PIC18F4455-I/P Microchip Technology, PIC18F4455-I/P Datasheet - Page 30

• Manufacturer Part Number: PIC18F4455-I/P
• Description: IC PIC MCU FLASH 12KX16 40DIP
• Manufacturer: Microchip Technology
• Series: PIC® 18Fr

Specifications of PIC18F4455-I/P

• Program Memory Type: FLASH
• Program Memory Size: 24KB (12K x 16)
• Package / Case: 40-DIP (0.600", 15.24mm)
• 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: 35
• Eeprom Size: 256 x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 13x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC18F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 2 KB
• Interface Type: SPI/I2C/EAUSART
• Maximum Clock Frequency: 48 MHz
• Number Of Programmable I/os: 35
• 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, DV164136, DM163025
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 13-ch x 10-bit
• Package: 40PDIP
• 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 BRDDVA18XP400 - DEVICE ADAPTER 18F4220 PDIP 40LD444-1001 - DEMO BOARD FOR PICMICRO MCUACICE0206 - ADAPTER MPLABICE 40P 600 MIL
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PIC18F2455/2550/4455/4550
REGISTER 2-1:
2.2.5.4
It is possible to adjust the INTOSC frequency by
modifying the value in the OSCTUNE register. This has
no effect on the INTRC clock source frequency.
Tuning the INTOSC source requires knowing when to
make the adjustment, in which direction it should be
made and in some cases, how large a change is
needed. When using the EUSART, for example, an
adjustment may be required when it begins to generate
framing errors or receives data with errors while in
Asynchronous mode. Framing errors indicate that the
device clock frequency is too high; to adjust for this,
decrement the value in OSCTUNE to reduce the clock
frequency. On the other hand, errors in data may sug-
gest that the clock speed is too low; to compensate,
increment OSCTUNE to increase the clock frequency.
It is also possible to verify device clock speed against
a reference clock. Two timers may be used: one timer
is clocked by the peripheral clock, while the other is
clocked by a fixed reference source, such as the
Timer1 oscillator. Both timers are cleared but the timer
clocked by the reference generates interrupts. When
DS39632C-page 28
bit 7
Legend:
R = Readable bit
-n = Value at POR
bit 7
bit 6-5
bit 4-0
INTSRC
R/W-0
Compensating for INTOSC Drift
INTSRC: Internal Oscillator Low-Frequency Source Select bit
1 = 31.25 kHz device clock derived from 8 MHz INTOSC source (divide-by-256 enabled)
0 = 31 kHz device clock derived directly from INTRC internal oscillator
Unimplemented: Read as ‘0’
TUN4:TUN0: Frequency Tuning bits
01111 = Maximum frequency
•
•
00001
00000 = Center frequency. Oscillator module is running at the calibrated frequency.
11111
•
•
10000 = Minimum frequency
U-0
—
OSCTUNE: OSCILLATOR TUNING REGISTER
W = Writable bit
‘1’ = Bit is set
U-0
•
•
•
•
—
R/W-0
TUN4
Preliminary
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
R/W-0
TUN3
an interrupt occurs, the internally clocked timer is read
and both timers are cleared. If the internally clocked
timer value is greater than expected, then the internal
oscillator block is running too fast. To adjust for this,
decrement the OSCTUNE register.
Finally, a CCP module can use free-running Timer1 (or
Timer3), clocked by the internal oscillator block and an
external event with a known period (i.e., AC power
frequency). The time of the first event is captured in the
CCPRxH:CCPRxL registers and is recorded for use
later. When the second event causes a capture, the
time of the first event is subtracted from the time of the
second event. Since the period of the external event is
known, the time difference between events can be
calculated.
If the measured time is much greater than the calcu-
lated time, the internal oscillator block is running too
fast; to compensate, decrement the OSCTUNE register.
If the measured time is much less than the calculated
time, the internal oscillator block is running too slow; to
compensate, increment the OSCTUNE register.
R/W-0
TUN2
© 2006 Microchip Technology Inc.
x = Bit is unknown
R/W-0
TUN1
R/W-0
TUN0
bit 0