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RTC F207

Question asked by damh on Jun 28, 2013
Latest reply on Jun 28, 2013 by damh
MCU: STM32 F207 VG

We try to upgrade a device from STM32 F107 to F207.

We are glad to use the "old" RTC and to have a simple 32bit counter with a free settable prescaler (our RTC works at 1024Hz).

Now the "new" RTC is a BCD-coded version, normally working at 1Hz.

Is there a simple way, to:
- get it back into a simple counter (synchronize to LSE) and
- to work without VCC (power over VBAT only)?

To take a 32bit counter like TIM2 with external trigger over external pin connection from RTC calibration out seems to be a possibility but is there a smarter way?

The reference manual speaks about a possiblity to get the WUKF out to a pin (Output selection in RTC->CR to "Wakeup output enabled").

Have anyone verified this feature yet? What (unmentioned) precondition must be met to get it working?

Or is it a feature with notice "implemented but not wired"? ;-)

Thanks a lot!