CHAPTER 9 WATCH TIMER
Preliminary User’s Manual U16315EJ1V0UD
205
Figure 9-2. Format of Watch Timer Operation Mode Register (WTM)
Address: FF6FH After reset: 00H R/W
Symbol
7
6
5
4
3
2
1
0
WTM
WTM7
WTM6
WTM5
WTM4
WTM3
WTM2
WTM1
WTM0
WTM7
Watch timer count clock selection
0
f
X
/2
7
(78.125 kHz)
1
f
XT
(32.768 kHz)
WTM6
WTM5
WTM4
Prescaler interval time selection
0
0
0
2
4
/f
W
0
0
1
2
5
/f
W
0
1
0
2
6
/f
W
0
1
1
2
7
/f
W
1
0
0
2
8
/f
W
1
0
1
2
9
/f
W
1
1
0
2
10
/f
W
1
1
1
2
11
/f
W
WTM3
WTM2
Interrupt time selection
0
0
2
14
/f
W
0
1
2
13
/f
W
1
0
2
5
/f
W
1
1
2
4
/f
W
WTM1
5-bit counter operation control
0
Clear after operation stop
1
Start
WTM0
Watch timer operation enable
0
Operation stop (clear both prescaler and timer)
1
Operation enable
Caution
Do not change the count clock and interval time (by setting bits 4 to 7 (WTM4 to WTM7) of WTM)
during watch timer operation.
Remarks 1.
f
W
: Watch timer clock frequency (f
X
/2
7
or f
XT
)
2.
f
X
: X1 input clock oscillation frequency
3.
f
XT
: Subsystem clock oscillation frequency
4.
Figures in parentheses apply to operation with f
X
= 10 MHz, f
XT
= 32.768 kHz.