From Variscite Wiki
- Real Time Clock (RTC)

1 Setting the RTC

First set the system date & time:

# date --set="20171231 23:59"

Then set the HW RTC using the system date & time:

# hwclock --systohc --utc

Power down your board, wait 5 minutes and power up again, then check you system date & time and verify it is correct:

# date

2 Wake-up using the RTC

Wake-up using the RTC requires hardware connection of RTC IRQ pin to a SoC GPIO.
On DART-MX8M, DART-MX8M-MINI and DART-MX8M-PLUS carrier boards RTC IRQ pin is connected to GPIO1_15.
On VAR-SOM-MX8M-MINI, VAR-SOM-MX8M-NANO VAR-SOM-MX8M-PLUS carrier boards RTC IRQ pin is not connected.

2.1 Using rtcwake command

For example, to set the RTC to wakeup after 10 seconds type:

# echo enabled > /sys/class/rtc/rtc0/device/power/wakeup
# rtcwake -m mem -d rtc0 -s 10

For more options, like waking up at a specific time, run:

# rtcwake --help