UPD78F9222MC(T)-5A4-A NEC, UPD78F9222MC(T)-5A4-A Datasheet - Page 150

• Manufacturer Part Number: UPD78F9222MC(T)-5A4-A
• Description: 8BIT MCU, 4K FLASH, 256B RAM, 78F9222
• Manufacturer: NEC

Specifications of UPD78F9222MC(T)-5A4-A

• Controller Family/series: UPD78
• No. Of I/o's: 17
• Ram Memory Size: 256Byte
• Cpu Speed: 10MHz
• No. Of Timers: 4
• No. Of: RoHS Compliant
• Core Size: 8bit
• Program Memory Size: 4KB
• Oscillator Type: External, Internal

9.3
(1) Watchdog timer mode register (WDTM)
150
Address: FF48H
The watchdog timer is controlled by the following two registers.
• Watchdog timer mode register (WDTM)
• Watchdog timer enable register (WDTE)
Symbol
WDTM
This register sets the overflow time and operation clock of the watchdog timer.
This register can be set by an 8-bit memory manipulation instruction and can be read many times, but can be
written only once after reset is released.
Reset signal generation sets this register to 67H.
Registers Controlling Watchdog Timer
Notes 1.
WDCS4
WDCS2
0
0
1
0
0
0
0
1
1
1
1
7
0
2.
Note 1
Note 2
After reset: 67H
WDCS3
WDCS1
If “low-speed internal oscillator cannot be stopped” is specified by the option byte, this cannot
be set. The low-speed internal oscillation clock will be selected no matter what value is
written.
Reset is released at the maximum cycle (WDCS2, 1, 0 = 1, 1, 1).
Figure 9-2. Format of Watchdog Timer Mode Register (WDTM)
0
1
×
0
0
1
1
0
0
1
1
6
1
Note 1
Note 2
WDCS0
Low-speed internal oscillation clock (f
System Clock (f
Watchdog timer operation stopped
R/W
0
1
0
1
0
1
0
1
5
1
CHAPTER 9 WATCHDOG TIMER
Note 2
User’s Manual U16898EJ5V0UD
2
2
2
2
2
2
2
2
11
12
13
14
15
16
17
18
WDCS4
oscillation clock operation
During low-speed internal
/f
/f
/f
/f
/f
/f
/f
/f
X
RL
RL
RL
RL
RL
RL
RL
RL
)
4
(4.27 ms)
(8.53 ms)
(17.07 ms)
(34.13 ms)
(68.27 ms)
(136.53 ms)
(273.07 ms)
(546.13 ms)
Operation clock selection
WDCS3
3
Overflow time setting
RL
)
WDCS2
2
2
2
2
2
2
2
2
2
During system clock operation
13
14
15
16
17
18
19
20
/f
/f
/f
/f
/f
/f
/f
/f
X
X
X
X
X
X
X
X
(819.2
(1.64 ms)
(3.28 ms)
(6.55 ms)
(13.11 ms)
(26.21 ms)
(52.43 ms)
(104.86 ms)
WDCS1
1
µ
s)
WDCS0
0