PIC12F519 Microchip Technology, PIC12F519 Datasheet - Page 41

• Manufacturer Part Number: PIC12F519
• Description: 8-Bit Flash Microcontroller
• Manufacturer: Microchip Technology

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8.2.5
The internal RC oscillator provides a fixed 4/8 MHz
(nominal) system clock at V
Section 11.0
information on variation over voltage and temperature).
In addition, a calibration instruction is programmed into
the last address of memory, which contains the calibra-
tion value for the internal RC oscillator. This location is
always
code-protect settings. This value is programmed as a
MOVLW XX instruction where XX is the calibration value,
and is placed at the Reset vector. This will load the W
register with the calibration value upon Reset and the
PC will then roll over to the users program at address
0x000. The user then has the option of writing the value
to the OSCCAL Register (05h) or ignoring it.
OSCCAL, when written to with the calibration value, will
“trim” the internal oscillator to remove process variation
from the oscillator frequency.
For the PIC12F519 device, only bits <7:1> of OSCCAL
are used for calibration. See Register 4-3 for more
information.
© 2007 Microchip Technology Inc.
Note:
Note:
non-code
INTERNAL 4/8 MHz RC
OSCILLATOR
Erasing the device will also erase the
pre-programmed internal calibration value
for the internal oscillator. The calibration
value must be read prior to erasing the
part so it can be reprogrammed correctly
later.
The bit 0 of the OSCCAL register is
unimplemented and should be written as
‘0’
compatibility with future devices.
“Electrical
when
protected,
modifying
DD
Characteristics”
= 5V and 25°C, (see
regardless
OSCCAL
of
Preliminary
for
the
for
8.3
The device differentiates between various kinds of
Reset:
• Power-on Reset (POR)
• MCLR Reset during normal operation
• MCLR Reset during Sleep
• WDT Time-out Reset during normal operation
• WDT Time-out Reset during Sleep
• Wake-up from Sleep on pin change
Some registers are not reset in any way, and they are
unknown on Power-on Reset (POR) and unchanged in
any other Reset. Most other registers are reset to
“Reset state” on Power-on Reset (POR), MCLR, WDT
or Wake-up on pin change Reset during normal opera-
tion. They are not affected by a WDT Reset during
Sleep or MCLR Reset during Sleep, since these
Resets are viewed as resumption of normal operation.
The exceptions to this are TO, PD and RBWUF bits.
They are set or cleared differently in different Reset sit-
uations. These bits are used in software to determine
the nature of Reset. See Table 8-3 for a full description
of Reset states of all registers.
Reset
PIC12F519
DS41319A-page 39