Add accurate timekeeping to any project. The DS1307 Tiny RTC module keeps real time — seconds through to year, with automatic leap-year handling — over a simple I2C connection, and keeps ticking on its backup battery when main power is off. It also packs an onboard AT24C32 EEPROM (4 KB) for non-volatile storage, plus a programmable square-wave output. Works with Arduino, ESP32, Raspberry Pi, PIC and most microcontrollers. Backup battery not included.
- DS1307 real-time clock over I2C
- Onboard AT24C32 32 Kbit (4 KB) EEPROM
- Battery-backed — keeps time when powered off
- Programmable square-wave (SQ) output
- 32.768 kHz crystal for accurate timekeeping
- Works with Arduino, ESP32, Pi & PIC
- Footprint for an optional DS18B20 sensor
- 5V operation, I2C clock address 0x68
Specifications
What's in the box
Backup battery (LIR2032) not included — see the note below on battery type.
Great for
Getting started
- Wire it up
VCC→5V, GND→GND, SDA→SDA, SCL→SCL on your board.
- Fit a battery
Insert a charged LIR2032 (rechargeable) so it keeps time when the power is off.
- Add a library
Use an RTClib (DS1307) library in the Arduino IDE.
- Set the time
Run the set-time example once — it'll then keep time on its own.
Common questions
Is the battery included?
No. The module takes a rechargeable LIR2032 coin cell (not included). The board has a built-in charging circuit to keep it topped up while powered.
Can I use a normal CR2032 instead?
The Tiny RTC is designed for a rechargeable LIR2032 and will try to charge whatever is fitted. If you want to use a non-rechargeable CR2032, disable the onboard charging circuit first (remove the charging resistor/diode near the SQ pin) to avoid overcharging it. For most users a LIR2032 is the easy answer.
Does it work at 3.3V?
The I2C lines work fine at 3.3V, but the onboard battery charging needs 5V. Power the module from 5V for normal use.
What is the EEPROM for?
The onboard AT24C32 gives you 4 KB of non-volatile storage (I2C address 0x50) for settings, logs or calibration — completely separate from the clock.
Which library should I use?
Adafruit RTClib (or similar) with the DS1307 class. Set the time once via the example sketch and it keeps running on the backup battery.
Good to know: takes a rechargeable LIR2032 (not included) — not a throwaway CR2032 unless you disable the charger. Every order is checked before it ships from our Te Awamutu stock.