Introduction to embedded System.pptx
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This document provides an introduction and overview of embedded systems and embedded system design. It discusses the following key points in 3 sentences: 1. It defines embedded systems and lists their essential components as well as characteristics including low cost, low power usage, and small size. 2. It discusses the requirements of embedded microcontroller cores including memory, ports, timers, interrupts, and serial data transfer standards to interface with real-world peripherals. 3. It also covers embedded programming, real-time operating systems, example applications, and textbooks on embedded systems design.
Introduction to embedded System.pptx
- 1. Introduction to Embedded Systems Lecture 1 Date 8/9/2010
- 2. Subject Code: 710409 Subject Name: Embedded Systems Course Hand Out Topic No. Name of the Topic 1 Introduction to Embedded system design (ESD) and Products; Requirements of Embedded controller core and Memories, DRAM Controller 2 Introduction to ARM7 controllers and architecture (Timers, interrupts, UART, SPI, details) 3 Embedded Programming (cross compiler, Hardware Emulation, C and assembly interfacing) 4 Introduction to serial data transfer standards, SCI, SPI, UART, USB technologies, JTAG interface 5 Signal conditioning, interfacing with real world peripherals, ADC and DAC interfacing 6 Real Time Operating System Concepts (Scheduler Algorithms, Multitasking, Threading) 7 Applications and studies: Phones, PDAs, ATM, Digital Cameras, J2ME of Embedded systems 8 Seminars on relevant topics
- 3. List of Books Text Books 1 Title Author Publisher Embedded Microcomputer Systems Real Time Interfacing Jonathan W. Valvano Thomson Books 2 Title Author Publisher Embedded Systems Design, 2nd edition Steve Heath Newnws ( Elsevier ) Reference Books 1 Title Author Publisher The 8051 Microcontroller K J Ayala Penram Intl. 2 Title Author Publisher Embedded Systems: Architecture, Programming and Design Raj Kumar Mc Graw Hill 3 Title Author Publisher Embedded/Real Time Systems: Concept, Design and Programming Dr. K V K K Prasad Dreamtech Press 4 Title: Author: Publisher: Embedded Systems Architecture : A Comprehensive Guide for Engineers and Programmers Tammy Noergaard Newnws (Elsevier)
- 4. What is an Embedded System An Embedded System is a microprocessor based system that is embedded as a subsystem, in a larger system (which may or may not be a computer system). O I
- 5. • Monitoring / controlling the physical world. • A user can make choices concerning functionality but cannot change the functionality of the system by adding / replacing software • It is having capability to provide upgradation about the functionality
- 6. Application areas • Automotive electronics • Aircraft electronics • Trains • Telecommunication
- 7. Application areas • Authentication • Military applications • Medical systems
- 8. Application areas • Consumer electronics • Smart buildings • Fabrication equipment
- 9. Essential Components • Microprocessor / DSP • Sensors • Converters (A-D and D-A) • Actuators • Memory (On-chip and Off chip) • Communication path with the interacting environment
- 10. Embedded System Structure (Generic) Memory Processor & ASICs A- D Sensor D- A Actuator
- 11. Characteristics of Microcontroller to design an embedded system • Low cost • Low speed, on the order of 10 KHz – 20 MHz • Low Power, extremely low power in sleep mode • Small architecture, usually an 8-bit architecture • Small memory size, but usually enough for the type of application it is intended for. Onboard Flash. • Limited I/O, but again, enough for the type of application intended for
- 12. Example – Weighing scale
- 13. Harvard Architecture 1) Harvard Architecture refers to a memory structure where the processor is connected to two different memory banks via two sets of buses 2) This is to provide the processor with two distinct data paths, one for instruction and one for data 3) Through this scheme, the CPU can read both an instruction and data from the respective memory banks at the same time 4) A Harvard architecture computer can thus be faster for a given circuit complexity because instruction fetches and data access do not contend for a single memory pathway. 5) The cost of such a system is complexity in hardware Commonly used in DSPs.
- 14. Von – Neumann Architecture 1) A Von-Neumann Machine, in contrast to the Harvard Architecture provides one data path (bus) for both instruction and data 2) As a result, the CPU can either be fetching an instruction from memory, or read/writing data to it 3) Other than less complexity of hardware, it allows for using a single, sequential memory. 4) Today’s processing speeds vastly outpace memory access times, and we employ a very fast but small amount of memory (cache) local to the processor 5) Modern processors employ a Harvard Architecture to read from two instruction and data caches, when at the same time using a Von-Neumann Architecture to access external memory
- 15. Big vs. Little Endian format of storing data in memory Although numbers are always displayed in the same way, they are not stored in the same way in memory Big-Endian machines store the most significant byte of data in the lowest memory address Little-Endian machines on the other hand, store the least significant byte of data in the lowest memory address A Big-Endian machine stores 0x12345678 as: A Little-Endian machine stores 0x12345678 as: ADD+0: 0x12 ADD+1: 0x34 ADD+2: 0x56 ADD+3: 0x78 ADD+0: 0x78 ADD+1: 0x56 ADD+2: 0x34 ADD+3: 0x12
- 16. Contd. The Intel family of Microprocessors and processors from Digital Equipment Corporation use Little-Endian Mode Whereas Architectures from Sun, IBM, and Motorola are Big-Endian Architectures such as PowerPC, MIPS, and Intel’s IA- 64 are Bi-Endian, supporting either mode
- 17. Characteristics of Embedded Systems Embedded Systems, unlike a PC, never “exit” an application They idle through an Infinite Loop waiting for an event to happen in the form of an interrupt, or a pre- scheduled task In order to save power, some processors enter special sleep or wait modes instead of idling through an Infinite Loop, but they will come out of this mode upon either a timer or an External Interrupt
- 18. Essential Considerations • Response Time -- Real Time Systems • Area • Cost • Portability • Low Power (Battery Life)
- 19. ES, MS and RTS • All embedded systems are microprocessor based systems, but all microprocessor based systems may not be amenable to embedding (Area, Power, Cost, Payload parameters). • Most of the embedded systems have real time constraints, but there may be ES which are not hard RTS (for example off line Palm tops) • There may be RTS which are not embedded (e.g. Separate Process Control Computers in a network) • Embedded Systems are not general purpose systems; they are designed for dedicated applications with specific interfaces with the sphere of control
- 20. Hard Real vs. Soft Real • The correctness of the system depends not only on the results of computations, but also on the time at which the results are produced. • Hard real time system are time bounded while soft real time systems are not.
- 21. A real-time system in which a missed deadline causes the work performed to have no value or to result in a catastrophic event.
- 22. A real-time system in which a missed deadline does not compromise the integrity of the system or result in a catastrophic event.
- 23. Examples • Hard real time systems 1. Traffic signal controllers 2. Anti-Lock brake systems 3. Manufacturing plant controllers 4. Medical devices • Soft real time systems 1. Set Top Boxes 2. Consumer Electronics
- 24. General Characteristics of Embedded Systems • Perform a single task – Usually not general purpose • Increasingly high performance and real time constrained • Power, cost and reliability are important considerations • HW-SW systems – Software is used for more features and flexibility – Hardware (processors, ASICs, memory etc. are used for performance and security
- 25. General Characteristics of Embedded Systems (contd.) ASIC s Processor Cores ASIPs and ASICs form a significant component – Adv: customization lower power, cost and enhanced performance – Disadv: higher development effort (debuggers, compilers etc.) and larger time to market Mem Analog IO Digital
- 26. Lecture 2 Requirement of Embedded Microcontroller Core
- 27. What is a Microcontroller • Flash + RAM on the chip • Ports with sufficient driving capacity • Timers • Interrupts • Serial data transfer engines like SPI, UART, I2C • For DSP applications DMA controller and MAC unit
- 28. Memory Requirements • Flash memory holds the program code • RAM will hold the dynamic data associated with the program • Boot loader resides in flash that helps in communicating with program in PC to load the application program in flash • Microcontrollers generally do not use ROM but rather EEPROM is provided as flash on the chip • External Memory interfacing is avoided due to varities of option available from each manufacturer in the form of required flash memory on the core. For example 8051 (4KB), 8052(8KB), 8055(20KB), P89c51RD2(64KB).
- 29. Port Requirements • In case of 8085 based system we need to have 8255 to assign a port to input or output device. • In embedded system we want the port structure on the core of microcontroller. Hence Micon. will have port structure defined on it. • To save the pins the ports have dual pin functions.
- 30. • Ports are bidirectional with latch for output as well as if possible having sufficient driving capacity (but not necessary) • Port pins are bit addressable
- 31. Timer Requirements • Timer is present on the core to generate timing signals for various peripherals like ADC, RTC, SPI, UART etc. • The frequency of timer is programmable. • Timer must have interrupt associated with its operation. • Watch dog timer in debugging environment. • Timer as counter to count external events.
- 32. Multiplexed Display with timer
- 33. Interrupts • Polled I/O is slower hence Interrupt driven data transfer is better approach. • Hardware / Software Interrupt. • Exceptions • Important activities on the architectural level are associated with Interrupt to reduce the tasks handled by Main program. • Multitasking is implemented with the help of Interrupts in Real Time Operating System Environment.
- 34. Interrupt can be associated with following kind of activities: Timer overflow ADC conversion completed Data is received on UART port Some port pin is activated with active signal. Etc…….
- 35. Interrupts with Timer • When a timing event is generated Interrupt occurs. • Timing events (a) Roll over of the timer (b) Timer count = Match register
- 36. Idle / Power Down Modes • Power can be shut down to selected segments of the architecture. • Retention of the RAM contents is followed in the power down modes. • In “Embedded Operating Systems” environment, power down mode saves power in between successive systems ‘ticks’. • Hardware reset or interrupt can be used to quit the power down mode.
- 37. Philosophy of Microcontrollers • Special Function Registers enable / disable the resources as per requirement. • The functioning associated with the resources (ADC, Timer etc.) are controlled by the respective SFRs. • This controls the power consumption. • This also makes it possible for dual / triple pin functions.
Editor's Notes
- #5: Highlight the interaction with the environment Input output communications require proper transduction and actuation So A/D conversion requirements can also be mentioned here A very important aspect that should be mentioned is that the design of the hardware and software of the ES derives its specifications from the environment with which it will interact