E-m--be-dde-d -sy-s-te---m_Day_1_ES.pptx

INTRODUCTION TO
EMBEDDED SYSTEMS

What is a System
 A system is a way of working, organizing or doing one or
many tasks according to a fixed plan, program or set of
rules.
 A system is also an arrangement in which all its units
assemble and work together according to the plan or
program.

SYSTEM EXAMPLES
WATCH
It is a time display SYSTEM
Parts: Hardware, Needles, Battery, Dial, Chassis and Strap
Rules
 All needles move clockwise only
 A thin needle rotates every second
 A long needle rotates every minute
 A short needle rotates every hour
 All needles return to the original position after 12
hours

SYSTEM EXAMPLES
WASHING MACHINE
It is an automatic clothes washing SYSTEM
Parts: Status display panel, Switches & Dials, Motor, Power
supply & control unit, Inner water level sensor and
solenoid valve.
Rules
 Wash by spinning
 Rinse
 Drying
 Wash over by blinking
 Each step display the process stage
 In case interruption, execute only the remaining

EMBEDDED SYSTEM
Definition: An Embedded System is one that has hardware with
software embedded in it as one of its important components
SOFTWARE PROGRAM
#include <16f876a.h>
#use delay (clock=20000000)
#byte PORTB=6
main()
{
set_tris_b(0);
portb=255; //
decimal delay_ms(1000);
portb=0x55; //
hexadecimal delay_ms(1000);
portb=0b10101010; //binary
delay_ms(500);
}
HARDWAR
E

Other Definitions
 We can define an embedded system as “A microprocessor
based system that does not look like a computer”.
Or
 we can say that it is “A combination of hardware and
software, and perhaps additional mechanical or other
parts, designed to perform a dedicated function. In some
cases, embedded systems are part of a larger system or
product, as is the case of an antilock braking system in a
car ”.

Embedded systems everywhere?
Embedded systems span all aspects of modern life and there are many
examples of their use.
a) Biomedical Instrumentation – ECG Recorder, Blood cell recorder,
patient monitor system
b) Communication systems – pagers, cellular phones, cable TV
terminals, fax and transreceivers, video games and so on.
c) Peripheral controllers of a computer – Keyboard controller, DRAM
controller, DMA controller, Printer controller, LAN controller, disk
drive controller.

d) Industrial Instrumentation – Process controller, DC
motor controller, robotic systems, CNC machine
controller, close loop engine controller,
industrial moisture recorder cum controller.
e) Scientific – digital storage system, CRT
display controller, spectrum analyser.

History
• In the earliest years of
computers in 1930 – 40s,
computers were sometimes
dedicated to a single purpose
task.
• One of the first recognizably
modern embedded system was
the Apollo Guidance Computer,
developed by
Charles Stark Draper
at the MIT Instrumentation
Laboratory.

History
Since these early applications
in the 1960s, embedded systems have
come down in price and there has
been a dramatic rise in processing
power and functionality. The first
microprocessor for example, the
Intel 4004 was designed for
calculators and other small systems
but still required many external
memory and support chips.

History
By the mid-1980s, most of the
common previously external system
components had been integrated into
the same chip as the processor and
this modern form of the
microcontroller allowed an even more
widespread use, which by the end of
the decade were the norm rather than
the exception for almost all electronics
devices.

Why a microcontroller ?





A microcontroller is a single silicon chip with memory and
all Input/Output peripherals on it. Hence a
microcontroller is also popularly known as a single chip
computer. Normally, a single microcomputer has the
following features :
Arithmetic and logic unit
Memory for storing program
EEPROM for nonvolatile
data storage
RAM for storing variables and special function registers
Input/output ports

Timers and counters
Analog to digital converter





Circuits for reset, power up, serial programming,
debugging
Instruction decoder and a timing and control unit
Serial communication port

So, its no wonder to say that the microcontroller is the
most sought after device for designing an efficient
embedded system.

What is inside an embedded
system ?
Every embedded system consists of custom-built
hardware built around a Central Processing Unit (CPU).
This hardware also contains memory chips onto which
the software is loaded. The software residing on the
memory chip is also called the ‘firmware’.
The operating system runs above the hardware, and the
application software runs above the operating system.
The same architecture is applicable to any computer
including a desktop computer. However, there are
significant differences. It is not compulsory to have
an
operating system in every embedded system.

For small appliances such as remote control units, air-
conditioners, toys etc., there is no need fir an operating
system and we can write only the software specific to that
application. For applications involving complex
processing, it is advisable to have an operating system.
In such a case, you need to integrate the application
software with the operating system and then transfer the
entire software on to the memory chip. Once the
software is transferred to the memory chip, the software
will continue to run for a long time and you don’t need to
reload new software .
The next slide shows the layered architecture of an
embedded system.

Layered architecture of an Embedded System

Now let us see the details of the various building blocks of
the hardware of an embedded system.






Central Processing Unit (CPU)
Memory (Read only memory and Random access
memory)
Input Devices
Output Devices
Communication interfaces
Application specific circuitry

This slide shows the Hardware architecture of an
embedded system

Design Constraints in Embedded Systems.
1.Reliability
2.Cost effectiveness
3.Low Power Consumption.
4.Efficient use of processing power.
5.Efficient use of memory.
6.Appropriate Execution time.

Features of an embedded
system
Embedded systems do a very specific task, they cannot be
programmed to do different things.
 Embedded systems have very limited resources,
particularly the memory. Generally, they do not have
secondary storage devices such as the CDROM or the
floppy disk.
 Embedded systems have to work against some
deadlines. A specific job has to be completed
within a specific time. In some embedded systems,
called real- time systems, the deadlines are stringent.
Missing a dead line may cause a catastrophe
– loss of life or damage to property.

 Embedded systems are constrained for power, As many
embedded systems operate through a battery, the power
consumption has to be very low.
 Embedded systems need to be highly reliable. Once in
a while, pressing ALT-CTRL-DEL is OK on your desktop,
but you cannot afford to reset your embedded system.
 Some embedded systems have to operate in extreme
environmental conditions such as very high temperatures
and humidity.

 Embedded systems that address the consumer market
(for example electronic toys) are very cost-effective.
Even a reduction of Rs.10 is lot of cost saving, because
thousands or millions systems may be sold.
 Unlike desktop computers in which the hardware platform
is dominated by Intel and the operating system is
dominated by Microsoft, there is a wide variety of
processors and operating systems for the embedded
systems. So, choosing the right platform is the most
complex task .

CLASSIFICATIONS OF EMBEDDED SYSTEM
1. Small Scale Embedded
System
2. Medium Scale Embedded System
3. Sophisticated Embedded System

SMALL SCALE EMBEDDED SYSTEM
• Single 8 bit or 16bit Microcontroller.
• Little hardware and software complexity.
• They May even be battery operated.
• Usually “C” is used for developing these system.
• The need to limit power dissipation when system is
running continuously.
Programming tools:
Editor, Assembler
and Cross
Assembler

MEDIUM SCALE EMBEDDED SYSTEM
• Single or few 16 or 32 bit microcontrollers or Digital Signal
Processors (DSP) or Reduced Instructions Set Computers
(RISC).
• Both hardware and software complexity.
Programming tools:
RTOS, Source code Engineering
Tool, Integrated Development
Simulator, Debugger
and Environment (IDE).

SOPHISTICATED EMBEDDED SYSTEM
• Enormous hardware and software complexity
• Which may need scalable processor or configurable processor
and programming logic arrays.
• Constrained by the processing speed available in
their hardware units.
Programming Tools:
For these systems may not be readily available at a
reasonable cost or may not be available at all. A compiler or
retargetable compiler might have to br developed for this.

Classification of Embedded
Systems
Based on functionality and performance
requirements, embedded systems
are classified as :
 Stand-alone Embedded Systems
 Real-time Embedded Systems
 Networked Information Appliances
 Mobile Devices

Stand-alone Embedded Systems
As the name implies, stand-alone systems work in
stand-alone mode. They take inputs, process
them and produce the desired output. The
input can be electrical signals from transducers or
commands
from a human being such as the pressing of a button.
The output can be electrical signals to drive another
system, an LED display or LCD display for displaying
of information to the users. Embedded systems
used in process control, automobiles, consumer
electronic items etc. fall into this category.

Real-time Systems
Embedded systems in which some specific work has to
be done in a specific time period are called real-time
systems. For example, consider a system that
has to open a valve within 30 milliseconds when the
humidity crosses a particular threshold. If the valve is
not opened within 30 milliseconds, a catastrophe may
occur. Such systems with strict deadlines are called
hard real-time systems.

In some embedded systems, deadlines are imposed, but
not adhering to them once in a while may not lead to a
catastrophe. For example, consider a DVD player.
Suppose, you give a command to the DVD player from a
remote control, and there is a delay of a few
milliseconds in executing that command. But, this delay
won’t lead to a serious implication. Such systems are
called soft real- time systems .

Hard Real-Time Embedded System

Networked Information Appliances
Embedded systems that are provided with network
interfaces and accessed by networks such as Local Area
Network or the Internet are called networked information
appliances. Such embedded systems are connected
to a network, typically a network running TCP/IP
(Transmission Control Protocol/Internet Protocol)
protocol suite, such as the Internet or a company’s
Intranet.
These systems have emerged in recent years.
These systems run the protocol TCP/IP stack and get
connected through PPP or Ethernet to an network
and communicate with other nodes in the network.

Here are some examples of such systems
 A networked process control system consists of a
number of embedded systems connected as a local area
network. Each embedded system can send real-
time data to a central location from where the entire
process control system can be monitored. The
monitoring can be done using a web browser such as
the Internet Explorer.
 A web camera can be connected to the Internet. The
web camera can send pictures in real-time to any
computer connected to the Internet. In such a case,
the web camera has to run the HTTP server software
in addition to the TCP/IP protocol stack.

 The door lock of your home can be a small embedded
system with TCP/IP and HTTP server software running
on it. When your children stand in front of the door lock
after they return from school, the web camera in the
door-lock will send an alert to your desktop over the
Internet and then you can open the door-lock through a
click of the mouse.

This slide shows a weather monitoring system connected to the
Internet. TCP/IP protocol suite and HTTP web server software
will be running on this system. Any computer connected to the
Internet can access this system to obtain real-time weather
information.

The networked information appliances need to run the
complete TCP/IP protocol stack including the application
layer protocols. If the appliance has to provide
information over the Internet, HTTP web server software
also needs to run on the system.

Mobile Devices
Mobile devices such as mobile phones, Personal Digital
Assistants (PDAs), smart phones etc. are a special
category of embedded systems. Though the PDAs do
many general purpose tasks, they need to be designed
just like the ‘conventional’ embedded systems.

The limitations of the mobile devices – memory constraints,
small size, lack of good user interfaces such as full
fledged keyboard and display etc. are same as those
found in the embedded systems discussed above.
Hence, mobile devices are considered as embedded
systems.
However, the PDAs are now capable of supporting general
purpose application software such as word processors,
games, etc.

Languages for Programming
Embedded Systems
Assembly language was the pioneer for programming
embedded systems till recently. Nowadays there are
many more languages to program these systems. Some
of the languages are C, C++, Ada, Forth, and Java
together with its new enhancement J2ME.
The presence of tools to model the software in UML, SDL is
sufficient to indicate the maturity of embedded software
programming

The majority of software for embedded systems is still done
in C language. Recent survey indicates that
approximately 45% of the embedded software is still
being done in C language.
C++ is also increasing its presence in embedded systems.
As C++ is based on C language, thus providing
programmer the object oriented methodologies to reap
the benefits of such an approach.

C is very close to assembly programming and it allows very
easy access to underlying hardware. A huge number of
high quality compilers and debugging tools are
available for the C language.
Though C++ is theoretically more efficient than C, but some
of its compilers have bugs due to the huge size of the
language. These compilers may cause a buggy
execution.

C language can definitely claim to have more mature
compilers C++. Now in order to avail the extra benefits of
C++ and plus to avoid buggy execution, experts are
doing efforts to identify a subset of C++ that can be used
in embedded systems and this subset is called
Embedded C++ .

Communication Interfaces
For embedded systems to interact with the external world, a
number of communication interfaces are available. They
are
 Serial Communication Interfaces (SCI):
RS-232, RS-422, RS-485 etc
 Synchronous Serial Communication Interface:
I2C, JTAG, SPI, SSC and ESSI
 Universal Serial Bus (USB)

 Networks:
Ethernet, Controller Area Network, LonWorks, etc
 Timers:
PLL(s), Capture/Compare and Time Processing Units
 Discrete IO:
General Purpose Input/Output (GPIO)
 Analog to Digital/Digital to Analog (ADC/DAC)

Design of an embedded system – a
Case study
To understand the design of a simple
embedded system let us first consider
the idea of a data acquisition system.
The data acquisition system is shown in
the next slide.

For the sake of clarity I present the block diagram of a
simple embedded system.

For example let me consider a simple case
of temperature measurement
embedded system.
 First we must select a temperature
sensor like thermistor or AD590 or LM35
or LM335 or LM75 etc.
 After this the analog data is converted
into digital data and at the same time
proper signal conditioning is done.

E-m--be-dde-d -sy-s-te---m_Day_1_ES.pptx

 This digital input is fed to the
microcontroller through its ports.
 By developing a suitable program
(Embedded C or Assembly) the data is
processed and controlled.
 For this purpose keil or Ride or IAR ARM
Embedded workbench C compilers can
be used.

 Once the program is debugged, and
found error free it can be dumped into
the microcontroller flash memory using
ISP (Philips - Flash magic or any
ISP).
 Now, your microcontroller chip acts as
an embedded chip.

Which is the best suited
microcontroller for design of
embedded system?
There is always a trade off between efficiency and power
dissipation. To know this, let us review the various
types of microcontrollers and their specifications and
the vendors.

From the previous slide we can find that
the ARM processor is a strong option for
better performance. But when we
consider the power consumption, in the
case of ARM it is around 400mW and
the ATmega1031, AVR microcontroller
consumes low power around 16.5mW,
but provides low performance.

But the Texas instruments MSP430 with
wide range of operation modes
consumes only 1.2mW with reasonably
good performance. So it is always
left to the designer to choose a suitable
device according to the requirement.

Embedded C
softwares
Keil μvision evaluation version can
be downloaded from www.keil.com
Embedded C compiler Ride can be downloaded freely
from www.raisonance. com
Embedded IAR ARM Workbench can be downloaded
from
www.iar.com

The various vendors who can supply the
microcontroller kits :
1.Power systems, Chennai (www.powersoftsystems .com)
2.Vi-microsystems - Chennai(www.vimicrosystems.com)
3.ESA systems- Bangalore( www.esa india.com)
4.SPJ Embedded Technologies .Ltd. (www.spjsystems.com)
5.Advanced Electronic systems-Bangalore (www. alsindia.net)
6. Front line electronics . www. frontline-electronics. com

Website References
1. http://www.eg3.com
2. http://www.ARM.MCU.com
3. http://www.mcjournal.com
4. http://www.iar.com
5. http://www.keil.com
6. http://www.semiconductors.philips.com/microc
7. http://www.embedded.com
8. http://www.powersoftsystems.com



www.macrovision.com/newsletter
s www.planarembedded.com




www.8051.org
www.8051projects.net
www.programmersheaven.co
m microcontrollershop.com

Difference between:
– Microcomputer – a computer with a microprocessor as its
CPU. Includes memory, I/O etc.
– Microprocessor – A silicon chip which includes ALU,
registers (as a small internal memory) & a control unit.
A general purpose device (i.e. may be used for
different purposes in different applications e.g. as a
CPU in a microcomputer)
 Uses Memory, I/O functions etc external to the chip
 Configuration of the system is flexible
– Microcontroller - A silicon chip which includes
microprocessor, memory & I/O etc & other peripheral
functions all integrated on a single chip.
 More application specific, single purpose
Especially used in embedded systems
 Fixed configuration (i.e. fixed memory & other functions)

Memory
Output
Input
A Microprocessor-based system
A microprocessor based system (e.g. a
microcomputer) consists of the following components:

12/10/2024
Processor Architecture
Princeton
• Single Main Memory holding
both program and Data
• Simple memory structure
Harvard
Contains 2 separate memory
spaces- code & data
Complex memory Structure
CPU Code and Data CPU data
code

• Internally, the microprocessor is made up of
3 main units.
– The Arithmetic/Logic Unit (ALU)
– The Control Unit.
– An array of Registers as a small internal
memory for holding data while it is
being manipulated or processed.
ALU Register
Array
Control
Inside a Microprocessor

Memory of Microprocessor
• Inside (very small)
– The registers inside the microprocessor
• Outside
–Read Only Memory (ROM)
• used to store information that does not
change
–Random Access Memory (RAM)
• used to store information supplied by
the user such as programs and data.

8085 Microprocessor
• One of the most popular 8-bit general purpose
µp launched by Intel, USA in 1976
• An N-MOS chip with 40 pins & +5V supply
• Capable of addressing 216 = 64 KB of memory
• It works on 3 MHz clock.
• It has multiplexed address and data bus (AD0-AD7)
to reduce hardware (no. of pins) on the chip
• It has 74 basic instructions (formats) with 5 different
addressing modes.

Frequency
Generator is
connected to
these pins
Power
Supply: +5 V
Address latch Enable
(to activate latch to
store address
Read
Write
Input/Output/
Memory
(
Multiplexed
Address/Data
Bus
Bidirectional)
Address Bus
(Unidirectional)
To connect
slow peripherals
Interrupts
For DMA
Request
For Serial data
communication

Similar function pins are
grouped in this figure- (called
functional pin diagram)

Architecture of 8085 Microprocessor

Functions of various building blocks:
to perform all
ALU: Arithmetic & Logic Unit contains digital circuitry
arithmetic & logical operations in 8085
TIMING & CONTROL UNIT: Generates various types of control signals to
direct microprocessor what & when a task is to be performed.
INSTRUCTION DECODING & MACHINE CYCLE ENCODING: Used to
decode instruction opcode into binary form & to control various machine
cycle operations during execution of an instruction
SERIAL I/O CONTROL: Used to control serial data communication with
external devices via SID/SOD lines
INTERRUPT CONTROL: Used to handle various incoming interrupts which
occur via 5 interrupt pins TRAP, RST7.5, RST6.5, RST5.5 & INTR lines
INCREMENTER/DECREMENTER ADDRESS LATCH: It
increments/
decrements contents of Program Counter or Stack Pointer when
instructions related to them are executed.
ADDRESS & DATA BUFFERS: These are used to momentarily hold the 16
‘in-transit’ address bits while they are being placed on Address/Data bus.
These effectively act as an ‘interface’ between internal & external buses.

GENERAL PURPOSE REGISTERS (B,C,D,E,H,L): These 6 register can be used
singly to store any 8-bit data or as register pairs (valid pairs are B-C, D-E &
H-L) to perform 16-bits operations.
TEMPORAY REGISTERS (W, Z & TR): Used internally by 8085 to temporarily
store 8-bit data (or partial results) while performing various arithmetic
operations. Not available to user
ACCUMULATOR: An 8 bit register having some special features (usually
included in ALU block). It stores results of arithmetic & logical operations.
Many instructions in 8085 are Accumulator-based.
INSTRUCTION REGISTER: An 8-bit register used to hold opcode of the
instruction currently being executing
PROGRAM COUNTER: Holds 16-bits address of the next byte to fetched
during execution of an instruction & is incremented by 1 each time a byte is
fetched to point to the next memory location.
STACK POINTER: A 16-bits register which holds the address of topmost
memory location of stack. It decrements/increments by 2 each time a
PUSH/POP operation is performed
FLAG REGISTER: An 8 bit register whose individual bit are set/reset
according to status of result generated by ALU.

Tuesday, December 10, 2024
Introduction
CPU
General-
Purpose
Micro-
processor
RAM ROM I/O
Port
Timer
Serial
COM
Port
Data Bus
Address Bus
General-Purpose Microprocessor System
• CPU for Computers
• No RAM, ROM, I/O on CPU chip itself
• Example ： Intel’s x86, Motorola’s 680x0
Many chips on mother’s board
General-purpose microprocessor

RAM ROM
I/O
Port
Timer
Serial
COM
Port
Microcontroller
CPU
• A smaller computer
• On-chip RAM, ROM, I/O ports...
• Example ： Motorola’s 6811, Intel’s 8051, Zilog’s Z8 and PIC 16X
A single chip
Microcontroller :

Microprocessor
• CPU is stand-alone, RAM,
ROM, I/O, timer are separate
• designer can decide on the
amount of ROM, RAM and
I/O ports.
• expansive
• versatility
• general-purpose
Microcontroller
• CPU, RAM, ROM, I/O and
timer are all on a single chip
• fix amount of on-chip ROM,
RAM, I/O ports
• for applications in which cost,
power and space are critical
• single-purpose
Microprocessor vs. Microcontroller

1. meeting the computing needs of the task efficiently and cost
effectively
• speed, the amount of ROM and RAM, the number of I/O ports
and timers, size, packaging, power consumption
• easy to upgrade
• cost per unit
2. availability of software development tools
• assemblers, debuggers, C compilers, emulator, simulator,
technical support
3. wide availability and reliable sources of the microcontrollers.
Three criteria in Choosing a Microcontroller

12/10/2024
Classification of Microcontrollers
• μc are classified into :
– 8 bit μc e.g.: AVR 8515, Intel 8051, Motorola HC05
– 16 bit μc e.g.: Siemens 80167, Intel 80C196
– 32 bit μc e.g.:MCF5272, Power PC 8xxx
– 64 bit μc e.g.: Texas 64xxx series
• The number of bits indicate the internal data bus of a μc.
It shows how many bits of data the μc can process
simultaneously.

Block Diagram
CPU
On-chip
RAM
On-chip
ROM for
program
code
4 I/O Ports
Timer 0
Serial
Port
OSC
Interrupt
Control
External interrupts
Timer 1
Timer/Counter
Bus
Control
TxD RxD
P0 P1 P2 P3
Address/Data
Counter
Inputs

Feature 8051 8052 8031
ROM (program space in bytes) 4K 8K 0K
RAM (bytes) 128 256 128
Timers 2 3 2
I/O pins 32 32 32
Serial port 1 1 1
Interrupt sources 6 8 6
Comparison of the 8051 Family Members

8051 Architecture
• The Most Widely Used Microcontroller in the world.
• Developed by All Leading Manufacturers of Embedded
Systems.
• 8-bit Harvard Architecture
• Central Processing Unit
– 4k Bytes ROM (80C51)
– 128 Bytes RAM
– Three 16-bit Counters/Timers
• Memory Addressing Capability
– 64k ROM and 64k RAM

Pin Description of the 8051
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
RST
(RXD)P3.0
(TXD)P3.1
(T0)P3.4
(T1)P3.5
XTAL2
XTAL1
GND
(INT0)P3.2
(INT1)P3.3
(RD)P3.7
(WR)P3.6
Vcc
P0.0(AD0)
P0.1(AD1)
P0.2(AD2)
P0.3(AD3)
P0.4(AD4)
P0.5(AD5)
P0.6(AD6)
P0.7(AD7)
EA/VPP
ALE/PROG
PSEN
P2.7(A15)
P2.6(A14)
P2.5(A13)
P2.4(A12)
P2.3(A11)
P2.2(A10)
P2.1(A9)
P2.0(A8)
8051
(8031)


E-m--be-dde-d -sy-s-te---m_Day_1_ES.pptx

More Related Content

Similar to E-m--be-dde-d -sy-s-te---m_Day_1_ES.pptx (20)

Recently uploaded (20)

E-m--be-dde-d -sy-s-te---m_Day_1_ES.pptx

Editor's Notes