Datasheet

 2003 Microchip Technology Inc. DS30235J-page 51
PIC16C62X
9.4.5 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. The total time-out will vary based on
oscillator configuration and PWRTE
bit status. For
example, in RC mode with PWRTE
bit erased (PWRT
disabled), there will be no time-out at all. Figure 9-8,
Figure 9-9 and Figure 9-10 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 9-9). This is useful for testing purposes or
to synchronize more than one PIC16C62X device
operating in parallel.
Table 9-4 shows the RESET conditions for some
special registers, while Table 9-5 shows the RESET
conditions for all the registers.
9.4.6 POWER CONTROL (PCON)/
STATUS REGISTER
The power control/STATUS register, PCON (address
8Eh), has two bits.
Bit0 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 (by setting BODEN bit = 0
in the Configuration word).
Bit1 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 must have occurred (V
DD may have
gone too low).
TABLE 9-1: TIME-OUT IN VARIOUS SITUATIONS
TABLE 9-2: STATUS/PCON BITS AND THEIR SIGNIFICANCE
Legend: u = unchanged, x = unknown
Oscillator Configuration
Power-up
Brown-out Reset
Wake-up
from SLEEP
PWRTE
= 0 PWRTE = 1
XT, HS, LP 72 ms + 1024 T
OSC 1024 TOSC 72 ms + 1024 TOSC 1024 TOSC
RC 72 ms — 72 ms —
POR BOR TO PD
0X11Power-on Reset
0X0XIllegal, TO
is set on POR
0XX0Illegal, PD is set on POR
10XXBrown-out Reset
110uWDT Reset
1100WDT Wake-up
11uuMCLR
Reset during normal operation
1110MCLR
Reset during SLEEP
TABLE 9-3: SUMMARY OF REGISTERS ASSOCIATED WITH BROWN-OUT
Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Value on
POR Reset
Value on all
other
RESETS
(1)
83h STATUS
TO PD 0001 1xxx 000q quuu
8Eh PCON
— — — — — —PORBOR ---- --0x ---- --uq
Legend: u = unchanged, x = unknown, - = unimplemented bit, reads as ‘0’, q = value depends on condition.
Note 1: Other (non Power-up) Resets include MCLR
Reset, Brown-out Reset and Watchdog Timer Reset during
normal operation.