How to setup un-used pins of STM32WLE5JCI6 for optimal EMC and current drain performance

[David_]

For best EMC immunity and minimum cell current (need months of cell life), how to setup un-used pins of STM32WLE5JCI6?  The chip in a module with metal screen box.  Pins are 'broken out' to edge of module with pcb trace of a few mm.

a. Should we program un-used pins as digital input (internal pull up, pull down or none), digital output (set to zero or one) or analogue input (seem minimum cell current drain as application note)?

b. Should un-used pin connect to Vdd, Ground or left open (if it is digital output)?

For EMC, the device should function properly near a cellular phone transmitting at maximum power (assume phone is far away from base station).  Phone is likely 4G or 5G (and 3G rarely).  Not sure if maximum transmit power differ?

Many thanks

[ASchw.1 · Accepted solution]

@David_ From my experience please do not define unused pins as inputs this can lead to excessive current consumption and EMC immunity will be reduced.
For Current consumption analog inputs is the best way to go (in most cases) while for EMC , digital output set to zero. Another option we used in some designs is digital input with PULL-DOWN.
I don't think that cellular phone transmissions are EMC challenging so you should not have too much trouble. 
Good Luck!