![NXP Semiconductors MPC5605BK Скачать руководство пользователя страница 919](http://html.mh-extra.com/html/nxp-semiconductors/mpc5605bk/mpc5605bk_reference-manual_1721852919.webp)
Chapter 33 Software Watchdog Timer (SWT)
MPC5606BK Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor
919
33.5.2.7
SWT Service Key Register (SWT_SK)
The SWT Service Key (SWT_SK) register holds the previous (or initial) service key value. If either the
SWT_CR[HLK] or the SWT_CR[SLK] bit is set, this register is read-only.
Figure 7. SWT Service Register (SWT_SK)
Table 8. SWT_SK field descriptions
33.6
Functional description
The SWT is a 32-bit timer designed to enable the system to recover in situations such as software getting
trapped in a loop or if a bus transaction fails to terminate. It includes a a control register (SWT_CR), an
interrupt register (SWT_IR), time-out register (SWT_TO), a window register (SWT_WN), a service
register (SWT_SR), a counter output register (SWT_CO), and a service key register (SWT_SK).
The SWT_CR includes bits to enable the timer, set configuration options and lock configuration of the
module. The watchdog is enabled by setting the SWT_CR[WEN] bit. The reset value of the
SWT_CR[WEN] bit is device specific1 (enabled). This last bit is cleared when exiting ME RESET mode
in case flash user option bit 31 (WATCHDOG_EN) is 0. If the reset value of this bit is 1, the watchdog
starts operation automatically after reset is released. Some devices can be configured to clear this bit
automatically during the boot process.
The SWT_TO register holds the watchdog time-out period in clock cycles unless the value is less than
0x100, in which case the time-out period is set to 0x100. This time-out period is loaded into an internal
32-bit down counter when the SWT is enabled and each time a valid service sequence is written. The
Table 33-7. SWT_CO field descriptions
Field
Description
CNT
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, the value of this field is 0x0000_0000.
Values in this field can lag behind the internal counter value for as many as 6 system clock cycles
plus 8 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.
Address: Base + 0x0018
Access: User 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
SK
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
Description
SK
Service Key.This field is the previous (or initial) service key value used in keyed service mode. If
SWT_CR[KEY] is set, the next key value to be written to the SWT_SK is (17 × SK + 3) mod 2
16
.
Содержание MPC5605BK
Страница 2: ...This page is intentionally left blank...
Страница 20: ...MPC5606BK Microcontroller Reference Manual Rev 2 20 Freescale Semiconductor...
Страница 103: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 103 Clocks and power...
Страница 104: ...MPC5606BK Microcontroller Reference Manual Rev 2 104 Freescale Semiconductor This page is intentionally left blank...
Страница 243: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 243 Core platform modules...
Страница 244: ...MPC5606BK Microcontroller Reference Manual Rev 2 244 Freescale Semiconductor This page is intentionally left blank...
Страница 395: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 395 Communication modules...
Страница 396: ...MPC5606BK Microcontroller Reference Manual Rev 2 396 Freescale Semiconductor This page is intentionally left blank...
Страница 548: ...Chapter 24 LIN Controller LINFlexD MPC5606BK Microcontroller Reference Manual Rev 2 548 Freescale Semiconductor...
Страница 645: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 643 Timers...
Страница 646: ...MPC5606BK Microcontroller Reference Manual Rev 2 644 Freescale Semiconductor This page is intentionally left blank...
Страница 715: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 713 ADC system...
Страница 716: ...MPC5606BK Microcontroller Reference Manual Rev 2 714 Freescale Semiconductor This page is intentionally left blank...
Страница 787: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 787 Memory...
Страница 788: ...MPC5606BK Microcontroller Reference Manual Rev 2 788 Freescale Semiconductor This page is intentionally left blank...
Страница 893: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 893 Integrity...
Страница 894: ...MPC5606BK Microcontroller Reference Manual Rev 2 894 Freescale Semiconductor This page is intentionally left blank...
Страница 943: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 943 Debug...
Страница 944: ...MPC5606BK Microcontroller Reference Manual Rev 2 944 Freescale Semiconductor This page is intentionally left blank...