PIC12C672 MICROCHIP [Microchip Technology], PIC12C672 Datasheet - Page 37

• Manufacturer Part Number: PIC12C672
• Description: 8-Pin, 8-Bit CMOS Microcontroller with EEPROM Data Memory
• Manufacturer: MICROCHIP [Microchip Technology]

8.6.1
The WDT has a nominal time-out period of 18 ms,
(with no prescaler). If a longer time-out period is
desired, a prescaler with a division ratio of up to 1:128
can be assigned to the WDT (under software control)
by writing to the OPTION register. Thus, a time-out
period of a nominal 2.3 seconds can be realized.
These periods vary with temperature, V
part process variations (see DC specs).
Under worst case conditions (V
= Max., max. WDT prescaler), it may take several
seconds before a WDT time-out occurs.
FIGURE 8-12: WATCHDOG TIMER BLOCK DIAGRAM
TABLE 8-6:
N/A
Legend: Shaded boxes = Not used by Watchdog Timer, — = unimplemented, read as '0', u = unchanged
Address
1997 Microchip Technology Inc.
WDT PERIOD
OPTION
Name
Note: T0CS, T0SE, PSA, PS2:PS0
SUMMARY OF REGISTERS ASSOCIATED WITH THE WATCHDOG TIMER
Configuration Bit
WDT Enable
GPWU GPPU T0CS T0SE
Watchdog
Bit 7
are bits in the OPTION register.
Timer
From Timer0 Clock Source
(Figure 7-5)
DD
Bit 6
= Min., Temperature
Bit 5
DD
and part-to-
0
1
Bit 4
PSA
M
U
X
Preliminary
Bit 3
PSA
Bit 2
PS2
0
8.6.2
The CLRWDT instruction clears the WDT and the
postscaler, if assigned to the WDT, and prevents it
from timing out and generating a device RESET.
The SLEEP instruction resets the WDT and the
postscaler, if assigned to the WDT. This gives the
maximum SLEEP time before a WDT wake-up reset.
Time-out
8 - to - 1 MUX
WDT
Bit 1 Bit 0
MUX
PS1
Postscaler
Postscaler
1
PS0
WDT PROGRAMMING CONSIDERATIONS
1111 1111
Power-On
Value on
PSA
To Timer0 (Figure 7-4)
Reset
PIC12CE5XX
PS2:PS0
WDT Reset
1111 1111
MCLR and
Value on
DS40172A-page 37
Wake-up on
Pin Change
1111 1111
Value on