Table 445. Swt_Sr Field Descriptions - STMicroelectronics SPC572L series Reference Manual

Software Watchdog Timer (SWT)
Field Name
Watchdog Service Code.This field is used to service the watchdog and to clear the soft lock bit
(SWT_CR[SLK]). If the SWT_CR[KEY] bit is set, two pseudorandom key values are written to
service the watchdog, see Section <Cross Refs>40.3.1.1 for details. Otherwise, the sequence
16-31 WSC
0xA602 followed by 0xB480 is written to the WSC field. To clear the soft lock bit (SWT_CR[SLK]),
the value 0xC520 followed by 0xD928 is written to the WSC field. When read, the WSC field always
returns zero.
40.3.1.6 SWT Counter Output Register (SWT_CO)
The SWT Counter Output (SWT_CO) register is a read-only register that shows the value of
the internal down counter when the SWT is disabled.
Offset
0x014
0 1 2 3 4 5 6 7 8 9
R
W
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Field Name
Watchdog Count. When the watchdog is disabled (SWT_CR[WEN]=0), this field shows the value
of the internal down counter. When the watchdog is enabled (SWT_CR[WEN]=1), this field is
cleared (the value is 0x0000_0000). Values in this field can lag behind the internal counter value
0-31 CNT
for up to six system plus eight counter clock cycles. Therefore, the value read from this field
immediately after disabling the watchdog may be higher than the actual value of the internal
counter.
40.3.1.7 SWT Service Key Register (SWT_SK)
The SWT Service Key (SWT_SK) register holds the previous (or initial) service key value.
This register is read-only if either the SWT_CR[HLK] or SWT_CR[SLK] bits are set.
Offset 0x018
0 1 2 3
R 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
W
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
856/2058

Table 445. SWT_SR field descriptions

1 1
0 1
Figure 389. SWT Counter Output Register (SWT_CO)
Table 446. SWT_CO field descriptions
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Figure 390. SWT Service Key Register (SWT_SK)
Description
1 1 1 1 1 1 1
2 3 4 5 6 7 8
CNT
Description
DocID027809 Rev 4
Access: Read-Only
1 2 2 2 2 2 2
24
9 0 1 2 3 5 6
Access: Read/Write
SK
RM0400
2 2 2 3 3
7 8 9 0 1