History of Embedded Systems

History of Embedded Systems

• 1944: Colossus Mark 1 and Mark 2, the first programmable electronic digital computers, decrypted German messages during World War II.
• 1960s: NASA's Apollo Guidance Computer (AGC), developed at MIT by Charles Stark Draper, was the first to use integrated circuits and is considered an early embedded system.
• 1961: The Minuteman Missile 1 project spurred the Autonetics B-17 guidance computer, one of the first mass-produced embedded systems.
• 1965: The PDP-8 minicomputer became the first computer embedded in a commercial instrument.
• 1966: The Minuteman Missile 2 replaced its old guidance computer with a microelectronic guidance system, significantly reducing the cost of integrated circuits.
• 1968: Robert Noyce and Gordon Moore founded Intel, paving the way for microprocessors and microcontrollers.
• 1969: Volkswagen cars introduced the first microprocessor-based fuel injection system, a breakthrough in embedded automotive technology.
• 1971: Intel developed Intel 4004, the first 4-bit microprocessor, while Texas Instruments introduced TMS1000, one of the first successful 4-bit microcontrollers.
• 1974: Intel 8080 became the first microprocessor used in personal computers.
• 1980s: The rise of microcontrollers, optimized for power consumption and size, led to an increase in embedded applications.
• 1983: HP introduced the HP 150, an early personal computer with touchscreen technology.
• 1987: Wind River Systems introduced VxWorks, a real-time operating system (RTOS) used in NASA's Mars Pathfinder mission.
• 1992: Embedded systems became wireless; 10 million mobile phones produced using embedded technology.
• 1996: Microsoft entered the embedded market with Windows CE 1.0.
• 1999: The Linux Foundation began integrating embedded support into its OS.
• 2000: Real-time Linux was introduced, enhancing embedded system capabilities.
• 2005: Intel, IBM, and AMD released multi-core processors, boosting embedded computing power.
• 2007: Apple launched the first iPhone, integrating embedded technology in smartphones.
• 2008: The first Android phone was released; Android becoming an open-source embedded OS.

What is an Embedded System?

• An embedded system includes software and computer hardware, which makes it a software dedicated for applications or specific part of an application or product or a part of a larger system
• An embedded system is any device that includes a programmable computer but is not itself intended to be a general-purpose computer
• An embedded system is a microprocessor-based system built to control a function or range of functions and is not designed to be programmed by the end user like a PC.

Differentiating Embedded Systems from Computers

• Embedded systems are designed to perform a specific task, often with real-time constraints.
• Computers are designed for general use and can perform a wide range of tasks.
• Embedded systems typically have limited resources (processing power, memory) and are optimized for their dedicated function.
• Computers generally have well-defined user interfaces, unlike embedded systems that may have limited to no user interface.

Components of an Embedded System

• Hardware components include input/output device interfacing and driver circuits for external communication.
• Other hardware includes: a power supply, reset, oscillator circuits, processor, timers, interrupt controller, program & data memory, serial/parallel communication ports, and system-specific circuits.
• Application software includes Real Time Operating System (RTOS).

Basic Structure of an Embedded System

• Includes a sensor, A/D converter, processor & ASIC, D/A converter, actuator, and memory.

Two Main Parts of a Processor

• The control unit includes a fetch unit for fetching instructions from memory.
• The Arithmetic Logic Unit (ALU) performs arithmetic and logic operations. Results are stored in the accumulator (a short-term memory inside the ALU).

Types of Processors

• General Purpose Processor (GPP), Microprocessor, Microcontroller, Embedded Processor, Digital Signal Processor, Media Processor, Application Specific System Processor (ASSP).

Microprocessor

• Is a single VLSI chip with a CPU, along with other units like caches, floating-point processing arithmetic units, and pipelining units for faster processing.

Microcontroller

• Is a single-chip VLSI unit with limited computational abilities but enhanced I/O capabilities.
• Self-contained with a fully functional computer with built-in peripherals.
• It can stand alone and does not require any other circuitry. Found on a single integrated circuit
• Microcontrollers are cheap and small.
• Microcontrollers have simple programming.

Microprocessor vs Microcontroller

• Microprocessors are for general computing. Microcontrollers are for specialized appliances.
• Microprocessors are very fast; microcontrollers are relatively slow.
• Microprocessors have many external parts; microcontrollers have few external parts.
• Microprocessors are high cost; microcontrollers are low cost.
• Microprocessors use medium to high energy; microcontrollers use very low to low energy.

Types of Embedded Systems

• Small-Scale: Utilize a single 8 or 16-bit microcontroller, often battery-powered, with limited processing power and memory. Examples being digital watches and microwave ovens.
• Medium-Scale: Employ 16 or 32-bit microcontrollers, with increased hardware/software complexity. Examples include GPS devices and network routers.
• Sophisticated: Feature powerful 32 or 64-bit microcontrollers/processors, significant hardware and software complexity, often require RTOS. Examples are smartphones and autonomous vehicles.

Advantages of Embedded Systems

• They cover a wide range of environments and are less likely to have errors.
• Reduced cost and enhanced performance
• Useful for mass production, highly reliable, small in size, and low power operation.

Disadvantages of Embedded Systems

• Limited adaptability, high initial development costs, performance limitations, and scalability challenges.
• Security risks, limited user interface, power management challenges, and limited resources.

Coding Languages

• C and C++ are commenly used along with Assembly.

Microcontrollers

• ATMega328P and ATTiny84 are good microcontrollers.

Other tools

• In-Circuit Programmers / In-system Programmers / In-Circuit Serial Programmers and Arduino are used.

Standards and Engineering Constraints

• Include performance, efficiency, reliability, robustness, safety, and security.

Characteristics of Embedded Systems

• Single Functioned: Performs specialized operations, simple, low cost, and less complex.
• Tightly Constrained: Limited by cost, size, performance, and battery power.
• Reactive and Real Time: Must react to changes and compute results in real time.
  • Reactive they only react on input, there is no timeframe.
  • Real-Time system performs in a given time frame.
    • Soft Real-Time: Timing is less critical. Failure results in degraded performance. Ex: Personal computer
    • Hard Real-Time: Timing is critical. Failure can result in failure.
• Perform Specific Tasks: Focused on single dedicated tasks.
• User Interface: Interacts with the user through interfaces like touchscreens or LCDs.

Microcontrollers within Embedded Systems

• Factors for selecting a processor or microcontroller include: bit architecture, amount of RAM and ROM, number of I/O pins, speed, packaging, cost, on-chip features, and performance.

Main Techniques for Embedded Applications

• Embedded software is loaded in to the Microcontroller with software that controls an Embedded System.

Tools Used in Developing Embedded Software

• Editor: This is where the code is written in programming languages (C, C++), also referred to as source code.
• Compiler: Converts source code to object code, which is understandable by computers.
• Assembler: Converts assembly language code into machine language.
• Debugger: Used to debug code and tests for errors.
• Linker: Combines one or more object code files and library files together in executable programs.
• Libraries: Pre-written programs are ready to use and provide specific functionality, written in C or C++, and can be used by different programs and users.
• Simulator: Helps to see how the code will work in real time, by changing input values.

Integrated Development Environments (IDE)

• MPLAB is a proprietary freeware IDE for developing embedded applications
• Arduino Software is for Arduino microcontrollers
• MATLAB to solve computational problems
• LabVIEW: Stands for Laboratory Virtual Instrument Engineering Workbench, used for Data Acquisition, Industrial Automation and Instrument Control
• Visual Studio: IDE that supports programming languages and can build mobile apps.

Parallel Input and Output and Parallel Communication

• Parallel communication sends several data signals simultaneously over a transmission link, It comprises of several wired channels in parallel.

Characteristics of Parallel Communication

• Parallel communication transfers data fast with easy installation.
• Limited cable length can be an issue
• Parallel communication use when data needs to be transferred quickly and on time
• SCSI (connects peripherals), PCI (hardware devices), ISA (expansion cards), and EISA are examples of parallel communication.

Serial Communication

• The process of sending or receiving data one bit at a time with:
• Asynchronous Communication: Data moves in a half-paired approach, 1 byte or 1 character at a time. It sends the data in a constant current of bytes

Synchronous Transmission

• Data moves in a completely paired approach, in the form of chunks or frames
• Synchronous Transmission has no spaces.
• Provides Timing
• Chatrooms, video conferencing, telephonic conversations, and face-to-face interactions are examples of Synchronous Transmission.

Von Neumann Architecture

• CPU does one instruction at a time: fetches an instruction or read/writes data.
• This only allows the use of single sequential memory.

Harvard Architecture

• Harvard has separate storages and signal busses for instructions and data
• Harvard are used on computers and allow simultaneous access to both the instruction and data

Von-Neumann vs Harvard comparison:

• Von-Neumann uses single shared memory for code and data. Harvard uses separate memories for each.
• Von-Neumann needs to fetch code and data in separate clock cycles (slower). Harvard uses a single clock cycle.
• Von-Neumann is higher speed and simple. Harvard is slower and complex.

Instruction Set Computers

• CISC - Complex Instruction Set Computer is good with larger instructions
• RISC - Reduced Instruction Set Computer is good with simple constructs

CISC vs RISC

• CISC has a larger set of instructions. RISC has smaller.
• CISC is easy to program. RISC is difficult.
• CISC has a simpler design of compiler. RISC has a complex design of compiler.
• CISC emphasizes hardware. RISC emphasizes software.

Emulators

• A hardware kit or a software program (or both) that emulates the functions of one computer system in another.

Peripheral devices in Embedded Systems

• Serial Communication Interfaces (SCI) like RS-232, RS-422, RS-485, etc.
• Synchronous Serial Communication Interface like I2C, SPI, SSC, and ESSI
• Universal Serial Bus (USB)
• Multi Media Cards (SD Cards, Compact Flash, etc.)
• Networks like Ethernet, LonWorks, etc.
• Fieldbuses like CAN-Bus, LIN-Bus, PROFIBUS, etc.

Criteria for choosing a Microcontroller:

• Speed, packaging, power consumption, amount of RAM and ROM, count of I/O pins and Timers, and cost per unit.