I need to put a unit into a low power mode (< 300uA), then be able to periodically wake it using either a 1Hz tick from the 32.768kHz crystal, or from a transition on any of the pins PC4 through PC7.
The system nominally runs at 16MHz using an HSE crystal with (no PLL).
It looks like I can attach PC4..7 to an EXTI line but I am unclear if EXTI needs to be processed by the NVIC.
I need to hold the latched state of several output pins when in the low power mode, although they won't be any significant current flow out of these pins.
I also need to hold the state of SRAM and the registers, so resuming code execution is possible.
Debug modes are not required.
It looks like CPU in Stop mode with regulator in Run is required to get current below 300uA. The issue seems to be if EXTI (from RC4..7, or RTC) can be configured to wake the system from this mode,
Pointers and comments appreciated, I am finding relevant ST documentation hard work at the moment.