参数资料
型号: PIC17CXX
厂商: Microchip Technology Inc.
英文描述: EPROM Memory Programming Specification
中文描述: EPROM存储器编程规范
文件页数: 57/71页
文件大小: 1173K
代理商: PIC17CXX
PIC17C4X
DS30412C-page 60
1996 Microchip Technology Inc.
9.4
PORTD and DDRD Registers
PORTD is an 8-bit bi-directional port. The correspond-
ing data direction register is DDRD. A '1' in DDRD con-
gures the corresponding port pin as an input. A '0' in
the DDRC register congures the corresponding port
pin as an output. Reading PORTD reads the status of
the pins, whereas writing to it will write to the port latch.
PORTD is multiplexed with the system bus. When
operating as the system bus, PORTD is the high order
byte of the address/data bus (AD15:AD8). The timing
for the system bus is shown in the Electrical Character-
istics section.
Note:
This port is congured as the system bus
when the device’s conguration bits are
selected to Microprocessor or Extended
Microcontroller modes. In the two other
microcontroller modes, this port is a gen-
eral purpose I/O.
Example 9-3 shows the instruction sequence to initial-
ize PORTD. The Bank Select Register (BSR) must be
selected to Bank 1 for the port to be initialized.
EXAMPLE 9-3:
INITIALIZING PORTD
MOVLB
1
;
Select Bank 1
CLRF
PORTD
;
Initialize PORTD data
;
latches before setting
;
the data direction
;
register
MOVLW
0xCF
;
Value used to initialize
;
data direction
MOVWF
DDRD
;
Set RD<3:0> as inputs
;
RD<5:4> as outputs
;
RD<7:6> as inputs
FIGURE 9-7:
PORTD BLOCK DIAGRAM (IN I/O PORT MODE)
Note: I/O pins have protection diodes to VDD and Vss.
Q
D
CK
TTL
0
1
Q
D
CK
R
S
Input
Buffer
Port
Data
to D_Bus
→ IR
INSTRUCTION READ
Data Bus
RD_PORTD
WR_PORTD
RD_DDRD
WR_DDRD
EX_EN
DATA/ADDR_OUT
DRV_SYS
SYS BUS
Control
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PIC17LC42A-08/P 功能描述:8位微控制器 -MCU 4KB 232 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
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