Suppose I use an oscillator instead of the suggested resonator for LSE. Will that even work, i.e., will the internal RTC continue to function when in battery mode? I assume that I'd have to power both oszillator and STM32 (using Vbat)?
Most probably yes. Don't forget that RCC_BDCR.LSEBYP has to be set. There are mixed reports on whether RCC_BDCR.LSERDY is usable for that case; but that's not fatal.
Most probably yes. Don't forget that RCC_BDCR.LSEBYP has to be set. There are mixed reports on whether RCC_BDCR.LSERDY is usable for that case; but that's not fatal.
