ubuntu@arm:~$ uname -a Linux arm 3.8.13-bone56 #1 SMP Thu Jun 5 03:28:17 UTC 2014 armv7l armv7l armv7l GNU/Linux ubuntu@arm:~$ sudo modprobe i2c-dev [sudo] password for ubuntu: ubuntu@arm:~$ sudo modprobe rtc-ds1307 ubuntu@arm:~$ sudo su root@arm:/home/ubuntu# echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device root@arm:/home/ubuntu# exit ubuntu@arm:~$ i2cdetect -r 1 WARNING! This program can confuse your I2C bus, cause data loss and worse! I will probe file /dev/i2c-1 using read byte commands. I will probe address range 0x03-0x77. Continue? [Y/n] y 0 1 2 3 4 5 6 7 8 9 a b c d e f 00: -- -- -- -- -- -- -- -- -- -- -- -- -- 10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 50: -- -- -- -- UU UU UU UU -- -- -- -- -- -- -- -- 60: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- -- 70: -- -- -- -- -- -- -- -- ubuntu@arm:~$ dmesg | grep -i rtc [ 0.000000] Kernel command line: console=tty0 console=ttyO0,115200n8 root=/dev/mmcblk0p2 ro rootfstype=ext4 rootwait fixrtc [ 2.040617] omap_rtc 44e3e000.rtc: rtc core: registered 44e3e000.rtc as rtc0 [ 2.048098] 44e3e000.rtc: already running [ 2.588181] [drm] Cannot find any crtc or sizes - going 1024x768 [ 2.755978] omap_rtc 44e3e000.rtc: setting system clock to 2015-03-02 20:22:07 UTC (1425327727) [ 316.024202] rtc-ds1307 1-0068: rtc core: registered ds1307 as rtc1 [ 316.024273] rtc-ds1307 1-0068: 56 bytes nvram [ 387.839058] rtc-ds1307 1-0068: read error -110 [ 395.037939] rtc-ds1307 1-0068: read error -121 [ 396.933940] rtc-ds1307 1-0068: read error -121 [ 399.159239] rtc-ds1307 1-0068: read error -121 [ 403.305763] rtc-ds1307 1-0068: read error -110 [ 405.666945] rtc-ds1307 1-0068: read error -121 [ 409.190567] rtc-ds1307 1-0068: read error -110 [ 413.414611] rtc-ds1307 1-0068: read error -121 [ 417.420955] rtc-ds1307 1-0068: read error -121 [ 419.338941] rtc-ds1307 1-0068: read error -110 [ 420.348677] rtc-ds1307 1-0068: read error -110 [ 421.360407] rtc-ds1307 1-0068: read error -110 [ 423.727597] rtc-ds1307 1-0068: read error -110 [ 424.737348] rtc-ds1307 1-0068: read error -110 [ 425.749073] rtc-ds1307 1-0068: read error -110 [ 427.901427] rtc-ds1307 1-0068: read error -110 [ 428.911174] rtc-ds1307 1-0068: read error -110 [ 429.920948] rtc-ds1307 1-0068: read error -110 [ 434.700249] rtc-ds1307 1-0068: read error -121 [ 436.917053] rtc-ds1307 1-0068: read error -110 [ 437.926803] rtc-ds1307 1-0068: read error -110 [ 438.938526] rtc-ds1307 1-0068: read error -110 [ 441.061720] rtc-ds1307 1-0068: read error -110 [ 442.224880] rtc-ds1307 1-0068: read error -121 [ 444.278373] rtc-ds1307 1-0068: read error -121 [ 446.477598] rtc-ds1307 1-0068: read error -110 [ 447.487349] rtc-ds1307 1-0068: read error -110 [ 448.499073] rtc-ds1307 1-0068: read error -110 [ 450.598693] rtc-ds1307 1-0068: read error -110 [ 451.608440] rtc-ds1307 1-0068: read error -110 [ 452.618217] rtc-ds1307 1-0068: read error -110 [ 454.743228] rtc-ds1307 1-0068: read error -110 [ 455.752966] rtc-ds1307 1-0068: read error -110 [ 456.762750] rtc-ds1307 1-0068: read error -110 [ 458.991271] rtc-ds1307 1-0068: read error -110 [ 460.001021] rtc-ds1307 1-0068: read error -110 [ 461.012747] rtc-ds1307 1-0068: read error -110 [ 462.208031] rtc-ds1307 1-0068: read error -121 [ 469.135334] rtc-ds1307 1-0068: read error -121 [ 470.247947] rtc-ds1307 1-0068: read error -5 ubuntu@arm:~$ sudo hwclock -f /dev/rtc1 -r --debug hwclock from util-linux 2.20.1 Using /dev interface to clock. Last drift adjustment done at 1435111408 seconds after 1969 Last calibration done at 1435111408 seconds after 1969 Hardware clock is on UTC time Assuming hardware clock is kept in UTC time. Waiting for clock tick... /dev/rtc1 does not have interrupt functions. Waiting in loop for time from /dev/rtc1 to change hwclock: ioctl(RTC_RD_TIME) to /dev/rtc1 to read the time failed: Invalid argument ...synchronization failed ubuntu@arm:~$ sudo hwclock -f /dev/rtc1 -r --debug hwclock from util-linux 2.20.1 Using /dev interface to clock. Last drift adjustment done at 1435111408 seconds after 1969 Last calibration done at 1435111408 seconds after 1969 Hardware clock is on UTC time Assuming hardware clock is kept in UTC time. Waiting for clock tick... /dev/rtc1 does not have interrupt functions. Waiting in loop for time from /dev/rtc1 to change hwclock: ioctl(RTC_RD_TIME) to /dev/rtc1 to read the time failed: Input/output error ...synchronization failed ubuntu@arm:~$ sudo hwclock -f /dev/rtc1 -r --debug hwclock from util-linux 2.20.1 Using /dev interface to clock. Last drift adjustment done at 1435111408 seconds after 1969 Last calibration done at 1435111408 seconds after 1969 Hardware clock is on UTC time Assuming hardware clock is kept in UTC time. Waiting for clock tick... /dev/rtc1 does not have interrupt functions. Waiting in loop for time from /dev/rtc1 to change ...got clock tick Time read from Hardware Clock: 2015/06/25 01:50:08 Hw clock time : 2015/06/25 01:50:08 = 1435197008 seconds since 1969 Thu 25 Jun 2015 01:50:08 AM UTC -0.041532 seconds ubuntu@arm:~$ ubuntu@arm:~$ lsmod Module Size Used by g_multi 51145 0 libcomposite 14931 1 g_multi 8192cu 455416 0