Ximimark 2PCS Data Logger Module Logging Shield Data Recorder DS1307 for Arduino UNO SD Card

EDIT: I never found any more DS3231's apart from the two units noted in my original review! All units I've received subsequently, through a few different vendors on Amazon, worked fine with code compiled for a DS1307. I'm sorry but I haven't been able to figure out where the oddball units came from, and must dial back my RTC advice to this:If your RTC seems malfunctioning (with the mandatory coin cell in place), try tweaking your sketches to declare a different module type, or running the sample/demo sketches for other types.Otherwise:PRO: Accepts full-size SD cards! I like this because I sometimes retrieve logger data outdoors at night, and micro-SDs are sure easy to not find when I get back to the house.CON: (1) No "CON" comments will ever reach the manufacturer. Some of these cards show the name "Deek-Robot" on the back silkscreen, and some don't; some Amazon vendors show product photos without the name, but it's on the actual card anyway; but it's bad news any way you look at it, because that company no longer shows the slightest clue that they were ever in that business.(2) The soldering on the stacking-type pin headers is no better than I'd have done myself. I'd rather they had left them separate. And yet it is even OK in a way: the dripped-up-the-pins solder imposes just about the same vertical offset that a shield needs if you're stacking atop an Uno clone that has a full-size USB-B jack. Without that little extra soft metal on the pins, it would fit less snugly. In that situation; but that's my situation.(3) As noted by others, the pins are flimsy.(4) No mounting holes. They're sacrificed to provide more prototyping area (relative to Adafruit's design). I'd have called this a PRO, *if* the pins had been robust enough to accept the responsibility of holding the logger firmly onto the Uno. But back to (3): those pins are flimsy.

These are great. Just what I needed.

They work fine with a UNO, but neither the RTC or the SD work with a MEGA. I realize there is some differences in the pin numbers and the code. I tried all the combinations I could find on the internet with no luck after trying multiple MEGAs.

No docs. Found some sample code for a datalogging shield, but am suspecting that the pin assignments are different.Also the headers that plug on to Arduino are really flimsy - its quite difficult to put the shield on the Arduino. Sturdy pins would have been nice.In sample code I found there was a flaw where the time didnt get set,. Had to add this: if (! RTC.isrunning()) { Serial.println("RTC is NOT running, let's set the time!"); // When time needs to be set on a new device, or after a power loss, the // 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)); }