MPD789322 Datasheet, PDF (43/96 Pages) NEC – 8-BIT SINGLE-CHIP MICROCONTROLLER

µPD789322,789324,789326,789327
5.4.3 Watch timer control register
The following register controls the watch timer.
• Watch timer mode control register (WTM)
(1) Watch timer mode control register (WTM)
This register is used to enable/disable the count clock and operation of the watch timer and set the interval
time of the prescaler and operation control of the 5-bit counter.
WTM is set using a 1-bit or 8-bit memory manipulation instruction.
RESET input sets this register to 00H.
Figure 5-19. Format of Watch Timer Mode Control Register
Symbol
7
6
5
4
3
WTM WTM7 WTM6 WTM5 WTM4
0
2
<1>
<0> Address After reset R/W
0
WTM1 WTM0 FF4AH
00H
R/W
WTM7
0
fX/2⁷ (39.1 kHz)
1
fXT (32.768 kHz)
Watch timer count clock (fW) selection
WTM6 WTM5
0
0
0
0
0
1
0
1
1
0
1
0
Other than above
WTM4
0
1
0
1
0
1
2⁴/fW
2⁵/fW
2⁶/fW
2⁷/fW
2⁸/fW
2⁹/fW
Setting prohibited
Prescaler interval time selection
WTM1
0
Cleared after operation stopped
1
Start
5-bit counter operation control
WTM0
Watch timer operation enable
0
Operation stopped (both prescaler and timer cleared)
1
Operation enabled
Remarks 1. fW: Watch timer clock frequency (fX/2⁷ or fXT)
2. fX: Main system clock oscillation frequency
3. fXT: Subsystem clock oscillation frequency
4. The parenthesized values apply to operation at fX = 5.0 MHz or fXT = 32.768 kHz.
Preliminary Product Information U14673EJ1V0PM00
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