Renesas M16C Series User Manual page 55

M30240 Group
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, 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.
Internal clock Φ
Write to the watchdog
timer start register
(address 000E
Figure 1.21: Block diagram of watchdog timer
Watchdog timer control register (Note)
b7 b6
0
Watchdog timer start register
b7
Figure 1.22: Watchdog timer control and start registers
Rev.1.00 Sep 24, 2003 Page 37 of 360
1/16
1/128
Prescaler
)
16
RESET
b5 b4 b3 b2 b1 b0
Symbol
0
WDC
Bit symbol
High-order bit of Watchdog timer
Reserved bit
WDC7
Note: Set the desired prescale value before initializing the Watchdog timer.
b0
Symbol
WDTS
The Watchdog timer is initialized and starts counting after the first write instruction
to this register after reset. Writing any value to this register resets the counter to
7FFF 16.
WDC7 = 0
Watchdog timer
WDC7 = 1
Set to 7FFF
16
Address When reset
000F 000XXXXX
16
Bit name
Must always be set to "0"
0 : Divided by 16
Prescaler select bit
1 : Divided by 128
Address When reset
000E Indeterminate
16
Function
Watchdog Timer
).
16
Watchdog timer
interrupt request
2
Function R W
R W
) and
16