Sysfs Interface
The sysfs interface can be used to read and set the status of RTC.
The interface only supports setting on the following two parameters:
- wakealarm: Run the following command to set a wakeup
alarm in X seconds since the current RTC time.
echo ‘+X’ > /sys/class/rtc/rtc0/wakealarm
Note: The interface is Linux original and the alarm is set in seconds. For example, to set an alarm which rings after 2 hours, use the following command:echo ‘+7200’ > /sys/class/rtc/rtc0/wakealarm
- offset: Used to calibrate the time offset caused by temperature and oscillator. Not recommended to use in the current product release.
The following code block shows a simple example.
# cd /sys/class/rtc/rtcO/
# ls
alarmtimer.0.auto hctosys range uevent
date max_user_freq since_epoch wakealarm
dev name subsystem
device offset time
# cat date
2001-02-01
# cat time
00:23:57