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参数资料
型号： PIC18F452-I/PT
厂商： Microchip Technology
文件页数： 84/134页
文件大小： 0K
描述： IC MCU FLASH 16KX16 EE 44TQFP
产品培训模块： Asynchronous Stimulus
8-bit PIC® Microcontroller Portfolio
标准包装： 160
系列： PIC® 18F
核心处理器： PIC
芯体尺寸： 8-位
速度： 40MHz
连通性： I²C，SPI，UART/USART
外围设备： 欠压检测/复位，LVD，POR，PWM，WDT
输入/输出数： 34
程序存储器容量： 32KB（16K x 16）
程序存储器类型： 闪存
EEPROM 大小： 256 x 8
RAM 容量： 1.5K x 8
电压 - 电源 (Vcc/Vdd)： 4.2 V ~ 5.5 V
数据转换器： A/D 8x10b
振荡器型： 外部
工作温度： -40°C ~ 85°C
封装/外壳： 44-TQFP
包装： 托盘
配用： XLT44PT3-ND - SOCKET TRAN ICE 44MQFP/TQFP
AC164305-ND - MODULE SKT FOR PM3 44TQFP
444-1001-ND - DEMO BOARD FOR PICMICRO MCU
AC164020-ND - MODULE SKT PROMATEII 44TQFP
1997 Microchip Technology Inc.
DS30444E - page 53
PIC16C9XX
8.3
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 overow which will wake-up
the processor. However, special precautions in soft-
ware are needed to read-from or write-to the Timer1
register pair (TMR1H:TMR1L) (Section 8.3.2).
In asynchronous counter mode, Timer1 cannot be used
as a time-base for capture or compare operations.
8.3.1
EXTERNAL CLOCK INPUT TIMING WITH
UNSYNCHRONIZED CLOCK
If control bit T1SYNC is set, the timer will increment
completely asynchronously. The input clock must meet
certain minimum high time and low time requirements,
as specied in timing parameters 45, 46, and 47.
8.3.2
READING AND WRITING TMR1 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 overow 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 unpre-
dictable value in the timer register.
Reading
the
16-bit
value
requires
some
care.
Example 8-1 is an example routine to read the 16-bit
timer value. This is useful if the timer cannot be
stopped.
EXAMPLE 8-1:
READING A 16-BIT
FREE-RUNNING TIMER
; All interrupts are disabled
MOVF
TMR1H, W
;Read high byte
MOVWF
TMPH
;
MOVF
TMR1L, W
;Read low byte
MOVWF
TMPL
;
MOVF
TMR1H, W
;Read high byte
SUBWF
TMPH,
W
;Sub 1st read
; with 2nd read
BTFSC
STATUS,Z
;Is result = 0
GOTO
CONTINUE
;Good 16-bit read
;
; TMR1L may have rolled over between the read
; of the high and low bytes. Reading the high
; and low bytes now will read a good value.
;
MOVF
TMR1H, W
;Read high byte
MOVWF
TMPH
;
MOVF
TMR1L, W
;Read low byte
MOVWF
TMPL
;
; Re-enable the Interrupt (if required)
CONTINUE
;Continue with your code
8.4
Timer1 Oscillator
A crystal oscillator circuit is built in between pins T1OSI
(input) and T1OSO (amplier output). It is enabled by
setting control bit T1OSCEN (T1CON<3>). The oscilla-
tor is a low power oscillator rated up to 200 kHz. It will
continue to run during SLEEP. It is primarily intended
for a 32 kHz crystal. Table 8-1 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 8-1: CAPACITOR SELECTION FOR
THE TIMER1 OSCILLATOR
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 appropri-
ate values of external components.
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PIC18F452T-E/ML 功能描述:8位微控制器 -MCU 40MHz 16KB Flash 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
PIC18F452T-I/L 功能描述:8位微控制器 -MCU 32KB 1536 RAM 34I/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
PIC18F452T-I/ML 功能描述:8位微控制器 -MCU 32KB 1536 RAM 34I/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
PIC18F452T-I/PT 功能描述:8位微控制器 -MCU 32KB 1536 RAM 34I/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
PIC18F452T-I/PTG 功能描述:8位微控制器 -MCU 32KB 1536 RAM 34I/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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