
Freescale Semiconductor
27-1
Chapter 27
Watchdog Timer Module
27.1
Introduction
The watchdog timer (WDT) is a 16-bit timer used to help software recover from runaway code. The
watchdog timer has a free-running down-counter (watchdog counter) that generates a reset on underflow.
To prevent a reset, software must periodically restart the countdown by servicing the watchdog.
27.1.1
Low-Power Mode Operation
This subsection describes the operation of the watchdog module in low-power modes and halted mode of
operation (by issuing a HALT instruction). Low-power modes are described in
shows the watchdog module operation in the low-power modes, and shows how
this module may facilitate exit from each mode.
In wait mode, with the watchdog control register’s WAIT bit (WCR[WAIT]) set, watchdog timer operation
stops. In wait mode with the WCR[WAIT] bit cleared, the watchdog timer continues to operate normally.
In doze mode with the WCR[DOZE] bit set, the watchdog timer module operation stops. In doze mode
with the WCR[DOZE] bit cleared, the watchdog timer continues to operate normally. Watchdog timer
operation stops in stop mode. When stop mode is exited, the watchdog timer continues to operate in its
pre-stop mode state.
In halted mode (entered by issuing a HALT instruction or asserting BKPT) with the WCR[HALTED] bit
set, watchdog timer module operation stops. When halted mode is exited, watchdog timer operation
continues from the state it was in before entering halted mode, but any updates made in halted mode
remain. If the WCR[HALTED] bit is cleared, the watchdog timer continues to operate normally after
executing a HALT instruction. This is a debug feature available for the user
Table 27-1. Watchdog Module Operation in Low-power Modes
Low-power Mode
Watchdog Operation
Mode Exit
Wait
Normal if WCR[WAIT] cleared, stopped otherwise
Upon Watchdog reset
Doze
Normal if WCR[DOZE] cleared, stopped otherwise
Upon Watchdog reset
Stop
Stopped
No, only via external interrupts
MCF5329 Reference Manual, Rev 3
Содержание MCF5329
Страница 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 126: ...Enhanced Multiply Accumulate Unit EMAC 4 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 564: ...Liquid Crystal Display Controller LCDC 22 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 692: ...Programmable Interrupt Timers PIT0 PIT3 28 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 720: ...Queued Serial Peripheral Interface QSPI 30 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 790: ...Message Digest Hardware Accelerator MDHA 33 20 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Страница 902: ...Register Memory Map Quick Reference A 26 Freescale Semiconductor MCF5329 Reference Manual Rev 3...