- 您现在的位置：买卖IC网 > Sheet目录3881 > PIC18F8720T-E/PT (Microchip Technology)IC PIC MCU FLASH 64KX16 80TQFP
PIC18F6520/8520/6620/8620/6720/8720
DS39609B-page 106
2004 Microchip Technology Inc.
10.2
PORTB, TRISB and LATB
Registers
PORTB is an 8-bit wide, bidirectional port. The corre-
sponding data direction register is TRISB. Setting a
TRISB bit (= 1) will make the corresponding PORTB
pin an input (i.e., put the corresponding output driver in
a high-impedance mode). Clearing a TRISB bit (= 0)
will make the corresponding PORTB pin an output (i.e.,
put the contents of the output latch on the selected pin).
The Data Latch register (LATB) is also memory
mapped. Read-modify-write operations on the LATB
register, read and write the latched output value for
PORTB.
EXAMPLE 10-2:
INITIALIZING PORTB
Each of the PORTB pins has a weak internal pull-up. A
single control bit can turn on all the pull-ups. This is
performed by clearing bit RBPU (INTCON2<7>). The
weak pull-up is automatically turned off when the port
pin is configured as an output. The pull-ups are
disabled on a Power-on Reset.
Four of the PORTB pins (RB3:RB0) are the external
interrupt pins, INT3 through INT0. In order to use these
pins as external interrupts, the corresponding TRISB
bit must be set to ‘1’.
The other four PORTB pins (RB7:RB4) have an inter-
rupt-on-change feature. Only pins configured as inputs
can cause this interrupt to occur (i.e., any RB7:RB4 pin
configured as an output is excluded from the interrupt-
on-change comparison). The input pins (of RB7:RB4)
are compared with the old value latched on the last
read of PORTB. The “mismatch” outputs of RB7:RB4
are OR’ed together to generate the RB Port Change
Interrupt with Flag bit, RBIF (INTCON<0>).
This interrupt can wake the device from Sleep. The
user, in the Interrupt Service Routine, can clear the
interrupt in the following manner:
a)
Any read or write of PORTB (except with the
MOVFF
instruction). This will end the mismatch
condition.
b)
Clear flag bit RBIF.
A mismatch condition will continue to set flag bit, RBIF.
Reading PORTB will end the mismatch condition and
allow flag bit RBIF to be cleared.
The interrupt-on-change feature is recommended for
wake-up on key depression operation and operations
where PORTB is only used for the interrupt-on-change
feature. Polling of PORTB is not recommended while
using the interrupt-on-change feature.
RB3 can be configured by the configuration bit
CCP2MX, as the alternate peripheral pin for the CCP2
module. This is only available when the device is
configured in Microprocessor, Microprocessor with
Boot Block, or Extended Microcontroller operating
modes.
The RB5 pin is used as the LVP programming pin.
When the LVP configuration bit is programmed, this pin
loses the I/O function and become a programming test
function.
FIGURE 10-5:
BLOCK DIAGRAM OF
RB7:RB4 PINS
Note:
On a Power-on Reset, these pins are
configured as digital inputs.
CLRF
PORTB
; Initialize PORTB by
; clearing output
; data latches
CLRF
LATB
; Alternate method
; to clear output
; data latches
MOVLW
0xCF
; Value used to
; initialize data
; direction
MOVWF
TRISB
; Set RB<3:0> as inputs
; RB<5:4> as outputs
; RB<7:6> as inputs
Note:
When LVP is enabled, the weak pull-up on
RB5 is disabled.
Data Latch
From other
RBPU(2)
P
VDD
I/O pin(1)
Q
D
CK
Q
D
CK
QD
EN
QD
EN
Data Bus
WR LATB
WR TRISB
Set RBIF
TRIS Latch
RD TRISB
RD PORTB
RB7:RB4 pins
Weak
Pull-up
RD PORTB
Latch
TTL
Input
Buffer
ST
Buffer
RB7:RB5 in Serial Programming Mode
Q3
Q1
RD LATB
or PORTB
Note 1:
I/O pins have diode protection to VDD and VSS.
2:
To enable weak pull-ups, set the appropriate TRIS bit(s)
and clear the RBPU bit (INTCON2<7>).
发布紧急采购，3分钟左右您将得到回复。
相关PDF资料
PIC18F4439T-E/ML
IC PIC MCU FLASH 6KX16 44QFN
XF2J-2824-11
CONN FPC 28POS 0.5MM SMT
PIC18F4439T-E/PT
IC PIC MCU FLASH 6KX16 44TQFP
PIC18F6585T-I/PT
IC PIC MCU FLASH 24KX16 64TQFP
PIC18LF8525T-I/PT
IC PIC MCU FLASH 24KX16 80TQFP
PIC18F6720T-E/PT
IC PIC MCU FLASH 64KX16 64TQFP
PIC18F4539T-E/PT
IC PIC MCU FLASH 12KX16 44TQFP
PIC16F685-I/P
IC PIC MCU FLASH 4KX14 20DIP
相关代理商/技术参数
PIC18F8720T-I/PT
功能描述:8位微控制器 -MCU 128KB 3840 RAM 68I/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
PIC18F8721-I/PT
功能描述:8位微控制器 -MCU 128kBF 4096RM 40MHz nonoWatt 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
PIC18F8721T-I/PT
功能描述:8位微控制器 -MCU 128kBF 4096RM 40MHz nonoWatt 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
PIC18F8722 DEVELOPMENT BOARD KIT
功能描述:DEVELOPMENT BOARD FOR PIC18F8722 RoHS:否 类别:编程器，开发系统 >> 通用嵌入式开发板和套件（MCU、DSP、FPGA、CPLD等） 系列:- 标准包装:1 系列:PICDEM™ 类型:MCU 适用于相关产品:PIC10F206，PIC16F690，PIC16F819 所含物品:板，线缆，元件，CD，PICkit 编程器 产品目录页面:659 (CN2011-ZH PDF)
PIC18F8722 DEVELOPMENT KIT
功能描述:EMBEDDED C DEVELOPMENT KIT RoHS:否 类别:编程器，开发系统 >> 通用嵌入式开发板和套件（MCU、DSP、FPGA、CPLD等） 系列:PIC® 产品培训模块:Blackfin® Processor Core Architecture Overview
Blackfin® Device Drivers
Blackfin® Optimizations for Performance and Power Consumption
Blackfin® System Services 特色产品:Blackfin? BF50x Series Processors 标准包装:1 系列:Blackfin® 类型:DSP 适用于相关产品:ADSP-BF548 所含物品:板，软件，4x4 键盘，光学拨轮，QVGA 触摸屏 LCD 和 40G 硬盘 配用:ADZS-BFBLUET-EZEXT-ND - EZ-EXTENDER DAUGHTERBOARDADZS-BFLLCD-EZEXT-ND - BOARD EXT LANDSCAP LCD INTERFACE 相关产品:ADSP-BF542BBCZ-4A-ND - IC DSP 16BIT 400MHZ 400CSBGAADSP-BF544MBBCZ-5M-ND - IC DSP 16BIT 533MHZ MDDR 400CBGAADSP-BF542MBBCZ-5M-ND - IC DSP 16BIT 533MHZ MDDR 400CBGAADSP-BF542KBCZ-6A-ND - IC DSP 16BIT 600MHZ 400CSBGAADSP-BF547MBBCZ-5M-ND - IC DSP 16BIT 533MHZ MDDR 400CBGAADSP-BF548BBCZ-5A-ND - IC DSP 16BIT 533MHZ 400CSBGAADSP-BF547BBCZ-5A-ND - IC DSP 16BIT 533MHZ 400CSBGAADSP-BF544BBCZ-5A-ND - IC DSP 16BIT 533MHZ 400CSBGAADSP-BF542BBCZ-5A-ND - IC DSP 16BIT 533MHZ 400CSBGA
PIC18F8722-E/PT
功能描述:8位微控制器 -MCU 128 KB FL 3936 RAM 25 MHz 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
PIC18F8722-I/PT
功能描述:8位微控制器 -MCU 128 KB FL 4K RAM 70 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
PIC18F8722T-E/PT
功能描述:8位微控制器 -MCU 128 KB FL 3936 RAM 25MHz 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