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CMS80F731x Reference Manual
13.3 Feature Description
The internal wake-up timer works on the principle that after the system enters sleep mode, the CPU stops working with all
peripheral circuitry, and the internal low-power oscillator LSI begins to operate, and its oscillation clock is 125KHz (T
LSI
≈ 8us).
Provides a clock for the WUT counter.
There are two internal wake-up timer registers: WUTCRH and WUTRCL.
Bit7 of the WUTCRH register is an internal timed wake-up enable bit:
-
WUTEN=1: Turn on the timed wake-up function;
-
WUTEN=0: Turns off timed wake-up.
{WUTCRH[3:0] and WUTCRL[7:0]} form a 12-bit timed wake-up data register, after entering sleep mode, the HUT counter
starts to time, when the value of the WUT counter is equal to the value of the timed wake-up data register, start the system
oscillator, enter the wake-up waiting state.
Timed wake-up time:T=(WUTD
[
11:0
]
+1)×WUTPS×T
LS
I
