M306V0ME Mitsubishi, M306V0ME Datasheet - Page 67

• Manufacturer Part Number: M306V0ME
• Description: SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER and ON-SCREEN DISPLAY CONTROLLER
• Manufacturer: Mitsubishi

Rev. 1.0
2.8 Watchdog Timer
The watchdog timer has the function of detecting when the program is out of control. The watchdog timer is
a 15-bit counter which down-counts the clock derived by dividing the BCLK using the prescaler. A watchdog
timer interrupt is generated when an underflow occurs in the watchdog timer. When X
BCLK bit 7 of the watchdog timer control register (address 000F
16 or by 128). When X
of the watchdog timer control register (address 000F
lated as given below. The watchdog timer’s period is, however, subject to an error due to the pre-scaler.
With X
Watchdog timer period =
With X
Watchdog timer period =
For example suppose that BCLK runs at 10 MHz and that 16 has been chosen for the dividing ratio of the
pre-scaler, then the watchdog timer’s period becomes approximately 52.4 ms.
The watchdog timer is initialized by writing to the watchdog timer start register (address 000E
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 2.8.1 shows the block diagram of the watchdog timer. Figure 2.8.2 shows the watchdog timer control
register and Figure 2.8.3 shows the watchdog timer start register.
IN
CIN
chosen for BCLK
chosen for BCLK
CIN
is selected as the BCLK , the prescaler is set for division by 2 regardless of bit 7
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
pre-scaler dividing ratio (16 or 128)
pre-scaler dividing ratio (2)
16
). Thus the watchdog timer’s period can be calcu-
16
BCLK
).
watchdog timer count (32768)
BCLK
16
) selects the prescaler division ratio (by
and ON-SCREEN DISPLAY CONTROLLER
watchdog timer count (32768)
MITSUBISHI MICROCOMPUTERS
M306V0ME-XXXFP
IN
M306V0EEFP
is selected for the
16
) and when
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