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Software Watchdog Timer (SWT)
MPC5644A Microcontroller Reference Manual, Rev. 6
618
Freescale Semiconductor
Figure 20-5. SWT Service Register (SWT_SR)
20.3.2.6
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.
Figure 20-6. SWT Counter Output Register (SWT_CO)
20.3.2.7
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_MCR[HLK] or SWT_MCR[SLK] bits are set.
Offset 0x010
Access: Read/Write
0
1
2
3
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
R 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
W
WSC
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
Table 20-6. SWT_SR field description
Field
Description
WSC
Watchdog Service Code
This field is used to service the watchdog and to clear the soft lock bit (SWT_MCR[SLK]). If the
SWT_MCR[KEY] bit is set, two pseudorandom key values are written to service the watchdog, see
Section 20.4, Functional description
, for details. Otherwise, the sequence 0xA602 followed by 0xB480 is
written to the WSC field. To clear the soft lock bit (SWT_MCR[SLK]), the value 0xC520 followed by 0xD928
is written to the WSC field.
Offset 0x014
Access: Read-only
0
1
2
3
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
R
CNT
W
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 1
1
1 0 1 0 0 0 1
Table 20-7. SWT_CO Register field description
Field
Description
CNT
Watchdog Count
When the watchdog is disabled (SWT_MCR[WEN] = 0) this field shows the value of the internal down
counter. When the watchdog is enabled the value of this field is 0x0000_0000. Values in this field can lag
behind the internal counter value 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.
Summary of Contents for MPC5644A
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Page 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Page 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
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