On 04/18/2016 03:18 PM, b2256 wrote:
Using Beaglebone Black(BBB)Rev C, Chronodot(ds3231) rtc via i2c, and
Ubuntu 14.04 armhf 4.4.0-armv7-x2 (Robert Nelson's armhf site).
I can get i2c recognition by BBB at 0x68 as expected with i2cdetect.
Registration seems to work using echo to new device on i2c-2, since it
comes up with a cat command. I can set hwclock and check with cat
/sys/class/rtc/rtc1 file and all seems fine, until I do a cold
reboot. Then everything reverts to Jan 15 01:01:00 2016. I am
booting from an SD disk instead of onboard.
With regard to rtc, a check on dmesg gives me a reversion back to the
rtc0 ,
"[ 3.748545] omap_rtc 44e3e000.rtc: rtc core: registered 44e3e000.rtc
as rtc0"
then
"[ 3.867388] PM: bootloader does not support rtc-only!"
[ 4.220591] omap_rtc 44e3e000.rtc: setting system clock to 2000-01-01
00:00:01 UTC (946684801)
Here you can see my manual entries:
[ 2481.604507] rtc-ds1307 2-0068: SET TIME!
[ 2481.608512] rtc-ds1307 2-0068: rtc core: registered ds3231 as rtc1
[ 2481.608866] i2c i2c-2: new_device: Instantiated device ds3231 at 0x68
My questions : Why or how does the rtc instance get written over
at boot?
Could this be a bootloader issue?
Is it a driver issue with Ubuntu non-support(states same as ds1307)?
I2c issue?
Or will the Chronodot simply not work with BBB and Ubuntu?
Note: Skill set- advanced newbie; not fresh newbie, but too hacking
dangerous to ever be an expert!
Thank you in advance for any insight that you may have.
B2256
I hit this sometime back with Debian moving to systemd. I haven't a
clue if Ubuntu images are using systemd or not. If so "unless changed"
systemd only supports rtc0. The answer I received from systemd mailing
list was set the clock from userspace not kernel space. I disagree, yet
pretty much got nowhere with that debate.
Really not an answer, maybe a bit of help...
Mike
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