Is my Realtime Clock Locking Up My Arduino? If so, how would I solve it?

Question

I am having a very strange issue with the realtime clock in Arduino that I cannot seem to solve. Basically, I have a program that logs data from a terrarium kit and saves each session to an SD card as a file named after the time the program started. 0

The problem with the program is that the code hangs on the statement before the setup section: "DateTime now = RTC.now()." The realtime clock appears to be functioning correctly with the example program which makes this issue even more strange. I am unsure if this is purely a software or hardware issue. From scouring the internet, I have found people with a similar problem to mine where the RTC will freeze up the i2c bus on the Arduino. However, I am unsure whether this is the issue plaguing me. If this is indeed the issue plaguing my program, unsure of how to work around it. I found an online solution here, however my program freezes upon launch so this would not work for me.

So far, I have tried: -Replacing the coin-cell battery in the realtime clock (I am using 3 volt batteries) -Replacing the datalogger shield with a new one -Replacing the Arduino with a new one -Checking to make sure that the jumpers were correctly soldered to the datalogger shield (Adafruit support checked mine through images and said they looked good)

I am running this program on IDE Version 1.6.9 with a program with the newer Adafruit datalogger shield on the Arduino Mega.

Any help would be greatly appreciated

//The libraries we need for our terrarium kit
//Download and install them all at this link: https://drive.google.com/drive/folders/10XAFdYmnyz0dg9I6YYj80vJlHebFIZhN
#include <OneWire.h> //Import OneWire library
#include <DallasTemperature.h> //Import DallasTemperature library
#include <Adafruit_Sensor.h> //Import Adafruit Sensor library
#include <DHT.h> //Import first part of the DHT library
#include <TimerOne.h> //Import TimerOne library
#include <SPI.h>
#include <SD.h> //this refers to an old SD library needed specifically for 
#include "RTClib.h" //this is from the rtc example folder code
//SD Card & Realtime Clock: Initialization
File logfile;
RTC_DS1307 RTC;
//Humidity Sensor: Constants
//This #define defines the pin that the DHT is plugged into
#define DHT_PIN 2 
//This #define defines the type of the DHT
#define DHT_TYPE DHT22
//This tells the code that a DHT is plugged into port DHT_PIN and the DHT is of type DHT_TYPE
DHT dht(DHT_PIN, DHT_TYPE);
//Moisture Sensor: Variables
int MS_sigPin = A5; //Set the signal pin as analog pin 5
int MS_digPin = 7; //Set the digital pin as 2
float MS_upper = 0; //Declare highest value variable
//Other variables
int measurementNumber = 1; //Number of measurements taken
//Filename:
 DateTime now = RTC.now(); //Initialize the RTC
// String seconds = (String)(now.second()); //Stores the seconds from the RTC upon setup as a string
 const String minutes = (String)(now.minute()); //Stores the seconds from the RTC upon setup as a string
 const String hours = (String)(now.hour()); //Stores the seconds from the RTC upon setup as a string
 const String days = (String)(now.day()); //Stores the seconds from the RTC upon setup as a string
 const String months = (String)(now.month()); //Stores the seconds from the RTC upon setup as a string
 const String years = (String)(now.year()); //Stores the seconds from the RTC upon setup as a string
 const String filename = "D_" + minutes + hours + days + months + years; //Create the file name as a timestamp
void setup() {
 int chipSelect = 10; //chipSelect pin for the SD card
 // put your setup code here, to run once:
 Serial.begin(115200); //Set the baud rate at 56700
//If RTC is already updated, the below is commented out
 RTC.begin();
 RTC.adjust(DateTime(F(__DATE__), F(__TIME__)));//this is to force rtc update
// if (!RTC.isrunning()) {
// 
// Serial.println("RTC is NOT running! Starting it now.");
// RTC.adjust(DateTime(F(__DATE__), F(__TIME__)));
// 
// }// end rtc if
//{
//The below is copied from wired, contains a second try, hoping for sd success herein.
 pinMode(chipSelect, OUTPUT);
 digitalWrite(chipSelect, HIGH);
 SD.begin(chipSelect);
// if (!SD.begin(10, 11, 12, 13)) {
// Serial.println("Card failed, or not present");
// delay(50);
// Serial.println("Trying again...");
// if (!SD.begin(50, 51, 52, 53)) {
// Serial.println("Card failed, or not present");
// }
// }
 /******************************** CSV FORMAT ******************************/
// Serial.print("Current Position: ");
// Serial.println(logfile.position());
 if(logfile.position() == 0)//Below print header line for datafile
 logfile.println("Unix Time, Date, Time, Light, Humidity, Temperature");
 //logfile.println("uni,date,time,Temperature");
 /**************************************************************************/
// sensors.begin();
// sensors.setResolution(12);
 //Humidity Sensor:
 dht.begin();
 //Moisture Sensor:
 pinMode(MS_sigPin, OUTPUT); //Set the signal pin as an output
 pinMode(MS_digPin, OUTPUT); //Set the digital pin as an output
 digitalWrite(MS_digPin, HIGH); //Turn the digital pin on
 Serial.println("DIP THE MOISTURE SENSOR IN A CUP OF WATER MAKING SURE NOT TO SUBMERGE THE TOP OF IT INTO THE WATER, ENTER IN ANY KEY WHEN YOU ARE READY TO CALIBRATE"); //Print out useful information
 while (Serial.available() == 0) //Hang the program until the user inputs a key to continue
 {
 }
 Serial.println("Starting Calibration"); //Print out useful information
 Timer1.initialize(1000000); //Initialize an interrupt every 1 second
 Timer1.attachInterrupt(Calibrate); //When the interrupt is called run the "Calibrate" function
}
//Calibrate the moisture sensor
void Calibrate() //Function to calibrate the sensor
{
if (analogRead(MS_sigPin) > MS_upper) //If the value read by the sensor is higher than the past highest value
{
 MS_upper = analogRead(MS_sigPin); //Set the current value as the new highest value 
 }
}
void loop() {
//Photocell: Variables
int photocellPin = A0; // the cell and 10K pulldown are connected to a0
 char fileCharStorage[(filename.length()+5)]; //+4 Characters to include ".csv"
 filename.toCharArray(fileCharStorage, filename.length()+5);
 fileCharStorage[filename.length()] = 'V'; //Set the file name
 fileCharStorage[filename.length()-1] = 'S'; //Set the file name
 fileCharStorage[filename.length()-2] = 'C'; //Set the file name
 fileCharStorage[filename.length()-3] = '.'; //Set the file name
 Serial.println(filename); //Print out the filename
 Serial.println(sizeof(fileCharStorage)); //Print the length of the array storing the file name 
 logfile = SD.open(fileCharStorage, FILE_WRITE); //Creates (or opens) a file names "MMHHDDMMYYYY.CSV"
 if (logfile)
 {
 Serial.println("The SD Card is functioning properly");
 }
 else
 {
 Serial.println("A Critical Error occured while trying to initialize the SD Card!");
 }
 //Realtime Clock
 DateTime now = RTC.now();
 //Photocell:
 int photocellReading = analogRead(photocellPin); //Variable that stores the amount of light detected by the photocell as an integer
 // This code gets the humidity from the DHT
 float dhtHumidity = dht.readHumidity();
 /*
 This code gets the temperature from the DHT
 */
 float dhtTemperature = dht.readTemperature();
 Serial.println(""); //Text Formatting
 Serial.println("Starting New Measurement (" + (String)measurementNumber + ")");
 Serial.println(""); //Text Formatting
 delay(1000);
 //Print out data from the number of measurements taken
 Serial.println("The Arduino has been active for " + (String)((measurementNumber*10)-10) + " seconds");
 measurementNumber++;
 //Print out data from the RTC
 Serial.print("Unix Time (Seconds since 1/1/1970): ");
 Serial.print(now.unixtime()); // seconds since 1/1/1970
 Serial.println(", ");
 Serial.print("RTC time: ");
 Serial.print(now.month(), DEC);
 Serial.print("/");
 Serial.print(now.day(), DEC);
 Serial.print("/");
 Serial.print(now.year(), DEC);
 Serial.print(",");
 Serial.print(now.hour(), DEC);
 Serial.print(":");
 Serial.print(now.minute(), DEC);
 Serial.print(":");
 Serial.print(now.second(), DEC);
 Serial.println("");
 Serial.println("");
 //Photocell:
 Serial.println("Data from the photocell:");
 Serial.print("Analog reading = ");
 Serial.print(photocellReading); // the raw analog reading 
 if (photocellReading < 10) { 
 Serial.println(" - Dark"); //says that if any number is lower than 10 then it prints out dark.
 } else if (photocellReading < 200) {
 Serial.println(" - Dim"); //says that if any number is lower than 200 then it prints out dim.
 } else if (photocellReading < 500) { 
 Serial.println(" - Light"); //says that if any number is lower than 500 then it prints out light.
 } else if (photocellReading < 800) { 
 Serial.println(" - Bright"); //says that if any number is lower than 800 then it prints out bright
 } else { 
 Serial.println(" - Very bright"); //says that if any number higher than 800 then it prints out very bright
}
 Serial.println("");
// Humidity Sensor:
 Serial.println("Data from the humidity sensor:");
 Serial.print("Humidity: ");
 Serial.print(dhtHumidity);
 Serial.print(" %, Temp: ");
 Serial.print(dhtTemperature);
 Serial.println(" Celsius");
 Serial.println("");
 //Moisture Sensor:
 Serial.println("Data from the moisture sensor:");
 float percent = (analogRead(MS_sigPin)/MS_upper)*100; //Calculate moisture percentage
 Serial.println("Moisture = " + (String)percent + "%"); //Print out the moisture percentage
 Serial.println("");
 Serial.println("--------------------------------------------------");
 //Log everything onto the SD card
 logfile.print(now.unixtime()); // seconds since 1/1/1970
 logfile.print(", ");
 logfile.print(now.month(), DEC);
 logfile.print("/");
 logfile.print(now.day(), DEC);
 logfile.print("/");
 logfile.print(now.year(), DEC);
 logfile.print(",");
 logfile.print(now.hour(), DEC);
 logfile.print(":");
 logfile.print(now.minute(), DEC);
 logfile.print(":");
 logfile.print(now.second(), DEC);
 logfile.print(", "); 
 logfile.print(photocellReading);
 logfile.print(", "); 
 logfile.print(dhtHumidity);
 logfile.print(", "); 
 logfile.print(dhtTemperature);
 logfile.println(); 
 logfile.close();
// Delay by 1+9 (10) seconds between measurements
 delay(9000);
}

Answer 1

I'm guessing that you can't call RTC.now() before setup like that.

It would be helpful if you told us what RTC you were using, and provided a link to the library you were using for it.

At a guess, since I don't have that info, you should probably change the declaration like this:

 //Filename:
 DateTime now;

And then in your setup():

RTC.begin();
if (!RTC.isrunning()) {
 Serial.println("RTC is NOT running! Starting it now.");
 RTC.adjust(DateTime(F(__DATE__), F(__TIME__))); 
} // end rtc if
now = RTC.now(); //Initialize the RTC