PIC18F1320-I/SO Microchip Technology Inc., PIC18F1320-I/SO Datasheet - Page 16

• Manufacturer Part Number: PIC18F1320-I/SO
• Description: Microcontroller; 8 KB Flash; 256 RAM; 256 EEPROM; 16 I/O; 18-Pin-PDIP
• Manufacturer: Microchip Technology Inc.

Specifications of PIC18F1320-I/SO

• A/d Inputs: 7-Channel, 10-Bit
• Cpu Speed: 10 MIPS
• Eeprom Memory: 256 Bytes
• Input Output: 16
• Interface: USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 18-pin SOIC
• Programmable Memory: 8K Bytes
• Ram Size: 256 Bytes
• Speed: 20 MHz
• Timers: 1-8-bit, 3-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC18F1220/1320
2.6
The PIC18F1220/1320 devices include an internal
oscillator block, which generates two different clock
signals; either can be used as the system’s clock
source. This can eliminate the need for external
oscillator circuits on the OSC1 and/or OSC2 pins.
The main output (INTOSC) is an 8 MHz clock source,
which can be used to directly drive the system clock. It
also drives a postscaler, which can provide a range of
clock frequencies from 125 kHz to 4 MHz. The
INTOSC output is enabled when a system clock
frequency from 125 kHz to 8 MHz is selected.
The other clock source is the internal RC oscillator
(INTRC), which provides a 31 kHz output. The INTRC
oscillator is enabled by selecting the internal oscillator
block as the system clock source, or when any of the
following are enabled:
• Power-up Timer
• Fail-Safe Clock Monitor
• Watchdog Timer
• Two-Speed Start-up
These features are discussed in greater detail in
Section 19.0 “Special Features of the CPU”.
The clock source frequency (INTOSC direct, INTRC
direct or INTOSC postscaler) is selected by configuring
the IRCF bits of the OSCCON register (Register 2-2).
2.6.1
Using the internal oscillator as the clock source can
eliminate the need for up to two external oscillator pins,
which can then be used for digital I/O. Two distinct
configurations are available:
• In INTIO1 mode, the OSC2 pin outputs F
• In INTIO2 mode, OSC1 functions as RA7 and
DS39605C-page 14
while OSC1 functions as RA7 for digital input and
output.
OSC2 functions as RA6, both for digital input and
output.
Internal Oscillator Block
INTIO MODES
OSC
/4,
2.6.2
The internal oscillator block is calibrated at the factory
to produce an INTOSC output frequency of 8.0 MHz
(see Table 22-6). This changes the frequency of the
INTRC source from its nominal 31.25 kHz. Peripherals
and features that depend on the INTRC source will be
affected by this shift in frequency.
Once set during factory calibration, the INTRC
frequency will remain within ±2% as temperature and
V
ranges.
2.6.3
The internal oscillator’s output has been calibrated at
the factory, but can be adjusted in the user’s applica-
tion. This is done by writing to the OSCTUNE register
(Register 2-1). The tuning sensitivity is constant
throughout the tuning range.
When the OSCTUNE register is modified, the INTOSC
and INTRC frequencies will begin shifting to the new
frequency. The INTRC clock will reach the new
frequency
8 * 32 s = 256 s). The INTOSC clock will stabilize
within 1 ms. Code execution continues during this shift.
There is no indication that the shift has occurred.
Operation of features that depend on the INTRC clock
source frequency, such as the WDT, Fail-Safe Clock
Monitor and peripherals, will also be affected by the
change in frequency.
DD
change across their full specified operating
INTRC OUTPUT FREQUENCY
OSCTUNE REGISTER
within
8 clock
 2004 Microchip Technology Inc.
cycles
(approximately