The Core-1684JD4 development board has the HYM8563 RTC (Real Time Clock) chip, which can keep the clock running through the button battery even when the development board is powered off.

The following are common RTC operations:

# View RTC time
$ sudo hwclock
2022-08-09 10:53:15.268874+0800

# View system time
Tue Aug 9 10:57:03 CST 2022

# Set system time to RTC time
$ sudo hwclock -s

# Save current system time to RTC
$ sudo hwclock -w