The STM32MP1 platform provides the internal real-time clock (RTC).
The internal RTC is enabled by default in the STM32MP1 BSP and does not require any additional configuration during Yocto build or run-time.
The BSP provides the standard Linux hwclock utility for fetching and updating the current time stored by the RTC.
When executed with the -w parameter, hwclock saves the current system time to the RTC:
root@stm32mp15-som:~# hwclock -w root@stm32mp15-som:~#
When executed without parameters or with the -r parameter, hwclock shows the saved current time:
root@stm32mp15-som:~# hwclock Tue Feb 27 02:39:07 UTC 2024
The RTC requires a CR-1220 battery installed in the BT1 connector to keep the current time during system power off state.