Intel 8051 manual ~ J -r-r ~r~ r =fJ

Page 12

8051 Architectural Specification and Functional Description

COUNTERI

GATETIMER

TIMERIRUN COUNTER

OIN MODE 3

~

G

Hn PULSE TO

SERIAL

PORT

COUNTER 1

MODE 0: 8-BIT TIMER WITH PRESCALERI 8-BIT COUNTER WITH PRESCALER-

MODE 1: 16-BIT TIMER/COUNTER

MODE 2: 8-BIT AUTO-RELOAD TIC

MODE 3: PREVENTS INCREMENTING OF TIC 1

INTERRUPT

REQUEST

J- ) -•

INT1

T1

--~ J >-r-r-

1"'"

~r~ - r - :=fJ--

 

XTAL1

+12

1-

~

 

COUNTER 0

 

-

"'

 

 

 

 

 

 

~

8-8ITTIMER

 

 

 

 

 

~

(THO)

 

 

 

Figure 2.5.8. Timer/Counter 1 Control and Status Flag Circuitry

• 100r11 Bit Frame

r - - - -- - - -- - -- - --- :;:R:;:;S; . - TT - ;; ----- l

•

Baud Rate Generetlon I

 

 

 

INTERRUPT

 

from Oscillator or

I

 

 

 

I -___-:-__ ~~~~SMIT

 

Timer 1

 

 

 

•

Address Frame

I

 

 

 

~-~-----~

 

Recognition

 

 

 

 

 

I

 

SCON

 

 

 

 

I

 

(SERIAL CONTROL)

 

 

 

 

 

 

 

 

 

 

I

 

CONTROL"

 

 

 

 

I

 

TIMING CIRCUITRY

 

 

 

 

 

 

 

 

 

g:~~~~t.,.OR- ....1

 

 

 

 

 

 

 

 

-:-16

 

 

 

TIMER 1

L ______________~~ ___ _

 

OVERFLOW

 

 

 

 

RECEIVER

 

 

 

 

 

 

RECEIVE

 

 

 

 

 

 

DATA

 

 

 

 

Figure 2.6. Serial Port~UART Modes 1, 2, and 3

2.1.2.4 SERIAL COMMUNICATIONS

 

 

The 8051 has a serial I/O port that is useful for serially

 

service the serial link. A block diagram of the serial port is

linking peripheral devices as well as multiple805ls

 

shown in Figure 2.6. Methods for linking UART (univer-

through standard asynchronous protocols with full-

 

sal asynchronous receiver / transmitter) devices are shown

duplex operatiori. The serial port also has a synchronous

 

in Figure 2.7 and a method for I/O expansion is shown in

mode for expansion of I/O lines using CMOS and TTL

 

Figure 2.8.

shift registers. This hardware serial communications

 

 

interface saves ROM code and permits a much higher

 

The full-duplex serial I/O port provides asynchronous

transmission rate

than could

be achieved through

o

modes to facilitate communications with standard UART

software. In response to a serial port interrupt request the

 

devices, such as printers and CRT terminals, or com-

CPU has only to read/write the serial port's buffer to

 

munications with other 8051s in multi-processor systems.

AFN-01488A-11

7

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Contents Architectural Specification ICE Architectural Specification and Functional Description SINGLE-COMPONENT 8-BIT MicrocomputerContents Architectural Overview Abstract Intelscomplete Line of SINGLE-CHIP MicrocomputersEnhancing the 8048 ARCHITEC- Ture for the 80s MACRO-VIEW of the 8051 Archi Tecture Architectural Speciffcation ancrFunctionaJ Descrlpfion On-Chip Peripheral Functions Request Microcomputer Expansion Components Ii~O,.R~~~~~~ ~ J -r-r ~r~ r =fJ Architectural Specification and Functional Description ~~~--------~--~--~---I~Instruction Decoder Program CounterInternal Data Memory · t1 Arithmetic Section ProgramControl SectionOscillator and Timing Circuitry Boolean ProcessorOperand Addressing Parallel I/O Ports~~143 136 ~ Data Manipulation Data Transfer OperationsLogic Operations 18. External Data Memory Move OperationsArithmetic Operations 21. Internal Data Memory Logic OperationsREGplSCTER 14e--I-~--I~IMMEDArE,.j Instruction SeT What the Instruction Set Is Organization of the Instruction SetData Transfer Control Transfer Operand Addressing Modes & Associated Operations 33.A Operand Addressing ModesInterrupt System MOVTFI TCON.7 Ports and I/O Pins External InterruptsAccessing External Memory TsU~l ArcnneCtural specification and Functional Description Accessing External Memory-Opera- tion of PortsAccessing External Memory-Bus Cycle Timing CDV TIMER/COUNTER Timer/Counter Mode SelectionConfiguring the Timer/Counter Input Serial Channel 47. Uart Interfacing Technique Operating Modes SCON.OUart Error Conditions Serial FrameTransmission Rate Generation Processor Reset and Initialization Power Down Standby Operation of Internal RAMEprom Programming Vee RSTNpD Instructions That Affect Flag Settings 8051 Instruction SET SummaryAll mnemonics copyrighted@ Intel Corporation
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