AT32F421
Series Reference Manual
2022.11.11
Page 291
Rev 2.02
Table 16-1 WDT timeout period (LICK=40kHz)
Prescaler divider
DIV[2: 0] bits
Min.timeout (ms)
RLD[11: 0] = 0x000
Max. timeout (ms)
RLD[11: 0] = 0xFFF
/4
0
0.1
409.6
/8
1
0.2
819.2
/16
2
0.4
1638.4
/32
3
0.8
3276.8
/64
4
1.6
6553.6
/128
5
3.2
13107.2
/256
(6 or 7)
6.4
26214.4
16.4 Debug mode
When the microcontroller enters debug mode (Cortex
TM
-M4 core halted), the WDT counter stops
counting by setting the WDT_PAUSE in the DEBUG module.
16.5 WDT registers
These peripheral registers must be accessed by words (32 bits).
Table 16-2 WDT register and reset value
Register name
Offset
Reset value
WDT_CMD
0x00
0x0000 0000
WDT_DIV
0x04
0x0000 0000
WDT_RLD
0x08
0x0000 0FFF
WDT_STS
0x0C
0x0000 0000
16.5.1 Command register (WDT_CMD)
(Reset in Standby mode)
Bit
Register
Reset value
Type
Description
Bit 31: 16 Reserved
0x0000
resd
Kept at its default value.
Bit 15: 0
CMD
0x0000
wo
Command register
0xAAAA: Reload counter
0x5555:
Unlock
write-protected WDT_DIV
and
WDT_RLD
0xCCCC: Enable WDT. If the hardware watchdog has
been enabled, ignore this operation.
16.5.2 Divider register (WDT_DIV)
Bit
Register
Reset value
Type
Description
Bit 31: 3
Reserved
0x0000 0000 resd
Kept at its default value.
Bit 2: 0
DIV
0x0
rw
Clock division value
000: LICK divided by 4
001: LICK divided by 8
010: LICK divided by 16
011: LICK divided by 32
100: LICK divided by 64
101: LICK divided by 128
110: LICK divided by 256
111: LICK divided by 256
The write protection must be unlocked in order to enable
write access to the register. The register can be read only
when DIVF=0.