PIC18LF2221-I/SP Microchip Technology, PIC18LF2221-I/SP Datasheet - Page 132
![IC PIC MCU FLASH 2KX16 28DIP](/photos/6/59/65908/150-28-dip_sml.jpg)
PIC18LF2221-I/SP
Manufacturer Part Number
PIC18LF2221-I/SP
Description
IC PIC MCU FLASH 2KX16 28DIP
Manufacturer
Microchip Technology
Series
PIC® 18Fr
Datasheets
1.PIC18F2221-ISO.pdf
(402 pages)
2.PIC18F2221-ISO.pdf
(8 pages)
3.PIC18F2221-ISO.pdf
(30 pages)
4.PIC18F2221-ISO.pdf
(46 pages)
5.PIC18LF2221-IML.pdf
(394 pages)
6.PIC18F2321-IML.pdf
(396 pages)
Specifications of PIC18LF2221-I/SP
Core Size
8-Bit
Program Memory Size
4KB (2K x 16)
Core Processor
PIC
Speed
40MHz
Connectivity
I²C, SPI, UART/USART
Peripherals
Brown-out Detect/Reset, HLVD, POR, PWM, WDT
Number Of I /o
25
Program Memory Type
FLASH
Eeprom Size
256 x 8
Ram Size
512 x 8
Voltage - Supply (vcc/vdd)
2 V ~ 5.5 V
Data Converters
A/D 10x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
28-DIP (0.300", 7.62mm)
Controller Family/series
PIC18
No. Of I/o's
25
Eeprom Memory Size
256Byte
Ram Memory Size
512Byte
Cpu Speed
40MHz
No. Of Timers
4
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
- PIC18F2221-ISO PDF datasheet
- PIC18F2221-ISO PDF datasheet #2
- PIC18F2221-ISO PDF datasheet #3
- PIC18F2221-ISO PDF datasheet #4
- PIC18LF2221-IML PDF datasheet #5
- PIC18F2321-IML PDF datasheet #6
- Current page: 132 of 394
- Download datasheet (7Mb)
PIC18F4321 FAMILY
12.3.3
The Timer1 oscillator circuit draws very little power
during operation. Due to the low-power nature of the
oscillator, it may also be sensitive to rapidly changing
signals in close proximity.
The oscillator circuit, shown in Figure 12-3, should be
located as close as possible to the microcontroller.
There should be no circuits passing within the oscillator
circuit boundaries other than V
If a high-speed circuit must be located near the
oscillator (such as the CCP1 pin in Output Compare or
PWM mode, or the primary oscillator using the OSC2
pin), a grounded guard ring around the oscillator circuit,
as shown in Figure 12-4, may be helpful when used on
a single-sided PCB or in addition to a ground plane.
FIGURE 12-4:
12.4
The TMR1 register pair (TMR1H:TMR1L) increments
from 0000h to FFFFh and rolls over to 0000h. The
Timer1 interrupt, if enabled, is generated on overflow
which is latched in interrupt flag bit, TMR1IF
(PIR1<0>). This interrupt can be enabled or disabled
by setting or clearing the Timer1 Interrupt Enable bit,
TMR1IE (PIE1<0>).
DS39689A-page 130
Note: Not drawn to scale.
Timer1 Interrupt
TIMER1 OSCILLATOR LAYOUT
CONSIDERATIONS
OSCILLATOR CIRCUIT
WITH GROUNDED
GUARD RING
SS
V
OSC1
OSC2
RC0
RC1
V
RC2
or V
DD
SS
DD
.
Advance Information
12.5
If either of the CCP modules is configured to use Timer1
and generate a Special Event Trigger in Compare mode
(CCP1M3:CCP1M0 or CCP2M3:CCP2M0 = 1011), this
signal will reset Timer1. The trigger from CCP2 will also
start an A/D conversion if the A/D module is enabled
(see Section 15.3.4 “Special Event Trigger” for more
information).
The module must be configured as either a timer or a
synchronous counter to take advantage of this feature.
When used this way, the CCPRH:CCPRL register pair
effectively becomes a period register for Timer1.
If Timer1 is running in Asynchronous Counter mode,
this Reset operation may not work.
In the event that a write to Timer1 coincides with a
Special Event Trigger, the write operation will take
precedence.
12.6
Adding an external LP oscillator to Timer1 (such as the
one described in Section 12.3 “Timer1 Oscillator”)
gives users the option to include RTC functionality to
their applications. This is accomplished with an
inexpensive watch crystal to provide an accurate time
base and several lines of application code to calculate
the time. When operating in Sleep mode and using a
battery or supercapacitor as a power source, it can
completely eliminate the need for a separate RTC
device and battery backup.
The application code routine, RTCisr, shown in
Example 12-1, demonstrates a simple method to
increment a counter at one-second intervals using an
Interrupt Service Routine. Incrementing the TMR1
register pair to overflow, triggers the interrupt and calls
the routine, which increments the seconds counter by
one. Additional counters for minutes and hours are
incremented as the previous counter overflow.
Since the register pair is 16 bits wide, counting up to
overflow the register directly from a 32.768 kHz clock
would take 2 seconds. To force the overflow at the
required one-second intervals, it is necessary to
preload it. The simplest method is to set the MSb of
TMR1H with a BSF instruction. Note that the TMR1L
register is never preloaded or altered. Doing so may
introduce cumulative errors over many cycles.
For this method to be accurate, Timer1 must operate in
Asynchronous mode and the Timer1 overflow interrupt
must be enabled (PIE1<0> = 1), as shown in the
routine, RTCinit. The Timer1 oscillator must also be
enabled and running at all times.
Note:
Resetting Timer1 Using the CCP
Special Event Trigger
Using Timer1 as a Real-Time Clock
The Special Event Triggers from the
CCP2 module will not set the TMR1IF
interrupt flag bit (PIR1<0>).
© 2005 Microchip Technology Inc.
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