Datasheet

PIC16F610/616/16HV610/616
DS41288F-page 114 © 2009 Microchip Technology Inc.
12.3.5 TIME-OUT SEQUENCE
On power-up, the time-out sequence is as follows:
• PWRT time-out is invoked after POR has expired.
• OST is activated after the PWRT time-out has
expired.
The total time-out will vary based on oscillator
configuration and PWRTE
bit status. For example, in EC
mode with PWRTE
bit erased (PWRT disabled), there
will be no time-out at all. Figure 12-4, Figure 12-5 and
Figure 12-6 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 12-5). This is useful for testing purposes or
to synchronize more than one PIC16F610/616/
16HV610/616 device operating in parallel.
Table 12-5 shows the Reset conditions for some
special registers, while Table 12-4 shows the Reset
conditions for all the registers.
12.3.6 POWER CONTROL (PCON)
REGISTER
The Power Control register PCON (address 8Eh) has
two Status bits to indicate what type of Reset occurred
last.
Bit 0 is BOR
(Brown-out). 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 subse-
quent 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 12.3.4 “Brown-out
Reset (BOR)”.
TABLE 12-1: TIME-OUT IN VARIOUS SITUATIONS
TABLE 12-2: STATUS/PCON BITS AND THEIR SIGNIFICANCE
TABLE 12-3: SUMMARY OF REGISTERS ASSOCIATED WITH BROWN-OUT RESET
Oscillator Configuration
Power-up Brown-out Reset
Wake-up from
Sleep
PWRTE
= 0 PWRTE = 1 PWRTE = 0 PWRTE = 1
XT, HS, LP T
PWRT + 1024 •
T
OSC
1024 • TOSC TPWRT + 1024 •
T
OSC
1024 • TOSC 1024 • TOSC
RC, EC, INTOSC TPWRT —TPWRT ——
POR
BOR TO PD Condition
0x11Power-on Reset
u011Brown-out Reset
uu0uWDT Reset
uu00WDT Wake-up
uuuuMCLR
Reset during normal operation
uu10MCLR
Reset during Sleep
Legend: u = unchanged, x = unknown
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Value on
POR, BOR
Value on
all other
Resets
(1)
PCON — — — — — —PORBOR ---- --qq ---- --uu
STATUS
IRP RP1 RP0 TO PD Z DC C 0001 1xxx 000q quuu
Legend: u = unchanged, x = unknown, – = unimplemented bit, reads as ‘0’, q = value depends on condition.
Shaded cells are not used by BOR.
Note 1: Other (non Power-up) Resets include MCLR
Reset and Watchdog Timer Reset during normal operation.