Datasheet

PIC16(L)F722A/723A
DS41417B-page 32  2010-2012 Microchip Technology Inc.
3.6 Time-out Sequence
On power-up, the time-out sequence is as follows: first,
PWRT time-out is invoked after POR has expired, then
OST is activated after the PWRT time-out has expired.
The total time-out will vary based on oscillator configu-
ration and PWRTE
bit status. For example, in EC mode
with PWRTE
bit = 1 (PWRT disabled), there will be no
time-out at all. Figure 3-4, Figure 3-5 and Figure 3-6
depict time-out sequences.
Since the time-outs occur from the POR pulse, if MCLR
is kept low long enough, the time-outs will expire. Then,
bringing MCLR
high will begin execution immediately
(see Figure 3-5). This is useful for testing purposes or
to synchronize more than one PIC16(L)F722A/723A
device operating in parallel.
Table 3-3 shows the Reset conditions for some special
registers.
3.7 Power Control (PCON) Register
The Power Control (PCON) register has two Status bits
to indicate what type of Reset that last occurred.
Bit 0 is BOR
(Brown-out Reset). BOR is unknown on
Power-on Reset. It must then be set by the user and
checked on subsequent Resets to see if BOR = 0,
indicating that a brown-out has occurred. The BOR
Status bit is a “don’t care” and is not necessarily
predictable if the brown-out circuit is disabled
(BOREN<1:0> = 00 in the Configuration Word register).
Bit 1 is POR
(Power-on Reset). It is a ‘0’ on Power-on
Reset and unaffected otherwise. The user must write a
‘1’ to this bit following a Power-on Reset. On a
subsequent Reset, if POR
is ‘0’, it will indicate that a
Power-on Reset has occurred (i.e., V
DD may have
gone too low).
For more information, see Section 3.5 “Brown-Out
Reset (BOR)”.
TABLE 3-2: TIME-OUT IN VARIOUS SITUATIONS
TABLE 3-3: RESET BITS AND THEIR SIGNIFICANCE
Oscillator Configuration
Power-up Brown-out Reset
Wake-up from
Sleep
PWRTE = 0 PWRTE = 1 PWRTE = 0 PWRTE = 1
XT, HS, LP
(1)
TPWRT + 1024 •
T
OSC
1024 • TOSC TPWRT + 1024 •
T
OSC
1024 • TOSC 1024 • TOSC
RC, EC, INTOSC TPWRT —TPWRT ——
Note 1: LP mode with T1OSC disabled.
POR
BOR TO PD Condition
0u11Power-on Reset
1011Brown-out Reset
uu0uWDT Reset
uu00WDT Wake-up
uuuuMCLR
Reset during normal operation
uu10MCLR
Reset during Sleep
Legend: u = unchanged, x = unknown