I have the same symptoms using a Ardulog-RTC from HobbyTronics. http://www.hobbytronics.co.uk/ardulog-rtc
Just using the supplied sketch, I soldered on a Dallas temp I2C to the board and this reports the temperature correctly via serial. However, although the LOG.001 file is created correctly, the file itself contains no data. Which is odd.
I’ve tried using Sandisk Ultra 16Gb and 32Gb cards, both of which were formatted using the SD Card Formatter as recommended in the sticky. Both cards appear to behave properly as I can save files onto them via Win10. I’ve also run the FlashDrive/Card Tester v1.14 from vconsole.com and they both check OK for the read/write test.
This is the exact card:
HobbyTronics themselves test using a small card - but I can’t readily obtain MicroSD cards less than 16Gb locally (argos/supermarkets - Asda, Sainsburys etc) unless I use preowned eBay etc. Which I don’t want to do! Their support has been good - but I’m stuck on this issue.
Does anyone out there have compatibility tests they carry out?
Incidentally, I have used both these cards on a different project with a Mega connected to a RobotDyn MicroSD card board which worked fine.
Encl: the full sketchbook including above and the other two referenced files. This is also available from the Ardulog-RTC page link above at the foot.
**Update: Tried the Datalogger Sketch from the SD examples, and that works perfectly on the same 16Gb microsd card as above. So there’s possibly a quirk with the sketch above.
ardulog_rtc.zip (5.52 KB)