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Functional Description
1800
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Watchdog Timers
28.3.1 Register Access Timing
Because the WDT1 module has an independent clocking domain, its registers must be written with a
timing gap between accesses. Software must guarantee that this delay is inserted between back-to-back
writes to WDT1 registers or between a write followed by a read to the registers. The timing for back-to-
back reads from the WDT1 module has no restrictions. The WRC bit in the Watchdog Control (WDTCTL)
register for WDT1 indicates that the required timing gap has elapsed. This bit is cleared on a write
operation and set when the write completes, indicating to software that another write or read may be
started safely. Software should poll WDTCTL for WRC = 1 prior to accessing another register. Note that
WDT0 does not have this restriction as it runs off the system clock.
28.4 Initialization and Configuration
To use the WDT, its peripheral clock must be enabled by setting the Rn bit in the Watchdog Timer Run
Mode Clock Gating Control (RCGCWD) register, see
The Watchdog Timer is configured using the following sequence:
1. Load the WDTLOAD register with the desired timer load value.
2. If WDT1, wait for the WRC bit in the WDTCTL register to be set.
3. Set the INTEN bit (if interrupts are required) or the RESEN bit (if a reset is required after two timeouts)
in the WDTCTL register. The Watchdog Timer starts when either of them is enabled.
If software requires that all of the watchdog registers are locked, the Watchdog Timer module can be fully
locked by writing any value to the WDTLOCK register. To unlock the Watchdog Timer, write a value of
0x1ACC.E551.
To service the watchdog, periodically reload the count value into the WDTLOAD register to restart the
count. The interrupt can be enabled using the INTEN bit in the WDTCTL register to allow the processor to
attempt corrective action if the watchdog is not serviced often enough. The RESEN bit in WDTCTL can be
set so that the system resets if the failure is not recoverable using the ISR.
NOTE:
The application should be sure not to modify the ALTCLK encoding in the ALTCLKCFG
register while WDT1 is enabled and running.