Chapter 10 Watch Timer; Functions Of Watch Timer - NEC 78K0 Series User Manual

10.1 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 10-1 shows the watch timer block diagram.
7
f /2
PRS
f
W
f
f
W
SUB
Remark f : Peripheral hardware clock frequency
PRS
f : Subsystem clock frequency
SUB
f : Watch timer clock frequency (f
W
f : f or f
WX W

CHAPTER 10 WATCH TIMER

Figure 10-1. Block Diagram of Watch Timer
Clear
11-bit prescaler
4 5 6 7 8 10
/2 f /2 f /2 f /2 f /2 f /2 f
W W W W W
WTM7 WTM6
PRS
9
/2
W
Preliminary User's Manual U17260EJ3V1UD
f
WX
5-bit counter
11 9
/2 f /2
W W
WTM5 WTM4 WTM3
Watch timer operation
mode register (WTM)
Internal bus
7
/2 or f )
SUB
4
f /2
WX
5
f /2
WX
Clear
WTM2 WTM1 WTM0
INTWT
INTWTI
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