboardTempInt = (int) RTCTemp*10;
  
  
  // make a string for assembling the data to log:
  String dataString = "";
  
  dataString += String(unixNow);
  dataString +=",";
  
  dataString += onboardTempInt;
  
  //dataString += String(unixNow);
  dataString+=",";
  
    
  //Serial.print(steinhart);
  dataString += String(temp10int);
  
    
   
  dataFile.println(dataString);


  
  // print to the serial port too:
  Serial.println(dataString);
  
  // The following line will 'save' the file to the SD card after every
  // line of data - this will use more power and slow down how much data
  // you can read but it's safer! 
  // If you want to speed up the system, remove the call to flush() and it
  // will save the file only every 512 bytes - every time a sector on the 
  // SD card is filled with data.
  dataFile.flush();
 dataFile.close();
 
 
  //delay(1000);
  
}

instead of using the unix timestamp, I think you can add a datetime stamp directly to the file (avoiding conversion after downloading the file). See https://github.com/adafruit/RTClib/blob/master/examples/ds1307/ds1307.pde

---

Like this but would append to dataString instead of Serial.print()

DateTime now = rtc.now();

Serial.print(now.year(), DEC);
Serial.print('/');
Serial.print(now.month(), DEC);
Serial.print('/');
Serial.print(now.day(), DEC);
Serial.print(' ');
Serial.print(now.hour(), DEC);
Serial.print(':');
Serial.print(now.minute(), DEC);
Serial.print(':');
Serial.print(now.second(), DEC);
Serial.println();