DS1302 Clock Module Real-Time Clock Module RTC for Arduino AVR ARM

I received all DS3231M marked chips. I've used a lot of these modules over time and the DS3231N are usually mis-marked DS3231M chips. You can tell because the M does not have a variable frequency clock output (SQW pin) and the N does. In the more than a dozen modules I've only found two genuine DS3231N chips.Also, the M is spec'd at ±5PPM accuracy and the N is ±2PPM.Mis-marked chips are common.

The units I was sold do not output 5v DC on the 5v pin. It outputs about 0.83V.I've tried multiple USB A <-> USB C cables, all to no avail.

The SQW was tricky to get working. This is the only code that worked to set up the SQW. // set up the square wave. Wire.beginTransmission(0x68); Wire.write(0x0E); Wire.write(0x00); Wire.endTransmission();

These are great & easy to use.I am using library <DS3232RTC.h>

Purchased these for the components on the PCB since it was cheaper than buying the components on their own. It worked great right out of the box and has reliable kept the time so far. With multiple tests of power cycles, the trickle battery has kept the time accurately.

Yes, they work, but it's not a stable and accurate Real Time Clock module. I wanted to build a ham radio UTC clock, but it just doesn't quite do the job when the power is off and the battery is powering the module. I found it can be off by several minutes in a 24RH period.

I bought these for a college lab project. Worked great!! The tinyGPS.h library works on Arduino and ESP32 flawlessly. :-)

The price was OK for the DS3231/EEPROM module with the CR2032 Lithium battery. The SMD parts have been infrared soldered (as opposed to riskier hand soldering). The batteries have been installed (my guess based on code date is over 1 year). Normally there is a piece of thin plastic with a "pull tab" that insulates them from running. Alternately, the battery is packaged separately and installed by the user. Product photos give the impression that the batteries are not installed when purchased.