RTC update and operation in HL8548G


Does anybody know under which conditions the RTC is updated in the HL8548G?
Reading the AT command guide, I found these two:

  • Manually using AT+CCLK
  • From an NTP server using AT+KNTP

I wonder if either GPS or network time can be configured as time source. This said, I noticed that at least sometimes the AT+CCLK? returns the correct time although I never set it manually so there must be something.

Second question: Does the RTC continue to increment if VBAT is off and only BAT_RTC is maintained? Seems to be obvious but the spec is not clear on this and my tests seem to indicate that it is not.