CHAPTER 10 WATCH TIMER
Preliminary User’s Manual U17260EJ3V1UD
289
10.3 Register Controlling Watch Timer
The watch timer is controlled by the watch timer operation mode register (WTM).
•
Watch timer operation mode register (WTM)
This register sets the watch timer count clock, enables/disables operation, prescaler interval time, and 5-bit
counter operation control.
WTM is set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation sets WTM to 00H.
Figure 10-2. 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
Watch timer count clock selection (f
W
)
WTM7
f
SUB
= 32.768 kHz
f
PRS
= 2 MHz
f
PRS
= 5 MHz
f
PRS
= 10 MHz
f
PRS
= 20 MHz
0
f
PRS
/2
7
−
15.625 kHz
39.062 kHz
78.125 kHz
156.25 kHz
1
f
SUB
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
Selection of watch timer interrupt time
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 5-bit counter)
1
Operation
enable