Chapter 9 Watch Timer; Functions Of Watch Timer - NEC 78K0/KD1 Series User Manual

9.1 Functions of Watch Timer

The watch timer has the following functions.
• Watch timer
• Interval timer
The watch timer and the interval timer can be used simultaneously.
Figure 9-1 shows the watch timer block diagram.
7
f /2
X
f
W
f
f
XT
Remark f : X1 input clock oscillation frequency
X
f : Subsystem clock oscillation frequency
XT
f : Watch timer clock frequency
W
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CHAPTER 9 WATCH TIMER

Figure 9-1. Watch Timer Block Diagram
Clear
11-bit prescaler
4 5 6 7 8 10
/2 f /2 f /2 f /2 f /2 f /2
W W W W W W
WTM7 WTM6
Preliminary User's Manual U16315EJ1V0UD
5-bit counter
11 9
f /2 f /2
W W
WTM5 WTM4 WTM3
Watch timer operation
mode register (WTM)
Internal bus
INTWT
Clear
INTWTI
WTM2 WTM1 WTM0