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The Adafruit DS1307 Real Time Clock breakout keeps accurate time even when your microcontroller loses power or is reprogrammed. This battery-backed I2C RTC i...

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The Adafruit DS1307 Real Time Clock breakout keeps accurate time even when your microcontroller loses power or is reprogrammed. This battery-backed I2C RTC is one of the most widely used clock chips, making it a reliable choice for datalogging, alarms, timers, and clock projects.

The DS1307 requires 5V power but has been successfully used with 3.3V logic levels. It comes fully assembled with headers, ready to plug into a breadboard. A CR1220 coin cell battery (not included) provides backup power for 5+ years of timekeeping.

Key Features

  • Battery-Backed Timekeeping – Maintains time through power loss and reprogramming
  • I2C Interface – Simple two-wire communication
  • 5+ Year Battery Life – With CR1220 coin cell (not included)
  • Fully AssembledPCB and headers included, breadboard-ready
  • Two Mounting Holes – For permanent installations

Also Available

Ideal For

  • Datalogging with timestamps
  • Clock and alarm projects
  • Scheduled automation and timers
  • Any project needing persistent timekeeping

Package Contents

  • 1× DS1307 RTC breakout board (fully assembled with headers)
Note: CR1220 coin cell battery not included. The DS1307 requires 5V power. It may lose or gain up to 2 seconds per day — for higher precision, consider the DS3231.

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.
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.
PCB
A printed circuit board is a rigid board with copper tracks that connect electronic parts without loose wires. For this kit, the PCBs also form the airplane shape, so they are both the circuit base and part of the finished model.
ppm
ppm means parts per million, a common way to express very small gas concentrations in air. For CO₂ sensors, the ppm range tells you what levels the sensor can measure, such as normal indoor air through to poorly ventilated spaces.
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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