Datasheet

Table Of Contents
© 2007 Microchip Technology Inc. DS41270E-page 39
PIC10F220/222
FIGURE 8-6: WATCHDOG TIMER BLOCK DIAGRAM
TABLE 8-4: SUMMARY OF REGISTERS ASSOCIATED WITH THE WATCHDOG TIMER
8.7 Time-out Sequence, Power-down
and Wake-up from Sleep Status
Bits (TO
/PD/GPWUF/CWUF)
The TO, PD and GPWUF bits in the STATUS register
can be tested to determine if a Reset condition has
been caused by a Power-up condition, a MCLR,
Watchdog Timer (WDT) Reset or wake-up on pin
change.
TABLE 8-5: TO/PD/GPWUF STATUS AFTER RESET
Address 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
N/A OPTION
GPWU GPPU T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111
Legend: Shaded boxes = Not used by Watchdog Timer, – = unimplemented, read as ‘0’, u = unchanged.
(Figure 6-5)
Postscaler
Note 1: T0CS, T0SE, PSA, PS<2:0> are bits in the OPTION register.
WDT Time-out
Watchdog
Timer
From Timer0 Clock Source
WDT Enable
Configuration
Bit
PSA
Postscaler
8-to-1 MUX
PS<2:0>
(Figure 6-4)
To Timer0
0
1
M
U
X
1
0
PSA
MUX
3
GPWUF TO PD Reset Caused By
000WDT wake-up from Sleep
00uWDT time-out (not from Sleep)
010MCLR
wake-up from Sleep
011Power-up
0uuMCLR
not during Sleep
110Wake-up from Sleep on pin change
Legend: u = unchanged, x = unknown, – = unimplemented bit, read as ‘0’, q = value depends on condition.
Note 1: The TO, PD and GPWUF bits maintain their status (u) until a Reset occurs. A low-pulse on the MCLR
input does not change the TO
, PD or GPWUF Status bits.