Datasheet

 2011 Microchip Technology Inc. Preliminary DS41576B-page 143
PIC12F752/HV752
17.2 Calibration Bits
The 8 MHz internal oscillator is factory calibrated.
These calibration values are stored in fuses located in
the Calibration Word (2008h). The Calibration Word is
not erased when using the specified bulk erase
sequence in the Memory Programming Specification
(DS41561) and thus, does not require reprogramming.
17.3 Reset
The PIC12F752/HV752 device differentiates between
various kinds of Reset:
a) Power-on Reset (POR)
b) WDT Reset during normal operation
c) WDT Reset during Sleep
d) MCLR
Reset during normal operation
e) MCLR
Reset during Sleep
f) Brown-out Reset (BOR)
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
•MCLR
Reset
•MCLR
Reset during Sleep
• WDT Reset
• Brown-out Reset (BOR)
WDT wake-up does not cause register resets in the
same manner as a WDT Reset since wake-up is
viewed as the resumption of normal operation. TO
and
PD
bits are set or cleared differently in different Reset
situations, as indicated in Tab le 17- 2. Software can use
these bits to determine the nature of the Reset. See
Table 17-4 for a full description of Reset states of all
registers.
A simplified block diagram of the On-Chip Reset Circuit
is shown in Figure 17-1.
The MCLR
Reset path has a noise filter to detect and
ignore small pulses. See Section 20.0 “Electrical
Specifications” for pulse-width specifications.
FIGURE 17-1: SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT
S
RQ
External
Reset
MCLR/VPP pin
V
DD
WDT
Module
V
DD Rise
Detect
On-Chip
WDT
Time-out
Power-on Reset
PWRT
Chip_Reset
11-bit Ripple Counter
Reset
Enable PWRT
Sleep
Brown-out
(1)
Reset
BOREN
Note 1: Refer to the Configuration Word register (Register 17-1).
RC OSC