AZDelivery 3 x DS3231 RTC Real Time Clock I2C compatible with Arduino and Raspberry Pi including E-Book!

Pros: The clock module is self contained so easy to use with I2C communications once you know the base address (0x68 or 104 decimal). Not mentioned in the description is the built in serial EEPROM giving 4 kBytes of storage, this also uses I2C communications and again you need the base address (0x57 or 87 decimal), board has three addressing links to modify the base address of the EEPROM in the range 0x50 to 0x57.Cons:Circuit has built in charging circuit so it is dangerous to use the non rechargeable batteries supplied with the device, diode on the board needs to be removed to isolate the charging circuit.No information was supplied with the unit but found schematic and address details of the two devices by searching the internet. To use the device you must know the base address of each device.There is a link in the QR Code on the card included with the delivery for the eBook, unfortunatley this does not work resulting in an error message 'There is no row at position 0.' you will need to be able to translate url to text to read this error message. Highly unsatisfactory give us a proper link not one via flyt.it that does not work.

These work great and are superb value, however i'm only giving it 4/5 because it's slightly on the bulky size, especially if you need to fit it with other components and boards into a pi or pi zero case, so if space is an issue look for a lower profile one with smaller battery, but if that's not an issue than these are ideal.

Purchased to build a WSPR beacon, I was initially quite pleased to find an SN (the more accurate 2ppm) variant amongst the three units shipped. Sadly, it doesn't work. The other two modules were M versions (5ppm) and they seem to work just fine. Don't forget to remove the 200 ohm resistor or else the lithium cell will get charged (not good). Edited the star rating because of superb customer service.

Don't buy this product. The module I received blew up my arduino. On investigation I discovered the module had a chip marked ISO3082 which is a half duplex Transceiver chip on the site where the DS3231 RTC chip should have been. As I have removed the components from the board I feel unable now to send it back but would advise seller to check the chips on this batch of modules as it's the wrong chip and will damage your arduino.

I wanted to use the RTC's in conjunction with an Arduino project, to provide Real Time Clock function and to use the square wave outputs. Of the three units only one responded properly to commands sent by an app on an Arduino board to change the frequency output on the SQW pin. The two faulty units did show clock function but the frequency of the 32kHz out put was nowhere near the specified 32768 Hz.

Working well easy to setup... I've modified one of them by removing the resistor to stop it charging the battery..great price too.

Hi,I’m making a special clock for my sister and needed an RTC which was more accurate and wouldn’t loose time like the cheaper versions. This works a treat and has built in alarm function and fully interfaces with my Arduino project.

I made a Small oled clock . The rtc works perfectly . If you are soldering it to a pcb replace the header pins