@Lundin I'd guess that cadence is an umbrella tag for anything that Cadence Design Systems makes. They make Virtuoso (an IC design software). They make Allegro (a PCB design software on a tier above OrCAD and Altium).
@JohnRennie By the way, you called it a MOSFET. The example doesn't mention "MOSFET", and the symbol looks like a JFET. Are you sure that it's a MOSFET and not a JFET ?
Oops, that was not a deliberate action. It's just a FET. My nephew has asked me this on the grounds I'm a physicist and should know such things. Sadly no physics course I ever did covered FETs.
The STM32 RTC locks (freezes) the RTC when you read the time register and un-freezes it when you read the date register. This is done to protect you from the situation where you read the time just before midnight (e.g. 23:59:59) and then the RTC date rolls over to the next day before you read it...