CircuitCo:RTC Cape

Descriptions
The RTC Cape provides time tracking capability for the BeagleBone Black even when the power is lost. This cape features the MCP79410 I2C-based real-time clock/calendar and a holder for a coin battery type CR2032. Setup, reading, and setting up time is easy with the provided device tree overlay.

Revision A1
Initial release of RTC Cape.

Software Support & Compatibility

 * All revisions are compatible with BeagleBone and BeagleBone Black using 3.8 kernel.
 * Device tree files: BBB-RTC-01-00A1.tar.gz


 * Latest software for BeagleBone Black can be downloaded here.

Getting Started
The instructions below are performed on Angstrom release 2013.09.04 (Linux beaglebone 3.8.13 #1 SMP Wed Sep 4 09:09:32 CEST 2013 armv7l GNU/Linux).
 * Connect your BeagleBone Black to the internet, log in as root, download the device tree files and extract them to /lib/firmware of your BBB:


 * Load the device tree overlay for your RTC Cape:


 * Check to ensure the overlay is loaded. In the messages below, the MCP79410 is registered as rtc1:


 * Read the time from the RTC chip. It should look like something below since the time has not been set:


 * Update the system time of the BeagleBone Black (internet connection required) and write that to the RTC chip using hwclock command:


 * Read the time again. This time it should have been updated.

Helpful Links

 * MCP79410 datasheet
 * Capemgr wiki
 * Device Tree Usage
 * RTC on BeagleBone Black

Specifications
Followings are some specifications of the RTC Cape:

Distributors
Please visit Where To Buy for a list of distributors who carry BeagleBoardToys' capes.

RTC Cape Revision A1
Coming soon.