bonjour,
un truc comme ca par exemple
DateTime now = rtc.now();
dataFile.print(now.year(), DEC);
dataFile.print('/');
dataFile.print(now.month(), DEC);
dataFile.print('/');
dataFile.print(now.day(), DEC);
dataFile.print(" ");
dataFile.print(now.hour(), DEC);
dataFile.print(':');
dataFile.print(now.minute(), DEC);
dataFile.print(':');
dataFile.print(now.second(), DEC)
dataFile.println(dataString);
dataFile.close();