CPE-412-Ch1.pdf

Embedded System Chapter 1 History and Overview Chapter 1 History and Overview Introduction This chapter introduces the reader to the planet of embedded systems. Everything that we glance around us today is electronic. The days are gone where almost everything was manual. No...

Embedded System Chapter 1 History and Overview Chapter 1 History and Overview Introduction This chapter introduces the reader to the planet of embedded systems. Everything that we glance around us today is electronic. The days are gone where almost everything was manual. Now even the food that we eat is cooked with the help of a microchip (oven) and the ease at which we wash our clothes is thanks to the washing machine. This world of electronic items is formed from embedded system. during this chapter we'll understand the fundamentals of embedded system right from its definition. Specific Objectives At the end of the lesson, the students should be able to:  Understand what is an Embedded System and then define it  Look at embedded systems from a historical point of view  Classify embedded systems  Look at certain applications & purposes of embedded systems Duration Sample: Chapter 1: History and Overview = 1 hour (45 minutes discussion; 15 minutes assessment) Lesson Proper SYSTEM - A system is an arrangement where all its component work according to the specific defined rules. It is a method of organizing, working, or performing one or more tasks according to a fixed plan. EMBEDDED SYSTEM - An embedded system can be thought of as a computer hardware system having software embedded in it. - An embedded system can be an independent system or it can be a part of a large system. - An embedded system is a microcontroller or microprocessor-based system which is designed to perform a specific task. For example, a fire alarm is an embedded system; it will sense only smoke.  History of Embedded System  In 1960, embedded system was first used for developing Apollo Guidance System by Charles Stark Draper at MIT.  In 1965, Autonetics, developed the D-17B, the computer used in the Minuteman missile guidance system.  In 1968, the first embedded system for a vehicle was released.  Texas Instruments developed the first microcontroller in 1971.  In 1987, the first embedded OS, VxWorks, was released by Wind River.  Microsoft’s Windows embedded CE in 1996.  By the late 1990s, the first embedded Linux system appeared.  The embedded market reaches $140 billion in 2013.  Analysts are projecting an Embedded market larger than $40 billion by 2030.  Three components of Embedded System  It has hardware.  It has application software.  It has Real Time Operating system (RTOS) that supervises the application software and provide mechanism to let the processor run a process as per scheduling by following a plan to control the latencies. RTOS defines the way the system works. It sets the rules during the execution of application program. A small-scale embedded system may not have RTOS.  So, we can define an embedded system as a Microcontroller based, software driven, reliable, real-time control system.  Characteristics of an Embedded System  Single-functioned − An embedded system usually performs a specialized operation and does the same repeatedly. For example: A pager always functions as a pager.  Tightly constrained − All computing systems have constraints on design metrics, but those on an embedded system can be especially tight. Design metrics is a measure of an implementation's features such as its cost, size, power, and performance. It must be of a size to fit on a single chip, must perform fast enough to process data in real time and consume minimum power to extend battery life.  Reactive and Real time − Many embedded systems must continually react to changes in the system's environment and must compute certain results in real time without any delay. Consider an example of a car cruise controller; it continually monitors and reacts to speed and brake sensors. It must compute acceleration or de-accelerations repeatedly within a limited time; a delayed computation can result in failure to control of the car.  Microprocessors based − It must be microprocessor or microcontroller based.  Memory − It must have a memory, as its software usually embeds in ROM. It does not need any secondary memories in the computer.  Connected − It must have connected peripherals to connect input and output devices.  HW-SW systems − Software is used for more features and flexibility. Hardware is used for performance and security.  Advantages  Easily Customizable  Low power consumption  Low cost  Enhanced performance  Cover a wide variety of environments  Less likely to encore errors  Useful for mass production.  Highly reliable.  Has very few interconnections.  Small in size.  Has a fast operation.   Offers improved product quality.  Optimizes the use of system resources.  Disadvantages  High development effort  Larger time to market  Embedded systems do a very specific task, so it can’t be programmed to do different things.  Offer very limited resources for memory.  It doesn’t offer any technological improvement.  It is difficult to backup of embedded files.  Basic Structure of an Embedded System The following illustration shows the basic structure of an embedded system.  Sensor − It measures the physical quantity and converts it to an electrical signal which can be read by an observer or by any electronic instrument like an A2D converter. A sensor stores the measured quantity to the memory.  A-D Converter − An analog-to-digital converter converts the analog signal sent by the sensor into a digital signal.  Processor & ASICs − Processors process the data to measure the output and store it to the memory.  D-A Converter − A digital-to-analog converter converts the digital data fed by the processor to analog data  Actuator − An actuator compares the output given by the D-A Converter to the actual (expected) output stored in it and stores the approved output.  Types of Embedded System  Stand Alone Embedded Systems Standalone embedded systems do not require a host system like a computer, it works by itself. It takes the input from the input ports either analog or digital and processes, calculates and converts the data and gives the resulting data through the connected device-Which either control, drives and displays the connected devices. Examples for the stand-alone embedded systems are mp3 players, digital cameras, video game consoles, microwave ovens and temperature measurement systems.  Real Time Embedded Systems 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. Real time embedded systems are classified into two types such as soft and hard real time systems.  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. This type of embedded system is the fastest growing area in embedded system applications. The embedded web server is a type of system wherein all embedded devices are connected to a web server and accessed and controlled by a web browser. Example for the LAN networked embedded system is a home security system wherein all sensors are connected and run on the protocol TCP/IP  Mobile Embedded Systems Mobile embedded systems are used in portable embedded devices like cell phones, mobiles, digital cameras, mp3 players and personal digital assistants, etc. The basic limitation of these devices are the other resources and limitation of memory.  Small Scale Embedded Systems 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).  Medium Scale Embedded Systems These types of embedded systems design with a single or 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.  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.  Applications of Embedded Systems Embedded systems are used in different applications like automobiles, telecommunications, smart cards, missiles, satellites, computer networking and digital consumer electronics. PROCESSOR - Processor is the heart of an embedded system. It is the basic unit that takes inputs and produces an output after processing the data. For an embedded system designer, it is necessary to have the knowledge of both microprocessors and microcontrollers.  Processors in a System A processor has two essential units.  Program Flow Control Unit (CU)  Execution Unit (EU) The CU includes a fetch unit for fetching instructions from the memory. The EU has circuits that implement the instructions pertaining to data transfer operation and data conversion from one form to another. The EU includes the Arithmetic and Logical Unit (ALU) and also the circuits that execute instructions for a program control task such as interrupt, or jump to another set of instructions. A processor runs the cycles of fetch and executes the instructions in the same sequence as they are fetched from memory.  Types of Processors Processors can be of the following categories.  General Purpose Processor (GPP) - Microprocessor - Microcontroller - Embedded Processor  - Digital Signal Processor - Media Processor  Application Specific System Processor (ASSP)  Application Specific Instruction Processors (ASIPs) The Embedded system hardware includes elements like user interface, Input/Output interfaces, display and memory, etc. Generally, an embedded system comprises power supply, processor, memory, timers, serial communication ports and system application specific circuits. References/Additional Resources/Readings Smith, J. (2021, August 27). Embedded Systems Tutorial: What is, Types, History & Examples. Guru99. https://www.guru99.com/embedded-systems-tutorial.html#5