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参数资料
型号： PIC16F871T-E/L
厂商： Microchip Technology
文件页数： 93/143页
文件大小： 0K
描述： IC MCU CMOS 20MHZ 2K FLSH 44PLCC
标准包装： 500
系列： PIC® 16F
核心处理器： PIC
芯体尺寸： 8-位
速度： 20MHz
连通性： UART/USART
外围设备： 欠压检测/复位，POR，PWM，WDT
输入/输出数： 33
程序存储器容量： 3.5KB（2K x 14）
程序存储器类型： 闪存
EEPROM 大小： 64 x 8
RAM 容量： 128 x 8
电压 - 电源 (Vcc/Vdd)： 4 V ~ 5.5 V
数据转换器： A/D 8x10b
振荡器型： 外部
工作温度： -40°C ~ 125°C
封装/外壳： 44-LCC（J 形引线）
包装： 带卷 (TR)
2003 Microchip Technology Inc.
DS30569B-page 51
PIC16F870/871
6.4
Timer1 Operation in
Asynchronous Counter Mode
If control bit T1SYNC (T1CON<2>) is set, the external
clock input is not synchronized. The timer continues to
increment asynchronous to the internal phase clocks.
The timer will continue to run during SLEEP and can
generate an interrupt-on-overflow, which will wake-up
the
processor.
However,
special
precautions
in
software
are
needed
to
read/write
the
timer
(Section 6.4.1).
In Asynchronous Counter mode, Timer1 cannot be
used as a time base for capture or compare operations.
6.4.1
READING AND WRITING TIMER1 IN
ASYNCHRONOUS COUNTER
MODE
Reading TMR1H or TMR1L while the timer is running
from an external asynchronous clock, will ensure a
valid read (taken care of in hardware). However, the
user should keep in mind that reading the 16-bit timer
in two 8-bit values itself, poses certain problems, since
the timer may overflow between the reads.
For writes, it is recommended that the user simply stop
the timer and write the desired values. A write conten-
tion may occur by writing to the timer registers, while
the register is incrementing. This may produce an
unpredictable value in the timer register.
Reading
the
16-bit
value
requires
some
care.
Examples 12-2 and 12-3 in the PICmicro Mid-Range
MCU Family Reference Manual (DS33023) show how
to read and write Timer1 when it is running in
Asynchronous mode.
6.5
Timer1 Oscillator
A crystal oscillator circuit is built-in between pins T1OSI
(input) and T1OSO (amplifier output). It is enabled by
setting control bit, T1OSCEN (T1CON<3>). The oscil-
lator is a low power oscillator, rated up to 200 kHz. It will
continue to run during SLEEP. It is primarily intended
for use with a 32 kHz crystal. Table 6-1 shows the
capacitor selection for the Timer1 oscillator.
The Timer1 oscillator is identical to the LP oscillator.
The user must provide a software time delay to ensure
proper oscillator start-up.
TABLE 6-1:
CAPACITOR SELECTION FOR
THE TIMER1 OSCILLATOR
6.6
Resetting Timer1 Using a CCP
Trigger Output
If the CCP1 module is configured in Compare mode to
generate a “special event trigger” (CCP1M3:CCP1M0
= 1011), this signal will reset Timer1.
Timer1 must be configured for either Timer or Synchro-
nized Counter mode to take advantage of this feature.
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 from CCP1, the write will take
precedence.
In this mode of operation, the CCPRH:CCPRL register
pair effectively becomes the period register for Timer1.
Osc Type
Freq.
C1
C2
LP
32 kHz
33 pF
100 kHz
15 pF
200 kHz
15 pF
These values are for design guidance only.
Crystals Tested:
32.768 kHz
Epson C-001R32.768K-A
± 20 PPM
100 kHz
Epson C-2 100.00 KC-P
± 20 PPM
200 kHz
STD XTL 200.000 kHz
± 20 PPM
Note 1:
Higher capacitance increases the stability
of oscillator, but also increases the start-up
time.
2:
Since each resonator/crystal has its own
characteristics, the user should consult the
resonator/crystal manufacturer for
appropriate values of external components.
Note:
The special event triggers from the CCP1
module will not set interrupt flag bit
TMR1IF (PIR1<0>).
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相关代理商/技术参数
参数描述
PIC16F871T-I/L 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 33 I/O 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
PIC16F871T-I/PT 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 33 I/O 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
PIC16F872-E/SO 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 22 I/O 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
PIC16F872-E/SOVAO 制造商:Microchip Technology Inc 功能描述:
PIC16F872-E/SP 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 22 I/O 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
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