Watchdog Timer Control Registers - NEC UPD789026 Series User Manual

8.3 Watchdog Timer Control Registers

The following two types of registers are used to control the watchdog timer.
• Timer clock select register 2 (TCL2)
• Watchdog timer mode register (WDTM)
(1) Timer clock select register 2 (TCL2)
This register sets the watchdog timer count clock.
TCL2 is set with an 8-bit memory manipulation instruction.
RESET input clears TCL2 to 00H.
Symbol
TCL2
TCL22
Remarks 1. f
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Figure 8-2. Timer Clock Select Register 2 Format
7 6 5
0 0 0
TCL21 TCL20
Watchdog Timer Count Clock Selection
0 0 0 f /2
X
0 1 0 f /2
X
1 0 0 f /2
X
1 1 0 f /2
X
Other than above Setting prohibited
: System clock oscillation frequency
X
2. The parenthesized values apply to operation at f
CHAPTER 8 WATCHDOG TIMER
4 3 2
0 0 TCL22 TCL21
4
(312.5 kHz)
6
(78.1 kHz)
8
(19.5 kHz)
10
(4.88 kHz)
User's Manual U11919EJ3V0UM00
1 0
Address
TCL20 FF42H
Interval Time
µ
11
2 /f (410 s)
X
13
2 /f (1.64 ms)
X
15
2 /f (6.55 ms)
X
17
2 /f (26.2 ms)
X
= 5.0 MHz.
X
After Reset R/W
00H R/W
117