File not created when file path is converted Character array type... SD.h

Other Hardware Storage
1

Hello,
I intend to use RTC module to generate real-time date and time and assign those integer values to create new file in SD card for my data logger project. i converted the integers into string and then to character array and used with SD.open(); but i am unable to create the file in SD card. following is my code. Kindly suggest...

Thanks

#include <Wire.h>
#include "RTClib.h"
#include <SPI.h>
#include <SD.h>

RTC_DS1307 rtc;

const int chipSelect = 4;
char daysOfTheWeek[7][12] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  if (! rtc.begin()) {
    Serial.println("Couldn't find RTC");
    while (1);
  }
  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(F(__DATE__), F(__TIME__)));
    // This line sets the RTC with an explicit date & time, for example to set
    // January 21, 2014 at 3am you would call:
    // rtc.adjust(DateTime(2014, 1, 21, 3, 0, 0));
  }
  Serial.print("Initializing SD card...");
  if (!SD.begin(chipSelect)) {
    Serial.println("Card failed, or not present");
    // don't do anything more:
    return;
  }
  Serial.println("card initialized.");
}

void loop() {
  // put your main code here, to run repeatedly:
  DateTime now = rtc.now();
  String fname = String (now.day()) + "/" + String (now.month()) + "/" + String (now.year()) + "_" + String (now.hour()) + ":" + String (now.minute()) + ":" + String (now.second()) + String (".txt");
  char filename[30] = {0};
  fname.toCharArray(filename, 30);
  
  File dataFile = SD.open(filename, FILE_WRITE);
  // if the file is available, write to it:
  if (dataFile) {
    dataFile.println("File created successfully @ " + fname);
    dataFile.close();
    // print to the serial port too:
    Serial.println("File created successfully @ " + fname);
  }
  // if the file isn't open, pop up an error:
  else {
    Serial.println("error opening " + fname);
  }
  Serial.println(filename);
  while(1){}
}

test_RTC_SD.ino (1.74 KB)

2

What is an example of the file name you are trying to create?

For today, it looks like you are trying to create a file called 18/4/2018_5:15:30.txt.

Count how many characters that is. Does that LOOK like the supported 8.3 format?

3

And I would suggest to stay away from forbidden characters like / and \

By the way, PaulS' example would be directory 18, sub-directory 4, file 2018_5:15:30.txt on a Linux / Mac system.

4 
void getFileName(){
sprintf(filename, "%02d%02d%02d.csv", year, month, day);
}