AT32F421
Series Reference Manual
2022.11.11
Page 301
Rev 2.02
TSF.
Note: The clearing operation of this bit takes effect after
two APB_CLK cycles.
Bit 10: 9
Reserved
0x0
resd
Kept at its default value.
Bit 8
ALAF
0x0
rw0c
Alarm clock A flag
0: No alarm clock event
1: Alarm clock event occurs
Note: The clearing operation of this bit takes effect after
two APB_CLK cycles.
Bit 7
IMEN
0x0
rw
Initialization mode enable
0: Initialization mode disabled
1: Initialization mode enabled
When an initialization mode is entered, the calendar stops
running.
Bit 6
IMF
0x0
ro
Enter initialization mode flag
0: Initialization mode is not entered
1: Initialization mode is entered
The ERTC_TIME, ERTC_DATE and ERTC_DIV registers
can be modified only when an initialization mode is
enabled (INITEN=1) and entered (INITEF=1).
Bit 5
UPDF
0x0
rw0c
Calendar update flag
0: Calendar update is in progress
1: Calendar update is complete
The UPDF bit is set each time the shadow register is
synchronized with the ERTC calendar value located in the
battery powered domain. The synchronization is
performed every two ERTC_CLK.
Bit 4
INITF
0x0
ro
Calendar initialization flag
0: Calendar has not been initialized
1: Calendar has been initialized
This bit is set when the calendar year filed (ERTC_DATE)
is different from 0. It is cleared when the year is 0.
Bit 3
TADJF
0x0
ro
Time adjustment flag
0: No time adjustment
1: Time adjustment is in progress
This bit is automatically set when a write access to the
ERTC_TADJ register is performed. It is automatically
cleared at the end of time adjustment.
Bit 2: 1
Reserved
0x0
resd
Kept at its default value.
Bit 0
ALAWF
0x1
ro
Alarm A register allows write flag
0: Alarm A register write operation not allowed
1: Alarm A register write operation allowed
17.4.5 ERTC divider register (ERTC_DIV)
Bit
Register
Reset value
Type
Description
Bit 31: 23 Reserved
0x000
resd
Kept at its default value.
Bit 22: 16 DIVA
0x7F
rw
Divider A
Bit 15
Reserved
0x0
resd
Kept at its default value.
Bit 14: 0
DIVB
0x00FF
rw
Divider B
Calendar clock = ERTC_CLK/((DIVA+1)x(DIVB+1))
17.4.6 ERTC alarm clock A register (ERTC_ ALA)
Bit
Register
Reset value
Type
Description
Bit 31
MASK4
0x0
rw
Date/week day mask
0: Date/week day is not masked
1: Alarm clock doesn’t care about date/week day
Bit 30
WKSEL
0x0
rw
Date/week day select
0: Date
1: Week day (DT[1: 0] is not used)
Bit 29: 28 DT
0x0
rw
Date tens
Bit 27: 24 DU
0x0
rw
Date/week day units
Bit 23
MASK3
0x0
rw
Hour mask