PXS20RM Datasheet, PDF (1305/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

Software Watchdog Timer (SWT)
Offset 0x0000
Access: Read/Write
0
1
2
3
4
5
6
7
8
9
10 11 12
13
14 15
R MAP MAP MAP MAP MAP MAP MAP MAP 0 0 0 0 0 0 0 0
01234567
W
Reset 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0
16
17
18
19 20 21
22
23
24
25
26
27 28
29
30
31
R 0 0 0 0 0 0 KEY RIA WND ITR HLK SLK 1 STP FRZ WEN
W
Reset 0 0 0 0 0 0 0 1 0 0 0 1 1 0 1 0
Figure 45-1. SWT Control Register (SWT_CR)
Table 45-2. SWT_CR Field Descriptions
Field
Description
MAPn
KEY
RIA
WND
ITR
HLK
SLK
STP
Master Access Protection for Master n. The platform bus master assignments are device specific.
0 = Access for the master is not enabled
1 = Access for the master is enabled
Keyed Service Mode.
0 = Fixed Service Sequence, the fixed sequence 0xA602, 0xB480 is used to service the watchdog
1 = Keyed Service Mode, two pseudorandom key values are used to service the watchdog
Reset on Invalid Access.
0 = Invalid access to the SWT generates a bus error
1 = Invalid access to the SWT causes a system reset if WEN=1
Window Mode.
0 = Regular mode, service sequence can be done at any time
1 = Windowed mode, the service sequence is only valid when the down counter is less than the value in
the SWT_WN register.
Interrupt Then Reset.
0 = Generate a reset on a time-out
1 = Generate an interrupt on an initial time-out, reset on a second consecutive time-out
Hard Lock. This bit is only cleared at reset.
0 = SWT_CR, SWT_TO, SWT_WN and SWT_SK are read/write registers if SLK=0
1 = SWT_CR, SWT_TO, SWT_WN and SWT_SK are read only registers
Soft Lock. This bit is cleared by writing the unlock sequence to the service register.
0 = SWT_CR, SWT_TO SWT_WN and SWT_SK are read/write registers if HLK=0
1 = SWT_CR, SWT_TO, SWT_WN and SWT_SK are read only registers
Stop Mode Control. Allows the watchdog timer to be stopped when the device enters stop mode.
0 = SWT counter continues to run in stop mode
1 = SWT counter is stopped in stop mode
Freescale Semiconductor
PXS20 Microcontroller Reference Manual, Rev. 1
45-3