Transcript MICROPROCESSOR AND INTERFACING

MICROPROCESSOR AND
INTERFACING
AUTHORS
:RAMESH.S.GAONKAR
BADRI RAM
DOUGLAS.V.HALL
LIU AND GIBSON
Syllabus of Microprocessor








Introduction to microprocessor
Architecture and block diagram of microprocessor
8085 microprocesso
8237 DMA Controller
8255 Programmable peripheral interface device
8254 programmable interval timer
8259 programmable inttrupt controller
8086 microprocessor
What is Microprocessor?
A silicon chip that contains a CPU. In the world
of personal computers, the terms
microprocessor and CPU are used
interchangeably. At the heart of all personal
computers and most workstations sits a
microprocessor. Microprocessors also control
the logic of almost all digital devices, from
clock radios to fuel-injection systems for
automobiles
Microprocessor def.. Con..




Microprocessor is a programmable device
It can be instructed to perform given tasks
with in its capability.
The programmer selects instruction from the
list and determines the sequence of
execution for a given task.
It takes input from the input device and
process the input as it behaves like a CPU
and gives the output.
Microprocessor def.. Con..





Microprocessor is a clock driven
semiconductor device consisting of electronic
logic circuits manufactured by using a LSI or
VLSI technique.
Microprocessor can be divided into three
segments
1)ALU
2)Register array
3)Control unit
Block diagram of microprocessor
INPUT
Microprocessor
As
CPU
MEMORY
OUTPUT
Characterstics which differentiate
microprocessors



Instruction set: The set of instructions that
the microprocessor can execute.
bandwidth : The number of bits processed
in a single instruction.
clock speed : Given in megahertz (MHz),
the clock speed determines how many
instructions per second the processor can
execute.
Structure of microprocessor

Chip containing no. of elements for the
processing purposes.
History of microprocessor

Intel's 4004 is considered the first
microprocesor .

The 4004 was later followed in 1972 by the
8008, the world's first 8-bit microprocessor.
History of microprocessor……

then is the 8080 microprocessor evolved in
1974.

Then comes 8085 that is the 8 bit
microprocessor
Continued…


Often the processor is required to manage various
different tasks that have to be scheduled somehow
and must also deal with outside interrupt sources
such as an alarm when something goes wrong.
Real-time systems are those in which timeliness is
as important as the correctness of the outputs,
although this does NOT mean that they have to be
?fast systems?.
–
A real-time system does not have to process data in
microseconds to be considered real-time - it must simply
have response times that are constrained and thus
predictable.
Real life applications of
microprocessor


Microprocessors are used to handle a set of tasks that control
one or more external events or systems.
Microprocessors are typically used in either reactive or
embedded systems.
–
–
Reactive systems are those that have an ongoing interaction with
their environment - for example, a fire-control system that
constantly reacts to buttons pressed by a pilot.
Embedded systems are those used to control specialized
hardware in which the computer system is installed - for example,
the microprocessor system used to control the fuel/air mixture in
the carburetor of many automobiles.

In embedded systems the software system is completely
encapsulated by the hardware that it controls.
Some questions





What is SSI,MSI and LSI?
What is difference between microprocessor,
microcontroller and microcomputer?
What is a bit, byte, nibble and a word?
What is difference between compiler and
interpreter?
What is instruction and mnemonic?
8085 programming model






Program counter
Stack pointer
General purpose registers
Accumulator
Flag registers
Data and address buses
8085 instruction set





Data transfer operations
Arithmetic operations
Logical operations
Branch operations
Machine control operations
Data transfer operations






MOV Rd,Rs
MVI R,8 bit
HLT
IN 8 bit port address accept the data from the
input port specified in the second byte and loads into
the accumulator.
NOP
OUT 8 bit port address copies the contents of the
accumulator to the output port specified in the
second byte,2 byte instruction
Data transfer operations




This group of instructions copies data from a
location called a source to another a location
called destination without modifying the
contents of the source.
Data transfer can be between 1)registers
Specified data byte to a register or memory
location
Between a memory location and a register
Addressing mode




Immediate addressing mvi
Register addressing mov
Direct addressing in/out ports
Indirect addressing
Logical operations







ANA R
ANI 8 bit
ORA R
ORI 8 bit
XRA R
XRI 8 bit
CMA
Arthimetic operations






ADD R
ADI 8 bit
SUB R
SUI 8 bit
INR R
DCR R
Branch operations








JMP 16 bit 2nd(low) and 3rd(high) byte specifies 16 bit
Memory address
JC
JNC
JZ
JNZ
JP
JM
Microprocessor architecture

The process of data manipulation and
communication is determined by the logic
design of the microprocessor called the
arcitecture.
Microprocessor architecture
Microprocessor initiated operations
 Internal operations
Externally initiated operations

To perform these functions microprocessor
requires a group of logic circuits and set of
signals called control signals.
Microprocessor initiated operations




Memory read
Memory write
I/O read
I/O write
Internal operations





Store 8-bit data
Perform arthimetic and logical operations
Test for conditions
Sequence the excuetion of operations
Store data temporarily during excuetion
8085 pin diagram
Is 8 bit microprocessor, capable of addressing
64k of memory
Has 40 pins ,operate with 3mhz single phase
clock
Require +5v of single power supply
8085 pin diagram
8085 pin diagram
Is 8 bit microprocessor, capable of addressing
64k of memory
Has 40 pins ,operate with 3mhz single phase
clock
Require +5v of single power supply
Pin diagram conti….







All the signals are classified into 6 groups
Address bus
Data bus
Control and status signals
Power supply and frequency signals
Externally initiated signals
Serial input output ports
Block diagram of 8085 microprocessor







It includes
Arithmetic and logic unit
Timing and control unit
Instruction register and decoder
Register array
Interrupt control
Serial input output control
8085 interrupt





What is interrupt?
Vectored interrupt
Non vectored interrupt
Enable and disable interrupt instructions
Pending interrupts
8085 interrupt

Interrupt is a process where an external device can get the
attention of the microprocessor.
–
–

The process starts from the I/O device
The process is asynchronous.
Classification of Interrupts
–
Interrupts can be classified into two types:



Maskable Interrupts (Can be delayed or Rejected)
Non-Maskable Interrupts (Can not be delayed or Rejected)
Interrupts can also be classified into:


Vectored (the address of the service routine is hard-wired)
Non-vectored (the address of the service routine needs to be supplied
externally by the device)
Interrupts

An interrupt is considered to be an emergency signal
that may be serviced.
–

The Microprocessor may respond to it as soon as possible.
What happens when MP is interrupted ?
–
–
When the Microprocessor receives an interrupt signal, it
suspends the currently executing program and jumps to an
Interrupt Service Routine (ISR) to respond to the incoming
interrupt.
Each interrupt will most probably have its own ISR.
Interrupts




When a device interrupts, it actually wants the MP to
give a service which is equivalent to asking the MP
to call a subroutine. This subroutine is called ISR
(Interrupt Service Routine)
The ‘EI’ instruction is a one byte instruction and is
used to Enable the non-maskable interrupts.
The ‘DI’ instruction is a one byte instruction and is
used to Disable the non-maskable interrupts.
The 8085 has a single Non-Maskable interrupt.
–
The non-maskable interrupt is not affected by the value of
the Interrupt Enable flip flop.
8085 intrrupts






TRAP
RST7.5
RST6.5
RST 5.5
INTR
INTA
Interrupt Vectors and the Vector
Table


An interrupt vector is a pointer to where the
ISR is stored in memory.
All interrupts (vectored or otherwise) are
mapped onto a memory area called the
Interrupt Vector Table (IVT).
–
–
The IVT is usually located in memory page 00
(0000H - 00FFH).
The purpose of the IVT is to hold the vectors that
redirect the microprocessor to the right place
when an interrupt arrives.
GENERAL PURPOSE
PROGRAMMABLE PERIPHERAL
DEVICES





8255A Programmable peripheral interface
8254 programmable interval timer
8259 Programmable interval timer
8237 DMA Controller
8255 Programmable peripheral
interface





It can be programmed to transfer data under
various conditions.
It has 24 I/O pins.
The function of 8255A classified acc to two
modes.
A) BSR mode
I/O mode
8255 Programmable peripheral
interface






Block diagram of 8255A
Control word
BSR mode
Mode 0
Mode 1
Mode 2
Control Word
 D7 D6 D5 D4 D3 D2 D1 D0
0/1
BSR Mode
I/O Mode
For port C
Mode0 Mode 1 Mode2
No effect on mode
Simple I/O
Handshake I/O

for ports
A,B,C

for ports A and or B
Port C bits
8254 Programmable interval timer
8237 DMA Controller





DMA is an input output technique used for
high speed data transfer
Data transfer between system memory and
floppy disk
It introduces two new signals that are
HOLD
HLDA
DMA Controller cont….







DMA Controller consists of
DMA channels and interfacing
DMA Signals
System interface
Programming the 8237
DMA Execution consists of
Master and slave mode
8086 microprocessor





It is 16 bit microprocessor.
Contains 29000 transistors and is fabricated
using HMOS technology.
Has addressing capacity of I megabyte.
Has 20 address pins.
+5v supply voltage
8086 Arcitecture







Internal registers
Control logic
Instruction queue
ALU
PSW
Pointers
Segment registers
8086 pin diagram
8086 effective address computations

To provide flexible base addressing and
indexing a data address may be formed by
addressing together a combination of the BX
or BP register contents SI or DI contents and
a displacement.The result of such and
address computation is called effective
address.
8086 memory segmentation

Address within segments

Overlapping segments
Program relocation using CS register

If a programmer wants to relocate the
program by any means ,he can relocate the
program using cs register.