# Adafruit DS3231 Precision RTC Breakout ## Overview ![](https://cdn-learn.adafruit.com/assets/assets/000/103/727/medium800/components_DS3231_top.jpg?1628094646) The datasheet for the DS3231 explains that this part is an "Extremely Accurate I²C-Integrated RTC/TCXO/Crystal". And, hey, it does exactly what it says on the tin! ±2ppm accuracy from 0°C to +40°C. This means ±1 minute/year. This Real Time Clock (RTC) is the most precise you can get in a small, low power package. ![](https://cdn-learn.adafruit.com/assets/assets/000/103/728/medium800/components_DS3231_back.jpg?1628094672) [We've had a breakout board version of this RTC for a while](https://www.adafruit.com/product/3013). We want to make it even easier for folks to use, so [now it also comes with STEMMA QT connectors](https://www.adafruit.com/product/5188) for plug-and-play simplicity. Be sure you buy the correct version you wish to use. ![](https://cdn-learn.adafruit.com/assets/assets/000/030/360/medium800/components_3013_quarter_ORIG.jpg?1454534810) Most RTC's use an external 32kHz timing crystal that is used to keep time with low current draw. And that's all well and good, but those crystals have slight drift, particularly when the temperature changes (the temperature changes the oscillation frequency very very very slightly but it does add up!) This RTC is in a beefy package because the crystal is _inside_ the chip! And right next to the integrated crystal is a temperature sensor. That sensor compensates for the frequency changes by adding or removing clock ticks so that the timekeeping stays on schedule ![](https://cdn-learn.adafruit.com/assets/assets/000/030/357/medium800/components_3013_iso_ORIG.jpg?1454534769) This is the finest RTC you can get, and now we have it in a compact, breadboard-friendly breakout. With a coin cell plugged into the back, you can get years of precision timekeeping, even when main power is lost. Great for datalogging and clocks, or anything where you need to really know the time. To make life easier so you can focus on your important work, we've taken the sensor and put it onto a breakout PCB along with support circuitry to let you use it with 3.3V (Feather/Raspberry Pi) or 5V (Arduino/ Metro328) logic levels. Additionally, since it speaks I2C you can easily connect it up with two wires (plus power and ground!).  We've even included [SparkFun qwiic](https://www.sparkfun.com/qwiic) compatible** [STEMMA QT](https://learn.adafruit.com/introducing-adafruit-stemma-qt)** connectors for the I2C bus so  **you don't even need to solder!**  [**QT Cable is not included** , but we have a variety in the shop](https://www.adafruit.com/?q=stemma+qt+cable&sort=BestMatch). Just wire up to your favorite micro and you can use our [CircuitPython](https://github.com/adafruit/Adafruit_CircuitPython_DS3231)/Python or [Arduino drivers](https://github.com/adafruit/RTClib) to easily interface with the DS3231. ![](https://cdn-learn.adafruit.com/assets/assets/000/103/726/medium800/components_DS3231_STEMMA_side.jpg?1628094628) Comes as a fully assembled and tested breakout plus a small piece of header. You can solder header in to plug it into a breadboard, or solder wires directly. A coin cell is required to use the battery-backup capabilities! We don't include one by default, to make shipping easier for those abroad, [but we do stock them so pick one up or use any CR1220 you have handy.](https://www.adafruit.com/products/380) Info: ![](https://cdn-learn.adafruit.com/assets/assets/000/030/359/medium800/components_3013_kit_ORIG.jpg?1454534798) - [Next Page](https://learn.adafruit.com/adafruit-ds3231-precision-rtc-breakout/pinouts.md) ## Featured Products ### Adafruit DS3231 Precision RTC Breakout [Adafruit DS3231 Precision RTC Breakout](https://www.adafruit.com/product/3013) The datasheet for the **DS3231** explains that this part is an "Extremely Accurate I²C-Integrated RTC/TCXO/Crystal". And, hey, it does exactly what it says on the tin! This **Real Time Clock (RTC)** is the most precise you can get in a small, low power... In Stock [Buy Now](https://www.adafruit.com/product/3013) [Related Guides to the Product](https://learn.adafruit.com/products/3013/guides) ### CR1220 12mm Diameter - 3V Lithium Coin Cell Battery [CR1220 12mm Diameter - 3V Lithium Coin Cell Battery](https://www.adafruit.com/product/380) These are the highest quality & capacity batteries, the same as shipped with the iCufflinks, iNecklace, Datalogging and GPS Shields, GPS HAT, etc. One battery per order (you'll want one battery per cufflink or pendant.) Brand may vary but all battery brands are verified... In Stock [Buy Now](https://www.adafruit.com/product/380) [Related Guides to the Product](https://learn.adafruit.com/products/380/guides) ### Adafruit DS3231 Precision RTC - STEMMA QT [Adafruit DS3231 Precision RTC - STEMMA QT](https://www.adafruit.com/product/5188)   The datasheet for the **DS3231** explains that this part is an "Extremely Accurate I²C-Integrated RTC/TCXO/Crystal". And, hey, it does exactly what it says on the tin! This **Real Time Clock (RTC)** is the most precise you can get in a... 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