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AT32F413
Series Reference Manual
2022.06.27
Page 264
Rev 2.00
18
Battery powered registers (BPR)
18.1 BPR introduction
The battery powered registers are located in the battery powered domain and powered by VDD/VBAT.
These registers are forty two 16-bit registers. Upon a tamper event or when battery powered domain
reset occurs, the contents in these registers are cleared so as to ensure the highest level of data security.
18.2 BPR main features
Forty two 16-bit registers
Reset at a tamper event
C
onfigurable PC13 pin multiplexed function output
18.3 BPR functional overview
To enable access to the battery powered registers, the PWCEN, BPREN and BPWEN must be set to 1.
The BPR provides tamper detection function for the purpose of data security. If enabled, the polarity of
the TAMPER pin can be configured through TPP bit. Once a tamper event is detected, the TPEF bit will
be set, and the battery powered registers will be cleared accordingly; If the tamper interrupt is enabled,
an interrupt will be generated, with the TPIF bit being set to 1.
In addition, the BPR also has RTC calibration feature so that the RTC clock can be slowed down up to
121 ppm by setting the CALVAL[6: 0] bits. If the RTC calibration output is enabled, the calibrated RTC/64
clock will be output on the TAMPER pin (CCOS=1).
Note: When TPP=0 or 1, if the TAMPER pin is already high or low before it is enabled by setting the
TPEN bit, an extra tamper event is generated when TPEN=1, despite the fact that there was no
rising or falling edge on the TAMPER pin.
18.4 BPR registers
These peripheral registers must be accessed by word (32 bits).
BPR registers are 16-bit addressable registers.
Table 18-1
BPR register map and reset values
Register
Offset
Reset value
BPR_DT1
0x04
0x0000
BPR_DT2
0x08
0x0000
BPR_DT3
0x0C
0x0000
BPR_DT4
0x10
0x0000
BPR_DT5
0x14
0x0000
BPR_DT6
0x18
0x0000
BPR_DT7
0x1C
0x0000
BPR_DT8
0x20
0x0000
BPR_DT9
0x24
0x0000
BPR_DT10
0x28
0x0000
BPR_RTCCAL
0x2C
0x0000
BPR_CTRL
0x30
0x0000
BPR_CTRLSTS
0x34
0x0000
BPR_DT11
0x40
0x0000
BPR_DT12
0x44
0x0000
BPR_DT13
0x48
0x0000