M30240ECFP MITSUBISHI [Mitsubishi Electric Semiconductor], M30240ECFP Datasheet - Page 39

• Manufacturer Part Number: M30240ECFP
• Description: M30240 Group Specification
• Manufacturer: MITSUBISHI [Mitsubishi Electric Semiconductor]

Preliminary Specifications REV. E
Specifications in this manual are tentative and subject to change
Watchdog Timer
2.16 Watchdog Timer
Table 1.12:
CM06
The watchdog timer has the function of detecting when the program is out of control. The watchdog timer
is 39a 15-bit counter that decrements using the clock derived by dividing the internal clock
prescaler. A watchdog timer interrupt is generated when an underflow occurs in the watchdog timer. Bit
7 of the watchdog timer control register (address 000F
128). Table 1.12 shows the periodic table for the watchdog timer.
The watchdog timer is initialized by writing to the watchdog timer start register (address 000E
when a watchdog timer interrupt request is generated. The prescaler is initialized only when the
microcomputer is reset. After a reset is cancelled, the watchdog timer and prescaler are both stopped.
The count is started by writing to the watchdog timer start register (address 000E
Figure 1.21 shows the block diagram of the watchdog timer. Figure 1.22 shows the watchdog timer-
related registers.
0
0
0
0
1
Watchdog timer periodic table (f(X
Invalid
CM17
0
0
1
1
Invalid
CM16
0
1
0
1
0.625MHz
1.25MHz
Internal
2.5MHz
clock
10MHz
5MHz
1-39
IN
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
)=10MHz)
WDC7
16
0
1
0
1
0
1
0
1
0
1
) selects the prescaler division ratio (by 16 or
Approx. 52.4ms
Approx. 419.2ms
Approx. 104.9ms
Approx. 838.8ms
Approx. 209.7ms
Approx. 1.68s
Approx. 838.8ms
Approx. 6.71s
Approx. 419.2ms
Approx. 3.35s
Mitsubishi microcomputers
M30240 Group
16
Period
).
using the
16
) and