FUJITSU Semiconductor Controller MB89950/950A - Manual (Page 129)

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CHAPTER 6 WATCHDOG TIMER
6.3 Watchdog Timer Control Register (WDTC)
The watchdog timer control register (WDTC) is used to activate or clear the watchdog
timer.
■ Watchdog timer control register (WDTC)
Figure 6.3-1 Watchdog timer control register (WDTC)
Address Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Initial value
0009 H WTE3 WTE2 WTE1 WTE0 ----XXXX
W W W W
WTE3 WTE2 WTE1 WTE0 Watchdog timer cont rol bi ts
0 1 0 1
Activate the watchdog timer
(when writing for the first time
after a reset).
Clear the watchdog timer
(when writing for the second and
subsequent times after a reset).
Other than the above No operation
Note: As the bit 3-0 are write-only, the bit manipulation instructions for these bits cannot be used.
W : Write-only
— : Unused
X : Indeterminate
Table 6.3-1 Watchdog timer control register (WDTC) bits
Bit Function
Bit 7
Bit 6
Bit 5
Bit 4 Unused bits • The read value is indeterminate.
• Writing to these bits has no effect on operation.
Bit 3
Bit 2
Bit 1
Bit 0 WTE3, WTE0:
Watchdog timer
control bits • Writing "0101
B
" to these bits activates (when writing for the first time after a reset) or
clears (when writing for the second and subsequent times after a reset) the watchdog
timer.
• Writing a value other than "0101
B
" has no effect on the operation.
Note:
The read value is always "1111
B
". The bit manipulation instructions cannot be used.