Embedded System and Real-time Lecture 2

Tishk International UniversityEngineering FacultyMechatronics Engineering DepartmentLecture 2: 18/10/2020

Embedded System and Real-timeLecture 2

Instructor: Dr. Rand Basil Alhashimie

Outline

• Embedded System Design Model

• Types Of Embedded System

• Processors/Devices For Embedded Systems

• Introduction To PLD’s

• Classification Of PLD’s

• Programmable Logic Devices

Model of Embedded System

• The simplest and most general form of

embedded system consists of a processors,

sensors, actuators and memory as shown in

following fig.

• Sensors: read the data from real-word

• Processor: processing unit (for the

processing of data)

• Actuators: perform appropriate actions on

the output data of the processor.

• Memory: for storage

Types of Embedded System

Embedded systems can be classified into different types based on performance & functional

requirements and performance of the microcontroller

Types of Embedded System1. Standard Embedded System

• Stand alone embedded systems do not require a host system like a computer, it works by itself.

• Examples for the stand alone embedded systems are mp3 players, digital cameras, microwave ovens

and temperature measurement systems

2. Real time Embedded System

• A real time embedded system is defined as, a system which gives a required o/p in a particular time.

• These types of embedded systems follow the time deadlines for completion of a task.

• Examples: Process control for power plants & chemical plants, medical systems for radiation therapy,

patient monitoring , telephone, radio, and satellite communications, computer games multimedia

systems


3. Networked Embedded Systems

• These types of embedded systems are related to a network to access the resources.

• The connected network can be LAN, WAN or the internet. The connection can be any wired or

wireless.

• Example for the LAN networked embedded system is a home security system

4. Mobile Embedded System

• Mobile embedded systems are used in portable embedded devices like cell phones, digital

cameras

Types of Embedded System5. Small Scale Embedded System

• These types of embedded systems are designed with a single 8 or 16-bit microcontroller, that may even

be activated by a battery.

• For developing embedded software for small scale embedded systems, the main programming tools

are an editor, assembler, cross assembler and integrated development environment (IDE).

6. Medium Scale Embedded System

• These types of embedded systems design with a single 16 or 32 bit microcontroller, RISCs or DSPs.

• These types of embedded systems have both hardware and software complexities

• For developing embedded software for medium scale embedded systems, the main programming tools

are C, C++, JAVA, Visual C++, RTOS, debugger, source code engineering tool, simulator and IDE


7. Sophisticated Embedded Systems

• These types of embedded systems have enormous hardware and software complexities, that may

need ASIPs, IPs, PLAs, scalable or configurable processors.

• They are used for cutting-edge applications that need hardware and software Co-design and

components which have to assemble in the final system

Processor List for Embedded System

PROCESSORS/DEVICES FOR EMBEDDED SYSTEMS

1. MCU:

• 4-bit MCUs: Intel 4004 (First μP) used in small applications like calculations & Toys.

• 8-bit MCUs: The most popular of this is the 8051 family.

• 16-bit MCUs: There are a few 16-bit MCUs like Intel’s 8086, 8096, 80196, some version of

PIC, etc.

• 32-bit MCUs: ARM (Advanced RISC Machine) is the most popular 32-bit MCUs use today

in image and video applications, it is used in complex applications requiring low power,

high speed, and good computing capability.


2. ASIC (APPLICATION SPECIFIC INTEGRATED CIRCUIT )

• The term 'ASIC' stands for 'application-specific integrated circuit’.

• An ASIC is basically an integrated circuit designed specifically for a special

purpose or application.

• ASIC is built only for one and only one customer.

• An example of an ASIC is an IC designed for a specific line of cellular phones of a

company.


3. FPGA (Field Programmable Gate Array)

A high capacity programmable logic device A field-programmable gate array (FPGA) is an integrated

circuit designed to be configured by the customer or designer after manufacturing—hence "field

programmable". FPGAs can be used to implement any logical function that an ASIC could perform.

SoC

A common array of n configuration for very-high-volume embedded systems is the system on a chip

(SoC) which contains a complete system consisting of multiple processors, multipliers, caches and

interfaces on a single chip. SoCs can be implemented as an application-specific integrated circuit

(ASIC) or using a field programmable gate array(FPGA).


4. DSP PROCESSORS

• A Digital Signal Processor is a specialized microprocessor with its architecture optimized

for the operational needs of digital signal processing.

• The goal of DSPs is usually to measure, filter and/or compress continuous real-world

analog signals.

• Most general-purpose microprocessors can also execute digital signal processing

algorithms successfully, but dedicated DSPs usually have better power efficiency thus

they are more suitable in portable devices such as mobile phones because of power

consumption constraints.

Introduction to PLDs (Programmable Logic Device)

Classification of PLDs

• PLA

• PAL

• PROM

• GAL

• CPLD

• FPGA

Programmable Logic Devices (PLDs)

• PLD is a general purpose chip whose hardware can be reconfigured to meet particular

specifications.

• The first PLDs were called PAL (Programmable Array Logic) or PLA

• They used only logic gates (no flip-flops), thus allowing only the implementation of combinational

circuits(a circuit whose output is dependent only on the state of its inputs).

• To overcome this problem, registered PLDs were launched soon after, which included one flip-flop

at each output of the circuit. With them, simple sequential functions (logic circuit whose output

depends not only on the present value of its input signals but on the sequence of past inputs)

could then be implemented as well.

Programmable Logic Devices (PLDs)

• Programmable Logic Devices (PLDs) were

introduced in the mid 1970s.

• PLD is a general purpose chip whose

hardware can be reconfigured to meat

particular specifications.

• Pre-fabricated building block of many

AND/OR gates (or NOR, NAND)

• "Personalized" by making or breaking

connections among the gates


• In the beginning of the 1980s, additional logic circuitry was added to each PLD output. The new

output cell, called Macrocell, contained (besides the flip-flop) logic gates and multiplexers.

Moreover, the cell itself was programmable, allowing several modes of operation. Additionally, it

provided a ‘return’ (feedback) signal from the output of the circuit to the programmable array,

which gave the PLD greater flexibility. This new PLD structure was called generic PAL (GAL).

• Several GAL devices were fabricated on the same chip, using a more sophisticated routing

scheme, more advanced silicon technology, and several additional features (like JTAG support and

interface to several logic standards). This approach became known as CPLD (Complex PLD). CPLDs

are currently very popular due to their high density, high performance, and low cost (CPLDs under

a dollar can be found).


• In the mid 1980s, FPGAs (Field Programmable Gate Arrays) were introduced.

• FPGAs differ from CPLDs in architecture, technology, built-in features, and cost. They are aimed

mainly at the implementation of large size, high-performance circuits.

1. Simple PLDsBasic Programmable Logic Operation• Depending on which of the AND/OR logic arrays is programmable, we

have three basic organizations

Programmable Logic Array (PLA)

• AND & OR Array both are

programmable in a PLA.

• PLAs come in various sizes

Typical size is 16 inputs, 32

product terms, 8 outputs.

PLA Implementation

Programmable Array Logic (PAL)

• The circuit is composed of a

programmable array of AND

gates, followed by a fixed array

of OR gates.

• Each output line permanently

connected to a specific set of

product terms

PAL Logic Implementation

PAL Logic Implementation Design Example: BCD to Gray Code Converter

Truth Table

PAL Logic Implementation Programmable PAL:

COMPARING PALS AND PLAS

• PALs have the same limitations as PLAs (small number of allowed AND terms).

• PALs have a fixed OR plane

• less flexibility than PLAs.

• PALs are simpler to manufacture, cheaper, and faster (better performance).

• PALs also often have extra circuitry connected to the output of each OR gate.

• The OR gate plus this circuitry is called a macrocell

Next Lecture

• PROGRAMMABLE ROM( PROM)

• PROM LOGIC IMPLEMENTATION

• Programmable Logic Devices

Embedded System and Real-time Lecture 2

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