4.9 Backup I/O Pins

These pins can be used when operating in Backup mode and are not mapped to the normal PORT functions, hence these pins are controlled by the related peripheral registers.

Table 4-34. Backup I/O Pins
PeripheralSignalI/O Pin
XOSC32KXIN32PA00
XOSC32KXOUT32PA01
RTCIN0PB00
SUPC (or RTC)OUT0 (or OUT)PB01
SUPC (or RTC)OUT1 (or IN1)PB02
SUPCVBATPB03
RTCIN3PC00
RTCIN4PC01
Important: These I/Os have specific electrical characteristics. Refer to I/O Pin Electrical Specifications.