收藏本站
参数资料
型号： PIC18LF2450T-I/SO
厂商： Microchip Technology
文件页数： 25/143页
文件大小： 0K
描述： IC PIC MCU FLASH 8KX16 28SOIC
标准包装： 1,600
系列： PIC® 18F
核心处理器： PIC
芯体尺寸： 8-位
速度： 48MHz
连通性： UART/USART，USB
外围设备： 欠压检测/复位，HLVD，POR，PWM，WDT
输入/输出数： 23
程序存储器容量： 16KB（8K x 16）
程序存储器类型： 闪存
RAM 容量： 768 x 8
电压 - 电源 (Vcc/Vdd)： 2 V ~ 5.5 V
数据转换器： A/D 10x10b
振荡器型： 内部
工作温度： -40°C ~ 85°C
封装/外壳： 28-SOIC（0.295"，7.50mm 宽）
包装： 带卷 (TR)
PIC18F2450/4450
DS39760A-page 118
Advance Information
2006 Microchip Technology Inc.
11.3.3
TIMER1 OSCILLATOR LAYOUT
CONSIDERATIONS
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 11-3, should be
located as close as possible to the microcontroller.
There should be no circuits passing within the oscillator
circuit boundaries other than VSS or VDD.
If a high-speed circuit must be located near the oscilla-
tor (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 11-4, may be helpful when used on a
single-sided PCB or in addition to a ground plane.
FIGURE 11-4:
OSCILLATOR CIRCUIT
WITH GROUNDED
GUARD RING
11.4
Timer1 Interrupt
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>).
11.5
Resetting Timer1 Using the CCP
Special Event Trigger
If the CCP module is configured in Compare mode
to
generate
a
Special
Event
Trigger
(CCP1M3:CCP1M0 = 1011), this signal will reset
Timer1. The trigger from CCP1 will also start an A/D
conversion if the A/D module is enabled (see
Section 13.3.4 “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.
11.6
Using Timer1 as a Real-Time
Clock
Adding an external LP oscillator to Timer1 (such as the
one described in Section 11.3 “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 11-1, 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 overflows.
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 error 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.
VDD
OSC1
VSS
OSC2
RC0
RC1
RC2
Note: Not drawn to scale.
Note:
The Special Event Triggers from the
CCP1 module will not set the TMR1IF
interrupt flag bit (PIR1<0>).
相关PDF资料
PDF描述
PIC18LF4320-I/PT IC MCU FLASH 4KX16 EEPROM 44TQFP
PIC18LF4321-I/ML IC PIC MCU FLASH 4KX16 44QFN
PIC18LF4431-I/ML IC PIC MCU FLASH 8KX16 44QFN
PIC18LF44J10-I/P IC PIC MCU FLASH 8KX16 40DIP
PIC18LF452-I/ML IC MCU FLASH 16KX16 A/D 44QFN
相关代理商/技术参数
参数描述
PIC18LF2455-I/SO 功能描述:8位微控制器 -MCU 24kBF 2048RM FSUSB2 RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
PIC18LF2455-I/SP 功能描述:8位微控制器 -MCU 24kBF 2048RM FSUSB2 RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
PIC18LF2455-I/SP 制造商:Microchip Technology Inc 功能描述:8 Bit Microcontroller Clock Speed:48MHz
PIC18LF2455T-I/SO 功能描述:8位微控制器 -MCU 24kBF 2048RM FSUSB2 RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
PIC18LF2458-I/SO 功能描述:8位微控制器 -MCU 24KB Flash 2KB RAM RoHS:否 制造商:Silicon Labs 核心:8051 处理器系列:C8051F39x 数据总线宽度:8 bit 最大时钟频率:50 MHz 程序存储器大小:16 KB 数据 RAM 大小:1 KB 片上 ADC:Yes 工作电源电压:1.8 V to 3.6 V 工作温度范围:- 40 C to + 105 C 封装 / 箱体:QFN-20 安装风格:SMD/SMT
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*