參數(shù)資料
型號： PIC16F627-20E/P
廠商： Microchip Technology
文件頁數(shù)： 110/170頁
文件大?。?/td> 0K
描述： IC MCU FLASH 1KX14 18-DIP
標(biāo)準(zhǔn)包裝： 25
系列： PIC® 16F
核心處理器： PIC
芯體尺寸： 8-位
速度： 20MHz
連通性： UART/USART
外圍設(shè)備： 欠壓檢測/復(fù)位，POR，PWM，WDT
輸入/輸出數(shù)： 16
程序存儲器容量： 1.75KB（1K x 14）
程序存儲器類型： 閃存
EEPROM 大?。?/td> 128 x 8
RAM 容量： 224 x 8
電壓 - 電源 (Vcc/Vdd)： 3 V ~ 5.5 V
振蕩器型： 內(nèi)部
工作溫度： -40°C ~ 125°C
封裝/外殼： 18-DIP（0.300"，7.62mm）
包裝： 管件
配用： DVA16XP183-ND - ADAPTER ICE 18DIP/SOIC/SSOP
PIC16F62X
DS40300C-page 42
Preliminary
2003 Microchip Technology Inc.
5.3
I/O Programming Considerations
5.3.1
BI-DIRECTIONAL I/O PORTS
Any instruction which writes, operates internally as a
read followed by a write operation. The BCF and BSF
instructions, for example, read the register into the
CPU, execute the bit operation and write the result
back to the register. Caution must be used when these
instructions are applied to a port with both inputs and
outputs defined. For example, a BSF operation on Bit 5
of PORTB will cause all eight bits of PORTB to be read
into the CPU. Then the BSF operation takes place on
Bit 5 and PORTB is written to the output latches. If
another bit of PORTB is used as a bi-directional I/O pin
(e.g., Bit 0) and it is defined as an input at this time, the
input signal present on the pin itself would be read into
the CPU and rewritten to the data latch of this particular
pin, overwriting the previous content. As long as the pin
stays in the Input mode, no problem occurs. However,
if Bit 0 is switched into Output mode later on, the
content of the data latch may now be unknown.
Reading a port register, reads the values of the port
pins. Writing to the port register writes the value to the
port latch. When using read-modify-write instructions
(ex. BCF, BSF, etc.) on a port, the value of the port pins
is read, the desired operation is done to this value, and
this value is then written to the port latch.
Example 5-2 shows the effect of two sequential read-
modify-write instructions (ex., BCF, BSF, etc.) on an
I/O port.
A pin actively outputting a Low or High should not be
driven from external devices at the same time in order
to change the level on this pin (“wired-or”, “wired-and”).
The resulting high output currents may damage
the chip.
EXAMPLE 5-2:
READ-MODIFY-WRITE
INSTRUCTIONS ON AN
I/O PORT
;Initial PORT settings:PORTB<7:4> Inputs
;
PORTB<3:0> Outputs
;PORTB<7:6> have external pull-up and are not
;connected to other circuitry
;
PORT latchPORT Pins
---------- ----------
BCF STATUS, RP0
;
BCF PORTB, 7
;01pp pppp 11pp pppp
BSF STATUS, RP0
;
BCF TRISB, 7
;10pp pppp 11pp pppp
BCF TRISB, 6
;10pp pppp 10pp pppp
;
;Note that the user may have expected the pin
;values to be 00pp pppp. The 2nd BCF caused
;RB7 to be latched as the pin value (High).
5.3.2
SUCCESSIVE OPERATIONS ON I/O
PORTS
The actual write to an I/O port happens at the end of an
instruction cycle, whereas for reading, the data must be
valid at the beginning of the instruction cycle (Figure 5-
16). Therefore, care must be exercised if a write
followed by a read operation is carried out on the same
I/O port. The sequence of instructions should be such
to allow the pin voltage to stabilize (load dependent)
before the next instruction which causes that file to be
read into the CPU is executed. Otherwise, the previous
state of that pin may be read into the CPU rather than
the new state. When in doubt, it is better to separate
these instructions with a NOP or another instruction not
accessing this I/O port.
FIGURE 5-16:
SUCCESSIVE I/O OPERATION
Q1
Q2 Q3 Q4
PC
Instruction
fetched
Q1
Q2 Q3 Q4
Q1
Q2 Q3 Q4 Q1
Q2 Q3 Q4
PC + 1
PC
PC + 2
PC + 3
MOWF
PORTB
Write to PORTB
MOWF
PORTB, W
Read to PORTB
NOP
T
PD
Execute
MOVWF
PORTB
Execute
MOVWF
PORTB
Port pin
sampled here
Execute
NOP
Note
1: This example shows write to PORTB followed by a read from PORTB.
2: Data setup time = (0.25 TCY - TPD) where TCY = instruction cycle and TPD = propagation delay of Q1 cycle to output valid.
Therefore, at higher clock frequencies, a write followed by a read may be problematic.
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
PIC16F627-20I/P 功能描述:8位微控制器 -MCU 1.75KB 224 RAM 16I/O 20MHz IndTemp PDIP18 RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
PIC16F627-20I/P 制造商:Microchip Technology Inc 功能描述:IC 8BIT FLASH MCU 16F627 DIP18
PIC16F627-20I/SO 功能描述:8位微控制器 -MCU 1.75KB 224 RAM 16I/O 20MHz IndTemp SOIC18 RoHS:否 制造商:Silicon Labs 核心:8051 處理器系列:C8051F39x 數(shù)據(jù)總線寬度:8 bit 最大時鐘頻率:50 MHz 程序存儲器大小:16 KB 數(shù)據(jù) RAM 大小:1 KB 片上 ADC:Yes 工作電源電壓:1.8 V to 3.6 V 工作溫度范圍:- 40 C to + 105 C 封裝 / 箱體:QFN-20 安裝風(fēng)格:SMD/SMT
PIC16F627-20I/SO 制造商:Microchip Technology Inc 功能描述:8BIT FLASH MCU SMD 16F627 SOIC18
PIC16F627-20I/SO 制造商:Microchip Technology Inc 功能描述:Microcontroller IC Number of I/Os:16
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