PIC16C432-E/P (Microchip) PDF资料下载 Datasheet(15/70 页)

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参数资料

型号：	PIC16C432-E/P
厂商：	Microchip Technology
文件页数：	15/70页
文件大小：	0K
描述：	IC MCU CMOS 8-BIT 20MHZ 2K 20DIP
标准包装：	25
系列：	PIC® 16C
核心处理器：	PIC
芯体尺寸：	8-位
速度：	20MHz
连通性：	LIN（本地互连网络）
外围设备：	欠压检测/复位，POR，WDT
输入/输出数：	12
程序存储器容量：	3.5KB（2K x 14）
程序存储器类型：	OTP
RAM 容量：	128 x 8
电压 - 电源 (Vcc/Vdd)：	4.5 V ~ 5.5 V
振荡器型：	外部
工作温度：	-40°C ~ 125°C
封装/外壳：	20-DIP（0.300"，7.62mm）
包装：	管件
配用：	AC164029-ND - MODULE SKT PROMATEII 20DIP/SSOP DVA16XP201-ND - ADAPTER DEVICE FOR MPLAB-ICE

PIC16C432

DS41140B-page 20

Preliminary

2002 Microchip Technology Inc.

4.2

PORTB and TRISB Registers

PORTB is an 8-bit wide, bi-directional port. The

corresponding data direction register is TRISB. A ’1’ in

the TRISB register puts the corresponding output driver

in a High Impedance mode. A ’0’ in the TRISB register

puts the contents of the output latch on the selected

pin(s).

Reading PORTB register reads the status of the pins,

whereas writing to it will write to the port latch. All write

operations are read-modify-write operations. So a write

to a port implies that the port pins are first read, then

this value is modified and written to the port data latch.

Each of the PORTB pins has a weak internal pull-up

(

≈200 A typical). A single control bit can turn on all the

pull-ups.

This

done

clearing

the

RBPU

(OPTION<7>) bit. The weak pull-up is automatically

turned off when the port pin is configured as an output.

The pull-ups are disabled on Power-on Reset.

Four of PORTB’s pins, RB<7:4>, have an interrupt-on-

change feature. Only pins configured as inputs can

cause this interrupt to occur (i.e., any RB<7:4> pin con-

figured as an output is excluded from the interrupt-on-

change comparison). The input pins of RB<7:4> are

compared with the old value latched on the last read of

PORTB. The “mismatch” outputs of RB<7:4> are

OR’ed together to generate the RBIF interrupt (flag

latched in INTCON<0>).

FIGURE 4-5:

BLOCK DIAGRAM OF

RB<7:4> PINS

This interrupt can wake the device from SLEEP. The

user, in the Interrupt Service Routine, can clear the

interrupt in the following manner:

Any read or write of PORTB. This will end the

mismatch condition.

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.

This interrupt-on-mismatch feature, together with

software configurable pull-ups on these four pins, allow

easy interface to a key pad and make it possible for

wake-up on key depression. (See AN552, “Implement-

ing Wake-up on Key Strokes”.)

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.

FIGURE 4-6:

BLOCK DIAGRAM OF

RB<3:0> PINS

Data Latch

From other

RBPU(1)

VDD

I/O pin

Data Bus

WR PORTB

WR TRISB(1)

Set RBIF

TRIS Latch

RD TRISB

RD PORTB

RB<7:4> pins

Weak

Pull-up

RD Port

Latch

TTL

Input

Buffer

RB<7:6> in Serial Programming mode

Note

TRISB = 1 enables weak pull-up if RBPU = 0

(OPTION<7>).

Note:

If a change on the I/O pin should occur

when the read operation is being executed

(start of the Q2 cycle), then the RBIF inter-

rupt flag may not get set.