Adafruit
Adafruit PCF8523 Real Time Clock Breakout Board
Keep track of time even when your project loses power or gets reprogrammed. This updated PCF8523 Real Time Clock breakout features STEMMA QT / Qwiic connecto...
Keep track of time even when your project loses power or gets reprogrammed. This updated PCF8523 Real Time Clock breakout features STEMMA QT / Qwiic connectors for solderless I2C wiring, plus traditional breadboard headers. It works with both 3.3 V and 5 V power and logic, making it compatible with virtually any microcontroller or SBC.
Works with Arduino (using the Adafruit RTC library), CircuitPython, and Raspberry Pi or other single-board Linux computers. For higher precision (temperature-compensated), see the DS3231 Precision RTC. For DS1307 compatibility, see the DS1307 RTC Breakout.
Key Features
- PCF8523 RTC Chip – Battery-backed real-time clock with I2C interface
- STEMMA QT / Qwiic Connectors – Solderless I2C connection, compatible with SparkFun Qwiic
- 3.3 V and 5 V Compatible – Works with both power and logic levels
- CR1220 Battery Backup – Keeps time for 5+ years on a coin cell (battery not included)
- Breadboard Friendly – Header strip included for breadboard mounting
- Two Mounting Holes – For permanent installation
Compatibility
- Arduino (Adafruit RTClib library)
- CircuitPython / Python
- Raspberry Pi and other Linux SBCs
- Any microcontroller with I2C support
Ideal For
- Datalogging with accurate timestamps
- Clock and alarm projects
- Scheduled task execution
- STEMMA QT / Qwiic I2C projects
Package Contents
- 1× Adafruit PCF8523 Real Time Clock Breakout, fully assembled and tested
- 1× Header strip for breadboard mounting
Resources
- PCF8523 RTC Learn Guide – Code, libraries, schematics, and wiring diagrams
- What is STEMMA QT? – Introduction to the STEMMA QT connector system
Jargon buster
Plain-language definitions for the technical terms used above.
- breakout
- A breakout is a small circuit board that makes a tiny or hard-to-solder component easier to connect to with standard pins. It matters because this OLED module can be wired into a microcontroller project without needing to solder directly to the display’s fine contacts.
- CircuitPython
- A beginner-friendly version of Python designed to run directly on microcontroller boards. If a product supports CircuitPython, you can often program it by copying code files onto the board rather than setting up a more complex toolchain.
- Headers
- Rows of metal pins used to plug a module into a breadboard or connect it with jumper wires. Pre-soldered headers make the module easier to use straight away without needing to solder the pins yourself.
- I2C
- I2C is a two-wire communication bus used by many sensors and small modules. It matters because several I2C devices can share the same two wires, but each device needs a compatible address and your controller must support I2C.
- microcontroller
- A microcontroller is a small computer on a chip that runs your program and controls connected inputs and outputs. For this product, it is the part that reads buttons and sensors, drives the display and speaker, and communicates over Bluetooth.
- Qwiic
- Qwiic is a plug-in connector system for I2C devices that uses small 4-pin cables, so you can connect compatible sensors without soldering. It matters because your controller or adapter also needs Qwiic, or you will need a cable or breakout to wire it up.
- RTC
- A Real-Time Clock keeps track of time even when the main processor is asleep or powered down, usually with a small backup battery. It matters for data logging and tracking projects that need accurate timestamps.
- STEMMA
- A plug-and-cable connection system used on some maker electronics boards to make wiring simpler. If a product uses STEMMA, you need the matching cable or connector type to plug it in without soldering.
- STEMMA QT
- A small plug-in connector system for I2C boards that lets you connect compatible sensors and controllers without soldering. It matters because it can make wiring faster and less error-prone, especially when adding several small modules to a project.
Find this product in
Brands
Sensors & Input
Related Tutorials
Free guides on learn.littlebird.com.au
