PIC18F2550-I/SP Microchip Technology, PIC18F2550-I/SP Datasheet - Page 29

• Manufacturer Part Number: PIC18F2550-I/SP
• Description: IC PIC MCU FLASH 16KX16 28DIP
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F2550-I/SP

• Program Memory Type: FLASH
• Program Memory Size: 32KB (16K x 16)
• Package / Case: 28-DIP (0.300", 7.62mm)
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 48MHz
• Connectivity: I²C, SPI, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, HLVD, POR, PWM, WDT
• Number Of I /o: 24
• Eeprom Size: 256 x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 10x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC18F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 1536 B
• Interface Type: SPI, I2C, EAUSART
• Maximum Clock Frequency: 48 MHz
• Number Of Programmable I/os: 24
• Number Of Timers: 4
• Operating Supply Voltage: 2 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734, 52712-325, EWPIC18
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, ICE4000, DM163025, DV164136
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 10 Channel
• Package: 28SPDIP
• Device Core: PIC
• Family Name: PIC18
• Maximum Speed: 48 MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: I3-DB18F4550 - BOARD DAUGHTER ICEPIC3DM163025 - PIC DEM FULL SPEED USB DEMO BRDDVA18XP280 - DEVICE ADAPTER 18F2220 PDIP 28LD
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

2.2.5
The PIC18F2455/2550/4455/4550 devices include an
internal oscillator block which generates two different
clock signals; either can be used as the microcontroller’s
clock source. If the USB peripheral is not used, the
internal oscillator may 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 device clock. It
also drives the INTOSC postscaler which can provide a
range of clock frequencies from 31 kHz to 4 MHz. The
INTOSC output is enabled when a clock frequency
from 125 kHz to 8 MHz is selected.
The other clock source is the internal RC oscillator
(INTRC) which provides a nominal 31 kHz output.
INTRC is enabled if it is selected as the device clock
source; it is also enabled automatically 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 25.0 “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 (page 32).
2.2.5.1
When the internal oscillator is used as the micro-
controller clock source, one of the other oscillator
modes (External Clock or External Crystal/Resonator)
must be used as the USB clock source. The choice of
the USB clock source is determined by the particular
internal oscillator mode.
There are four distinct modes available:
1.
2.
3.
4.
Of these four modes, only INTIO mode frees up an
additional pin (OSC2/CLKO/RA6) for port I/O use.
© 2006 Microchip Technology Inc.
INTHS mode: The USB clock is provided by the
oscillator in HS mode.
INTXT mode: The USB clock is provided by the
oscillator in XT mode.
INTCKO mode: The USB clock is provided by an
external clock input on OSC1/CLKI; the OSC2/
CLKO pin outputs F
INTIO mode: The USB clock is provided by an
external clock input on OSC1/CLKI; the OSC2/
CLKO pin functions as a digital I/O (RA6).
INTERNAL OSCILLATOR BLOCK
Internal Oscillator Modes
OSC
/4.
PIC18F2455/2550/4455/4550
Preliminary
2.2.5.2
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 within 8 clock cycles (approximately,
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.
The OSCTUNE register also contains the INTSRC bit.
The INTSRC bit allows users to select which internal
oscillator provides the clock source when the 31 kHz
frequency option is selected. This is covered in greater
detail in Section 2.4.1 “Oscillator Control Register”.
2.2.5.3
The internal oscillator block is calibrated at the factory
to produce an INTOSC output frequency of 8.0 MHz.
However, this frequency may drift as V
ture changes, which can affect the controller operation
in a variety of ways.
The low-frequency INTRC oscillator operates indepen-
dently of the INTOSC source. Any changes in INTOSC
across voltage and temperature are not necessarily
reflected by changes in INTRC and vice versa.
OSCTUNE Register
Internal Oscillator Output Frequency
and Drift
DS39632C-page 27
DD
or tempera-