
2001 Microchip Technology Inc.
DS35007B-page 31
PIC16F84A
6.10.2
WDT PROGRAMMING
CONSIDERATIONS
It should also be taken into account that under worst
case conditions (VDD = Min., Temperature = Max., Max.
WDT Prescaler), it may take several seconds before a
WDT time-out occurs.
FIGURE 6-11:
WATCHDOG TIMER BLOCK DIAGRAM
TABLE 6-7:
SUMMARY OF REGISTERS ASSOCIATED WITH THE WATCHDOG TIMER
From TMR0 Clock Source
Postscaler
WDT Timer
M
U
X
PSA
8 - to -1 MUX
PSA
WDT
Time-out
1
0
1
WDT
Enable Bit
PS2:PS0
8
MUX
Note:
PSA and PS2:PS0 are bits in the OPTION_REG register.
Addr
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
Power-on
Reset
Value on all
other
RESETS
2007h
Config. bits
(2)
PWRTE(1)
WDTE
FOSC1
FOSC0
(2)
81h
OPTION_REG
RBPU
INTEDG
T0CS
T0SE
PSA
PS2
PS1
PS0
1111 1111 1111 1111
Legend: x = unknown. Shaded cells are not used by the WDT.
Note