PIC16F7X
12.3
RESET
The PIC16F7X differentiates between various kinds of
RESET:
•
•
•
•
•
•
Power-on Reset (POR)
MCLR Reset during normal operation
MCLR Reset during SLEEP
WDT Reset (during normal operation)
WDT Wake-up (during SLEEP)
Brown-out Reset (BOR)
Some registers are not affected in any RESET condi-
tion. 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 (POR), on the
MCLR and WDT Reset, on MCLR Reset during
SLEEP, and Brown-out Reset (BOR). They are not
affected by a WDT Wake-up, which is viewed as the
resumption of normal operation. The TO and PD bits
are set or cleared differently in different RESET situa-
tions, as indicated in Table 12-4. These bits are used in
software to determine the nature of the RESET. See
registers.
A simplified block diagram of the on-chip RESET circuit
is shown in Figure 12-4.
FIGURE 12-4:
SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
External
RESET
MCLR
SLEEP
WDT
Module
V
DD
Rise
Detect
V
DD
Brown-out
Reset
BODEN
OST/PWRT
OST
10-bit Ripple Counter
OSC1
(1)
On-chip
RC OSC
Chip_Reset
R
Q
Power-on Reset
S
WDT
Time-out
Reset
PWRT
10-bit Ripple Counter
Enable PWRT
Enable OST
Note 1:
This is a separate oscillator from the RC oscillator of the CLKIN pin.
2002 Microchip Technology Inc.
DS30325B-page 93
MICROCHIP [ MICROCHIP TECHNOLOGY ]
