Adafruit
Adafruit PCF8523 Real Time Clock Assembled Breakout Board
Keep track of time even when your project loses power or gets reprogrammed. The PCF8523 Real Time Clock breakout is a battery-backed RTC that communicates ov...
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Keep track of time even when your project loses power or gets reprogrammed. The PCF8523 Real Time Clock breakout is a battery-backed RTC that communicates over I2C and works with both 3.3 V and 5 V power and logic. Perfect for datalogging, clock building, time stamping, timers, and alarms.
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
- 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 – PCB and header included, plugs straight into a breadboard
- 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
- Time-stamped sensor readings
Package Contents
- 1× Adafruit PCF8523 Real Time Clock Breakout, assembled with header
Resources
- PCF8523 RTC Learn Guide – Code, libraries, schematics, and wiring diagrams
Jargon buster
Plain-language definitions for the technical terms used above.
- breakout
- A breakout board carries a small or fine-pitched component and brings its connections out to standard, breadboard- and header-friendly pins. Describing a part as a breakout means it can be wired into a project without soldering directly to the component's tiny 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.
- 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 single chip that runs a stored program and controls connected inputs and outputs such as buttons, sensors, displays and communication interfaces. In a device built around one, it is the part that executes the code and coordinates the device's behaviour.
- PCB
- A printed circuit board (PCB) is a board, usually rigid, with etched copper tracks that connect electronic components together without loose wiring. Components are mounted on the board and signals route between them through the copper layout.
- 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.
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Sensors & Input
Related Tutorials
Free guides on learn.littlebird.com.au
