HiLetgo 5pcs DS3231 AT24C32 Clock Module Real Time Clock Module IIC RTC Module for Arduino Without Battery

There are Arduino (thus Particle) libraries for these RTCs. The code is straight forward and anything you need to know about the time, date, DoW, etc. is there. It's a powerful little RTC chip.

Whether it be for a prototype or just some bread boarding, this module is simple to use, well supported by different development environments, and accurate. It's well made and will treat you right!

IMPORTANT BATTERY INFO! DO NOT USE 5V VCC!-----------------------------------------------------------These all worked great, but be SUPER careful, this charges at 5V so it popped my batteries and fried my Arduino MEGA board, OLED and my Bluetooth module. I made some adjustments and added a PIR sensor and when I reconnected it, I inadvertently connected the RTC to 5V and you see the picture, POP! Took about a month or so, but just be careful. I'm using only 3.3V now for about 8 months, all good.ON THE RTC ITSELF-------------------------------------As far as the unit, it's solid. They been living in a PVC box outside with a cooling fan (FL so it's hot and humid) and they are holding up great. I use them to verify time for lighting and for irrigation scheduling so it's kinda important it stays accurate.The temperature seems a bit high sometimes (mine had a getTemp() function) but I'm not sure if it's just the location or the sensor itself. I'll need to test it with an external thermometer but I have a temp/humidity sensor I'm using separate anyway so I don't depend on the RTC temp that much. More of a second look at temp.So no issues for me with the RTC and its functions at all. You obviously need a library to use it and will need to write some basic functions to extract time, compare time, etc. Those are not in the basic library as far as presentation type output.

These clock modules work well with Arduino or Raspberry Pi projects, there are readily-available open source libraries for both. Accuracy is very good as one would expect from a temperature-compensated crystal oscillator (which is internal to the IC). It has two alarms, one with seconds resolution and the other with minutes resolution.The IC can provide (optionally, not active by default) a 32KHz reference clock, and either a programmable-frequency square-wave output or an alarm-interrupt output.I've not used the on-board EEPROM in any of my projects, but it's there and visible on the I2C bus.You can read the temperature value from the on-chip calibration sensor, it's not super high resolution, but good enough as a rough temp sensor.A couple things to look out for:1) This board has a diode and resistor that will attempt to charge the battery from the VCC source, if VCC is high enough to overcome the diode drop. Probably not a huge issue with 3.3V systems, more so with 5V. The current is low, but it's generally considered bad form to try charging lithium coin cells (the IC on this board is explicitly certified to NOT charge the battery). If you intend to use such a battery, the diode can be removed to disable this function. If you want to use a supercapacitor backup, keep it.2) Alarms don't work without VCC present. It will set the alarm flag, but the open-drain I/O pin will not be asserted until VCC is applied. This is expected, that's how the IC works, but if you want a clock that can run exclusively from the coin battery and wake up your CPU with an alarm, this isn't it. Interestingly, it CAN provide the square-wave output when running on the battery.

These little modules are outstanding. Not only do they keep excellent time but have a temp sensor and even extra storage you can use for storing needed variables etc.. I've already used 4 of the 5. Now all my projects know exactly what time it is. Critical when you're logging data.just sync them up with time.windows.com

The module is perfect for my project. I just wish it didn't have the 2.54mm pin header pre-soldered in place. I just need to have the pins in a different orientation. Therefore, it would be easier if I didn't have to de-solder these to install what I need, but I'm not going to remove any stars for that as the way it comes stock works great on a breadboard.

worked great w/ T Display S3s - just ensure you get rechargeable batteries for it will try to charge the coil cell. I have about 10 of these deployed so far w/o any fall out or issues

Ok - this unit is HUGE - it's bigger than my Arduino Nano and magitude larger than the ATTINY. That's mainly due to the battery selection CR3220 which is HUGE but on the other hand, it makes it easy to get and replace batteries.Hookup is EASY - i2c is a simple protocol to use on any Arduino (just look up the pins on your model) and RTClib will connect and use the unit very easily.The issue is keeping the time once set. I'd created several items that needed time over the last month so I've used several of these RTC units to keep time. However, after even a day there's a very big drift in time - several minutes, at times several 10s of minutes! This means there's really no point to that huge battery - the unit would do better using network time that would be adjusted every so often during the day.The last issue is power consumption. It's HUGE - a large power led shines and wastes mAs galore when running. Of course if you're just starting out, the LED may be helpful to see things are turned on, but as I've had to build little project boxes for my things, I find this unit too large and too power-hungry, on top of not being able to keep time. So for practical time use, I'm looking at the Nano33 IoT which has RTC built in and other solutions where power consumption is low and size even so.