Arduino Tiny RTC I2C Real Time Clock
This Arduino Tiny RTC I2C module incorporates the DS1307 I2C real time clock IC and the 24C32 32K I2C EEPROM storage. What's more, it has a DS18B20 temperature sensor on board. All of this in a tiny package of 25mm x 28mm x 8.4mm. It comes with a LIR2303 rechargeable lithium battery, and a charging circuit is included in the module. When the temperature sensor is off, the RTC module can run for 1 year on a sngle charge.
Specs of DS18B20 Temperature Sensor
- 3.0-5.5V input voltage
- -55°C to+125°C temperature range
- ±0.5°C accuracy from -10°C to +85°C
- 1 Wire interface
Wiring the RTC to Arduino
The most useful pins are duplicated from P1 to P2. The pin "BAT" can be fed into a ADC pin for monitoring the voltage of the battery. It is exposed for the convenience of measuring the voltage of the battery. The pinouts are explained below. Connecting "VCC" to 5 V will trickle charge the onboard battery.
Arduino Tiny RTC I2C Real Time Clock Pinout
|BAT||Battery voltage||To monitor the battery voltage, or not connected|
|VCC||5V supply||Power the module and charge the battery|
|SDA||I2C data||I2C data for the RTC|
|SCL||I2C clock||I2C clock for the RTC|
|DS||DS18B20 Temp. Sensor output||One wire inteface|
|SQ||Square wave output||Normally not used|
The I2C wires "SDA" and "SCL" are the data line and clock line, they should be connected to the corresponding pins depending on the Arduino board.
|Board||I2C / TWI pins|
|Uno, Ethernet||A4 (SDA), A5 (SCL)|
|Mega2560||20 (SDA), 21 (SCL)|
|Leonardo||2 (SDA), 3 (SCL)|
|Due||20 (SDA), 21 (SCL), SDA1, SCL1|
For more detail, please visit the Arduino Wire Library.
The schematics of this RTC module can be downloaded here.