I have noticed an interesting fact that the system time (RTC), once set, is preserved after power off (complete removal of the power from the module)!
After power on (and before the time is set via network) the time is set to the last time before power off.
Is it the feature of the Unisoc 8910DM chipset used in those modules?
Where is the last time stored? If it is in the internal 8910DM flash it could lead to the wear of the used flash block after prolonged use.
It looks like it is the feature of the internal OS and I couldn’t find any reference to that feature.
Dear @loboris ,
Thank you for reaching out.
Yes, this is expected. The module can restore RTC from non-volatile (NV) storage after a complete power-off. This is controlled by AT+QCFG=“rtc/cfg” where NV enable decides whether to take the time saved by NV as the RTC initial value.
If you want to disable this behavior, set NV_enable=0 via AT+QCFG=“rtc/cfg”, and reboot; then the module will not initialize RTC from NV after power-on.
Best Regards,
Aghelan