Difference between revisions of "RTC Cape"

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==Product Images==
 
==Product Images==
 
<gallery>
 
<gallery>
File:RTCCape650.jpg|Generic Proto Cape
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File:RTCCape650.jpg|RTC Cape
 
</gallery>
 
</gallery>
  

Revision as of 16:25, 13 December 2013

Descriptions

RTC Cape

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 Changes

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

  • Connect your BeagleBone Black to the internet, download the device tree files and extract them to /lib/firmware of your BBB:

cd /lib/firmware

wget http://elinux.org/images/e/e3/BBB-RTC-01-00A1.tar.gz

tar xzvf BBB-RTC-01-00A1.tar.gz


  • Load the device tree overlay for your RTC Cape:

echo BBB-RTC-01:00A1 > /sys/devices/bone_capemgr*/slots


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

dmesg | tail

[ 2016.295415] bone-capemgr bone_capemgr.8: slot #10: 'Override Board Name,00A1,Override Manuf,BBB-RTC-01'
[ 2016.295721] bone-capemgr bone_capemgr.8: slot #10: Requesting part number/version based 'BBB-RTC-01-00A1.dtbo
[ 2016.295777] bone-capemgr bone_capemgr.8: slot #10: Requesting firmware 'BBB-RTC-01-00A1.dtbo' for board-name 'Override Board Name', version '00A1'
[ 2016.296256] bone-capemgr bone_capemgr.8: slot #10: dtbo 'BBB-RTC-01-00A1.dtbo' loaded; converting to live tree
[ 2016.299751] bone-capemgr bone_capemgr.8: slot #10: #3 overlays
[ 2016.311744] omap_i2c 4802a000.i2c: bus 2 rev0.11 at 100 kHz
[ 2016.352020] rtc-ds1307 2-006f: rtc core: registered mcp7941x as rtc1
[ 2016.352091] rtc-ds1307 2-006f: 64 bytes nvram
[ 2016.352225] omap_i2c 4802a000.i2c: unable to select pin group
[ 2016.352428] bone-capemgr bone_capemgr.8: slot #10: Applied #3 overlays.


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

hwclock -r -f /dev/rtc1

Mon Jan 1 00:00:02 2001 0.000000 seconds


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

ntpdate -b -s -u pool.ntp.org

hwclock -w -f /dev/rtc1


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

hwclock -r -f /dev/rtc1

Fri Dec 13 22:51:56 2013 0.000000 seconds



Helpful Links



Specifications

Followings are some specifications of the RTC Cape:

Mechanical Specifications

Size 2.15" x 2.825"
Layers 2
PCB Thickness .062"
RoHS Compliant Yes



Signal Usage

RTC Cape
Power VDD_3V3EXP
I2C I2C1_SCL
I2C1_SDA
Multi-Function Pin GPIO1_29



Distributors

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



Product Images



Documentations

RTC Cape Revision A1

Coming soon.