CHAPTER 9 WATCH TIMER FUNCTION
User’s Manual U15109EJ3V0UD
311
9.3 Watch Timer Control Register
The watch timer mode control register (WTNM), watch timer high-speed clock select register (WTNHC), and watch
timer clock select register (WTNCS) control the watch timer. The watch timer should be operated after setting the
count clock and interval time.
(1) Watch timer mode control register (WTNM)
This register enables or disables the count clock and operation of the watch timer, sets the interval time of the
prescaler, controls the operation of the 5-bit counter, and sets the interrupt time of the watch timer.
WTNM is set by an 8-bit or 1-bit memory manipulation instruction.
RESET input clears WTNM to 00H.
After reset: 00H
R/W
Address: FFFFF360H
7
6
5
4
3
2
<1>
<0>
WTNM
WTNM7
WTNM6
WTNM5
WTNM4
WTNM3
WTNM2
WTNM1
WTNM0
WTNM6
WTNM5
WTNM4
Selects interval time of prescaler
0
0
0
2
4
/f
W
(488
µ
s)
0
0
1
2
5
/f
W
(977
µ
s)
0
1
0
2
6
/f
W
(1.95 ms)
0
1
1
2
7
/f
W
(3.91 ms)
1
0
0
2
8
/f
W
(7.81 ms)
1
0
1
2
9
/f
W
(15.6 ms)
1
1
0
2
10
/f
W
(31.2 ms)
1
1
1
2
11
/f
W
(62.4 ms)
WTNM3
WTNM2
Selects interrupt time of watch timer
0
0
2
14
/f
W
(0.5 s)
0
1
2
13
/f
W
(0.25 s)
1
0
2
5
/f
W
(977
µ
s)
1
1
2
4
/f
W
(488
µ
s)
WTM1
Controls operation of 5-bit counter
0
Clears after operation stops
1
Starts
WTNM0
Enables operation of watch timer
0
Stops operation (clears both prescaler and 5-bit counter)
1
Enables operation
Remarks 1.
f
W
: Watch timer clock frequency
2.
Values in parentheses apply when f
W
= 32.768 kHz.
3.
For the settings of WTNM7, refer to
9.3 (3) Watch timer clock select register
(WTNCS)
.
