UPD78F0890GK(A)-GAJ-AX NEC, UPD78F0890GK(A)-GAJ-AX Datasheet - Page 267

• Manufacturer Part Number: UPD78F0890GK(A)-GAJ-AX
• Description: 8BIT MCU, 128K FLASH, 7K RAM, LQFP
• Manufacturer: NEC

Specifications of UPD78F0890GK(A)-GAJ-AX

• Controller Family/series: UPD78F
• No. Of I/o's: 55
• Ram Memory Size: 7KB
• Cpu Speed: 20MHz
• No. Of Timers: 10
• No. Of Pwm: RoHS Compliant
• Core Size: 8bit
• Program Memory Size: 128KB
• Oscillator Type: External, Internal

10.3 Register Controlling Watch Timer
The watch timer is controlled by the watch timer operation mode register (WTM).
• Watch timer operation mode register (WTM)
Address: FF8FH
Symbol
WTM
This register sets the watch timer count clock, enables/disables operation, prescaler interval time, and 5-bit
counter operation control.
WTM is set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation clears WTM to 00H.
WTM7
WTM7
WTM6
WTM3
WTM1
WTM0
Figure 10-2. Format of Watch Timer Operation Mode Register (WTM)
7
0
1
0
0
0
0
1
1
1
1
0
0
1
1
0
1
0
1
After reset: 00H
f
f
Clear after operation stop
Start
Operation stop (clear both prescaler and 5-bit counter)
Operation enable
PRS
SUB
WTM6
WTM5
WTM2
/2
6
0
0
1
1
0
0
1
1
0
1
0
1
7
f
32.768 kHz
SUB
= 32.768 kHz
R/W
2
2
2
2
14
13
5
4
/f
/f
WTM5
WTM4
CHAPTER 10 WATCH TIMER
/f
/f
−
W
W
W
W
User’s Manual U17554EJ4V0UD
5
0
1
0
1
0
1
0
1
2
2
2
2
2
2
2
2
31.25 kHz
Watch timer count clock selection (f
f
4
5
6
7
8
9
10
11
PRS
/f
/f
/f
/f
/f
/f
WTM4
/f
/f
W
W
W
W
W
W
W
W
5-bit counter operation control
Watch timer operation enable
4
= 4 MHz
Interrupt time selection
WTM3
Prescaler interval time selection
62.5 kHz
f
3
PRS
= 8 MHz
WTM2
2
−
78.125 kHz
f
PRS
W
)
= 10 MHz
WTM1
<1>
156.25 kHz
f
PRS
= 20 MHz
WTM0
<0>
267