PIC16F84A_07 Datasheet, PDF (33/88 Pages) Microchip Technology – 18-pin Enhanced FLASH/EEPROM 8-bit Microcontroller

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
From TMR0 Clock Source
(Figure 5-2)
WDT Timer
0M
• ^1U
X
WDT
Enable Bit
PSA
Postscaler
8
8 - to -1 MUX
PS2:PS0
•
0
1
MUX
To TMR0 (Figure 5-2)
PSA
WDT
Time-out
Note: PSA and PS2:PS0 are bits in the OPTION_REG register.
TABLE 6-7: SUMMARY OF REGISTERS ASSOCIATED WITH THE WATCHDOG TIMER
Addr
Name
Bit 7 Bit 6 Bit 5 Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on Value on all
Power-on other
Reset
RESETS
2007h Config. bits
(2)
(2)
(2)
(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 1: See Register 6-1 for operation of the PWRTE bit.
2: See Register 6-1 and Section 6.12 for operation of the code and data protection bits.
© 2001 Microchip Technology Inc.
DS35007B-page 31