The RTC Pi is a real time clock module which connects via the GPIO port on a Raspberry Pi.
Unlike other DS1307 based RTC modules the RTC Pi also includes a I2C logic level converter allowing you to connect other 5V I2C devices to your Raspberry Pi.
The RTC Pi is powered through the host Raspberry Pi using the GPIO port and extended pins on the GPIO connector allow you to stack the RTC Pi along with other expansion boards. The RTC Pi uses the DS1307 RTC real time clock and a CR2032 battery to maintain the date and time when the main system power is not available.
A mounting hole is provided so you can securely bolt the RTC Pi to your Raspberry Pi with our mounting kit (sold separately).
The RTC Pi can also be used on Arduino boards when connected via the I2C bus.
The i2c address for the DS1307 RTC is 0x68. This board is not compatible with the ADC Pi V1 board but is compatible with the Delta Sigma Pi and ADC Pi V2 when alternative i2c addresses are used.
Warning: Do not connect the RTC Pi to your Raspberry Pi when the power is connected without a CR2032 battery installed. This can cause damage to the DS1307 RTC chip.
The RTC Pi uses a CR2032 button battery (battery not included).
Due to shipping restrictions we are no longer allowed to ship the RTC Pi with a battery.
The RTC Pi is pin compatible with the the Raspberry Pi model B+ but the mounting hole will not be usable.
Click to download schematic PDF.
How to set and read the time
The RTC Pi requires a Linux kernel with i2c drivers such as the Occidentalis system image from http://learn.adafruit.com/adafruit-raspberry-pi-educational-linux-distro/overview which has i2c enabled.
To access the RTC Pi from your Raspberry Pi:
Boot the Pi from that image and execute these commands as root / su user:
First you need to register the DS1307 RTC chip with the I2C address of 0x68:
For Revision One boards use:
echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-0/new_device
For Revision Two boards use:
echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
To set the RTC Pi clock with the current system time:
View the current date and time stored in the RTC Pi:
Set the Linux system time to the value in the RTC Pi:
To set the RTC Pi with a custom time:
hwclock --set --date="2012-12-25 06:00:12" --utc
Battery Notes: We have had reports that some brands of button cells do not make a reliable connection when fully inserted into the battery holder on the version 1 RTC Pi boards. Moving the battery out by 3-5mm solves this problem.
The schematic for the RTC Pi version 1 can be found here.