Watch Timer Control Registers; Watch Timer Block Diagram - NEC PD78076 User Manual

11.3 Watch Timer Control Registers

The following two types of registers are used to control the watch timer.
• Timer clock select register 2 (TCL2)
• Watch timer mode control register (TMC2)
(1) Timer clock select register 2 (TCL2)
This register sets the watch timer count clock.
TCL2 is set with an 8-bit memory manipulation instruction.
RESET input sets TCL2 to 00H.
Remark Besides setting the watch timer count clock, TCL2 sets the watchdog timer count clock and buzzer
output frequency.
TMC21
7
f /2
XX
f
W
f
XT
f
W
4
2
TCL24
Timer Clock Select Register 2
CHAPTER 11 WATCH TIMER
Figure 11-1. Watch Timer Block Diagram
Clear
Prescaler
f f f f f
W W W W W
5 6 7 8 9
2 2 2 2 2
TMC26 TMC25 TMC24 TMC23 TMC22 TMC21 TMC20
Internal Bus
5-Bit Counter
Clear
3
Watch Timer Mode Control Register
f
W
14
2
INTWT
f
W
13
2
INTTM3
To 16-Bit
Timer/Event
Counter
271