CHAPTER 8 WATCH TIMER
User’s Manual U13850EJ4V0UM
231
(1) Watch timer
The watch timer generates an interrupt request (INTWTN) at time intervals of 0.5 seconds or 0.25 seconds by
using the main system clock or subsystem clock.
(2) Interval timer
The watch timer generates an interrupt request (INTWTNI) at time intervals specified in advance.
Table 8-1. Interval Time of Interval Timer
Interval Time
f
XT
= 32.768 kHz
2
4
×
1/f
W
488
µ
s
2
5
×
1/f
W
977
µ
s
2
6
×
1/f
W
1.95 ms
2
7
×
1/f
W
3.91 ms
2
8
×
1/f
W
7.81 ms
2
9
×
1/f
W
15.6 ms
2
10
×
1/f
W
31.2 ms
2
11
×
1/f
W
62.4 ms
Remark
f
W
: Watch timer clock frequency
8.2 Configuration
The watch timer includes the following hardware.
Table 8-2. Configuration of Watch Timer
Item
Configuration
Counter
5 bits
×
1
Prescaler
11 bits
×
1
Control registers
Watch timer mode control register (WTNM)
Watch timer clock selection register (WTNCS)