PIC16C621A Microchip Technology Inc., PIC16C621A Datasheet - Page 51

• Manufacturer Part Number: PIC16C621A
• Description: Eprom-based 8-bit Cmos Microcontrollers
• Manufacturer: Microchip Technology Inc.

9.3
The PIC16C62X differentiates between various kinds
of RESET:
a)
b)
c)
d)
e)
f)
Some registers are not affected in any RESET
condition Their status is unknown on POR and
unchanged in any other RESET. Most other registers
are reset to a “RESET state” on Power-on Reset,
FIGURE 9-6:
 2003 Microchip Technology Inc.
V
MCLR/
OSC1/
CLKIN
PP
V
Pin
Note 1: This is a separate oscillator from the RC oscillator of the CLKIN pin.
Power-on Reset (POR)
MCLR Reset during normal operation
MCLR Reset during SLEEP
WDT Reset (normal operation)
WDT wake-up (SLEEP)
Brown-out Reset (BOR)
DD
Pin
RESET
On-chip
RC OSC
OST/PWRT
Brown-out
V
Module
(1)
detect
WDT
DD
Reset
rise
OST
SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
PWRT
10-bit Ripple-counter
Reset
10-bit Ripple-counter
WDT
Time-out
BODEN
Power-on Reset
External
RESET
SLEEP
Enable PWRT
Enable OST
MCLR Reset, WDT Reset and MCLR Reset during
SLEEP. They are not affected by a WDT wake-up,
since this is viewed as the resumption of normal
operation. TO and PD bits are set or cleared differently
in different RESET situations as indicated in Table 9-2.
These bits are used in software to determine the nature
of the RESET. See Table 9-5 for a full description of
RESET states of all registers.
A simplified block diagram of the on-chip RESET circuit
is shown in Figure 9-6.
The MCLR Reset path has a noise filter to detect and
ignore small pulses. See Table 12-5 for pulse width
specification.
See Table 9-1 for time-out situations.
PIC16C62X
S
R
DS30235J-page 49
Q
Q
Chip_Reset