參數(shù)資料
型號： PIC16C715
廠商： Microchip Technology Inc.
英文描述： 8-Bit CMOS Microcontroller with A/D Converter(每個I/O口有25mA驅(qū)動/吸收電流，微控制器)
中文描述： 8位CMOS微控制器與A / D轉(zhuǎn)換器（每個的I / O口有25毫安驅(qū)動/吸收電流，微控制器）
文件頁數(shù)： 27/120頁
文件大小： 764K
代理商： PIC16C715
1996 Microchip Technology Inc.
Advance Information
DS30560A-page 27
PIC16C715
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
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
of PORTB will cause all eight bits of PORTB to be read
into the CPU. Then the
BSF
bit5 and PORTB is written to the output latches. If
another bit of PORTB is used as a bi-directional I/O pin
(e.g., bit0) 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 bit0 is switched to an output, the content of the data
latch may now be unknown.
Reading the 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 5-3 shows the effect of two sequential read-
modify-write instructions on an I/O port.
BCF
and
BSF
BSF
operation on bit5
operation takes place on
EXAMPLE 5-3:
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-ups and are
;not connected to other circuitry
;
; PORT latch PORT pins
; ---------- ---------
BCF PORTB, 7 ; 01pp pppp 11pp pppp
BCF PORTB, 6 ; 10pp 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 ppp. The 2nd BCF
;caused RB7 to be latched as the pin value
;(high).
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.
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 5-5). 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 depen-
dent) 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
instruction not accessing this I/O port.
NOP
or another
FIGURE 5-5:
SUCCESSIVE I/O OPERATION
PC
PC + 1
PC + 2
PC + 3
Q1
Q2
Q3 Q4
Q1
Q2
Q3 Q4 Q1
Q2
Q3 Q4
Q1
Q2
Q3 Q4
InstructPC
fetched
RB7:RB0
MOVWF PORTB
write to
PORTB
NOP
Port pin
sampled here
NOP
MOVF PORTB,W
Instruction
executed
MOVWF PORTB
write to
PORTB
NOP
MOVF PORTB,W
T
PD
Note:
This example shows a write to PORTB
followed by a read from PORTB.
Note that:
data setup time = (0.25T
CY
- T
PD
)
where T
CY
= instruction cycle
T
PD
= propagation delay
Therefore, at higher clock frequencies,
a write followed by a read may be prob-
lematic.
相關(guān)PDF資料
PDF描述
PIC16C717 8-Bit CMOS Microcontrollers(8位CMOS微控制器)
PIC16C770 8-Bit CMOS Microcontrollers(8位CMOS微控制器)
PIC16C771 8-Bit CMOS Microcontrollers(8位CMOS微控制器)
PIC16C73A 8-Bit CMOS Microcontrollers with A/D Converter
PIC16C76 8-Bit CMOS Microcontrollers with A/D Converter(每個I/O口有25mA驅(qū)動/吸收電流,并行從動口,2路捕捉/比較/PWM的微控制器)
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
PIC16C715/JW 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 13 I/O 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
PIC16C715-04/P 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 13 I/O 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
PIC16C715-04/P 制造商:Microchip Technology Inc 功能描述:IC 8BIT CMOS MCU 16C715 DIP18
PIC16C715-04/P 制造商:Microchip Technology Inc 功能描述:Microcontroller IC Number of I/Os:13
PIC16C715-04/SO 功能描述:8位微控制器 -MCU 3.5KB 128 RAM 13 I/O 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
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。

采購需求

(若只采購一條型號，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

*型號 *數(shù)量 廠商 批號 封裝
添加更多采購

我的聯(lián)系方式

*
*
*