AT32F421
Series Reference Manual
2022.11.11
Page 302
Rev 2.02
0: No hour mask
1: Alarm clock doesn’t care about hours
Bit 22
AMPM
0x0
rw
AM/PM
0: AM
1: PM
Note: This bit is applicable for 12-hour format only. It is 0
for 24-hour format.
Bit 21: 20 HT
0x0
rw
Hour tens
Bit 19: 16 HU
0x0
rw
Hour units
Bit 15
MASK2
0x0
rw
Minute mask
0: No minute mask
1: Alarm clock doesn’t care about minutes
Bit 14: 12 MT
0x0
rw
Minute tens
Bit 11: 8
MU
0x0
rw
Minute units
Bit 7
MASK1
0x0
rw
Second mask
0: No second mask
1: Alarm clock doesn’t care about seconds
Bit 6: 4
ST
0x0
rw
Second tens
Bit 3: 0
SU
0x0
rw
Second units
17.4.7 ERTC write protection register (ERTC_WP)
Bit
Register
Reset value
Type
Description
Bit 31: 8 Reserved
0x000000
resd
Kept at its default value
Bit 7: 0
CMD
0x00
wo
Command register
All ERTC register write protection is unlocked by writing
0xCA and 0x53. Writing any other value will re-activate
write protection.
17.4.8 ERTC subsecond register (ERTC_SBS)
Bit
Register
Reset value
Type
Description
Bit 31: 16 Reserved
0x0000
resd
Kept at its default value
Bit 15: 0 SBS
0x0000
ro
Sub-second value
Subsecond is the value in the DIVB counter. Clock
frequency = ERTC_CLK/(DIVA+1)
17.4.9 ERTC time adjustment register (ERTC_TADJ)
Bit
Register
Reset value
Type
Description
Bit 31
ADD1S
0x0
wo
Add 1 second
0: No effect
1: Add one second
This bit can be written only when TADJF=0. It is intended
to be used with DECSBS in order to fine-tune the time.
Bit 30: 15 Reserved
0x0000
resd
Kept at its default value
Bit 14: 0 DECSBS
0x0000
wo
DECSBS[14: 0]: Decrease sub-second value
Delay (ADD1S=0): Delay = DECSBS/(DIVB+1)
Advance (ADD1S=1) : Advance =1-(DECSBS/(DIVB+1))
17.4.10 ERTC time stamp time register (ERTC_TSTM)
Bit
Register
Reset value
Type
Description
Bit 31: 23 Reserved
0x000
resd
Kept at its default value
Bit 22
AMPM
0x0
ro
AM/PM
0: AM
1: PM
Note: This bit is applicable for 12-hour format only. It is 0
for 24-hour format.
Bit 21: 20 HT
0x0
ro
Hour tens
Bit 19: 16 HU
0x0
ro
Hour units