ST STM32L4+ Series Reference Manual page 1646

Tamper and backup registers (TAMP) applied to STM32L4P5xx and STM32L4Q5xx only
Bits 31:0 BKP[31:0]
1646/2301
The application can write or read data to and from these registers.
They are powered-on by V
reset, and their contents remain valid when the device operates in low-power mode.
In the default configuration this register is reset on a tamper detection event. It is forced to
reset value as long as there is at least one external tamper flag being set. This register is
also reset when the readout protection (RDP) is disabled.
when V is switched off, so that they are not reset by System
BAT DD
RM0432 Rev 6
RM0432