Rainbow Electronics T89C51CC01 User Manual
Page 69
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T89C51CC01
Rev. D – 17-Dec-01
interrupt is pulled high. It is suggested that the WDT be reset during the interrupt service
for the interrupt used to exit Power Down.
To ensure that the WDT does not overflow within a few states of exiting powerdown, it is
best to reset the WDT just before entering powerdown.
In the Idle mode, the oscillator continues to run. To prevent the WDT from resetting
T89C51CC01 while in Idle mode, the user should always set up a timer that will periodi-
cally exit Idle, service the WDT, and re-enter Idle mode.
14.2.1 Register
Table 34. WDTPRG Register
WDTPRG (S:A7h)
WatchDog Timer Duration
Programming register
Reset Value = XXXX X000b
7
6
5
4
3
2
1
0
-
-
-
-
-
S2
S1
S0
Bit
Number
Bit
Mnemonic
Description
7
-
Reserved
The value read from this bit is indeterminate. Do not set this bit.
6
-
Reserved
The value read from this bit is indeterminate. Do not set this bit.
5
-
Reserved
The value read from this bit is indeterminate. Do not set this bit.
4
-
Reserved
The value read from this bit is indeterminate. Do not set this bit.
3
-
Reserved
The value read from this bit is indeterminate. Do not set this bit.
2
S2
WatchDog Timer Duration selection bit 2
Work in conjunction with bit 1 and bit 0.
1
S1
WatchDog Timer Duration selection bit 1
Work in conjunction with bit 2 and bit 0.
0
S0
WatchDog Timer Duration selection bit 0
Work in conjunction with bit 1 and bit 2.