AITRIP 3PCS DS3231 Real Time Clock Module RTC Sensor High Precision AT24C32 IIC Timer Alarm Clock for Arduino Raspberry Pi

Works great! I'm using an Expressif ESP32S3DevKitC-1 and a 0.96" OLED display. 3.3 volts from the ESP32S3 power the RTC and the display.

I got this module because I was getting constant errors about my time not being synchronized. I tried everything I could from setting NTP to installing various distros such as Ubuntu, Ubuntu Server, RaspiOS and Dietpi but nothing worked until I got this module.So, look no further and grab this if you need to have your time in sync.As a side note, if you are using a Raspberry Pi, please connect the module like this:VCC --> 5VSDA --> Pin3SCL --> Pin5GND --> Pin6Also, you need to use a rechargeable battery such as the LIR2032.I hope this helps.

If you buy these check the markings on the DS3231 chips. If the chip is NOT a DS3231SN chip, then it will not keep time as you expect it to! It is advisable to return any NON DS3231SN chips, as they don't keep time any better than DS1307 chips.The crude charging circuit on the board is a fire hazard, regardless of the battery type you choose to use.When using 3.3V, Lithium batteries do not charge at all. When using 5V, the charging voltage is too high and (over time) the battery can bulge or explode. To avoid this, remove the resistor marked 201 or the diode (glass and looks orange-ish) or both, and any standard CR2032 battery will give you years of use.I am attaching a schematic and a photo showing the components to remove. Be certain you have a unit you want to keep BEFORE you make these changes, as you cannot return the item after doing so.

It comes without a battery.

The description of this item is deceiving. It states you will receive the SN chip, describes all of the capabilities and workings of an SN, and then in little text down at the bottom says they ship the SN, N and M at random - text I did not see until opening all 3 packages. Inconveniently I received all Ms, the cheapest and least reliable of the 3, it looses the most time and does not use a crystal oscillator. Additionally the M requires regular batteries, not rechargeable like the others, so I had to cancel an order for the LIR2032s. Theres no way to guarantee which model you get, so order at your own risk if you specifically need the SN. My project will be fine with an M, but I am not excited about it. Otherwise, the product is at least an RTC module, just not one that meets the exact specifications on 90% of this listing. Please be aware, that despite the picture this does not come with batteries. Which batteries you need will depend on which model you randomly receive.

This is a bargain priced piece of electronics. I got the project box from Amazon:https://www.amazon.com/dp/B07RTYYHK7?ref=ppx_yo2ov_dt_b_product_details&th=1It is extremally accurate so there is no need for adjustments.One reviewer wrote the Vcc pin is not active, totally wrong. When Vcc applied the LED on the clock comes on.Getting the firmware was a bit time consuming since I hadn't used the IDE and had to update it, there were some conflicts with libraries (LCD libraries).I recommend it.

Work great and I like that these have a replaceable coin cell battery. My first one years ago had a permanently fixed battery.

These RTC work great on my Pico Microcontroller project. Easy to set up.