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MODULE IV embedded (1).pptx

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MODULE IV embedded (1).pptx

  1. 1. MODULE IV EMBEDDED SYSTEM
  2. 2. • An embedded system is a computer system that does a specific job within a larger mechanical or electrical system, often with real-time computing constraints. • An embedded system is a system that has s/w embedded into computer h/w which makes the system dedicated for an application.
  3. 3. CHARACTERISTICS FEATURES • They cannot be programmed to do different things.It is designed to execute a single program. • Multifunctioned but single purpose • They have very limited resources like memory,I/O devices • They do not have secondary storage device such as CD ROM,floppy disk etc.The s/w is stored in ROM or in Flash memory • A specific job has to be done within a specific time(Real time) • Low power onsuption (most of them are battery operated) • Highly reliable • Less space • Low cost • Performs functions fast enough
  4. 4. • An embedded system has 3 components: • Embedded system hardware: An embedded system requires a hardware platform on which to run. The hardware will be based around a microprocessor or microcontroller. The embedded system hardware will also contain other elements including memory, input output (I/O) interfaces as well as the user interface, and the display. • Embedded system software: The embedded system software (firmware)is written to perform a particular function. It is typically written in a high level format and then compiled down to provide code that can be lodged within a non-volatile memory within the hardware. • It has an actual real-time operating system (RTOS) that defines the manner the system works.
  5. 5. EMBEDDED OS • OS acts as an interface b/w the H/W and application S/W. • It facilitates the user to format disks,create,print,copy,....display files,allocate memory locations,control the i/o operation... • In multiuser system ,it allows several users to share the CPU time,provide inter task communication,memory management......
  6. 6. SENSOR:-It measures the quantities that are physical and converts it to an electrical signal . A/D CONVERTER:- An analog-to-digital converter that converts the analog signal sent by the sensor right into a digital signal. PROCESSOR:- Processors process the digital signaland keep it to the memory. D-A CONVERTER:- A D/A converter converts the signal fed by the processor to analog information. ACTUATOR:-It is a type of motor that is operated by a source of energy, typically electric current, hydraulic fluid pressure, or pneumatic pressure, and converts that energy into motion. BASIC STRUCTURE OF AN EMBEDDED SYSTEM
  7. 7. SPECIALITIES • PERFORMANCE:-Many embedded systems have time constraints.If the deadlines are missed ,it may result catastrophe(disaster). • POWER CONSUMPTION:-Most of the embedded systems are Battery operated • COST:-should be minimum in case of office automation and consumer electronics • SIZE & WEIGHT:- important parameters in embedded system used in aircraft,missile etc. • S/W upgradation capability:- eg.PCO
  8. 8. Architecture of the RTOS
  9. 9. • The heart or nucleus of any RTOS is the kernel. Inside the kernel is the scheduler. • It is basically a set of algorithms which manage the task running order. • Multitasking definition comes from the ability of the kernel to control multiple tasks that must run within time deadlines.
  10. 10. ARCHITECTURE OF KERNEL
  11. 11. • Kernel has various functions such as file management, data transfer between the file system ,hardware management ,memory management and also the control of CPU time. The kernel also handles the Interrupts. • The Kernel is the first part of the operating system to load into memory during booting (i.e., system startup), and it remains there for the entire duration of the session because its services are required continuously. • Kernel Objects : The various kernel objects are Tasks, Task Scheduler, Interrupt Service Routines, Semaphores, Mutexes, Mailboxes, Message Queues, Pipes, Event Registers, Signals and Timers
  12. 12. OS ACTIVITIES(Kernel objects) • (i).Task: • A task is a basic unit or atomic unit of execution that can be scheduled by an RTOS to use the system resources like CPU , Memory, I/O devices etc. It starts with reading of the input data and of the internal state of the task, and terminates with the production of the results and updating the internal state. • Task States: • At any instant of time a task can be in one of the following states : • (i) Dormant • (ii).Ready • (iii).Running and • (iv).Blocked. • When a task is first created , it is in the dormant task .When it is added to RTOS for scheduling ,it is a ready task. If the input or a resource is not available ,the task gets blocked.
  13. 13. Task Scheduler: • The task scheduler establishes task time slots. Time slot width and activation depends on the available resources and priorities. • A scheduler decides which task will run next in a multitasking system. • Scheduling Algorithms: a).First in First out • (b).Round Robin algorithm • ©.Round Robin with priority • (d)Non-preemptive • (e)Pre-emptive. • The basic difference between preemptive and non-preemptive scheduling is that in preemptivescheduling the CPU is allocated to the processes for the limited time. While in Non-preemptivescheduling, the CPU is allocated to the process till it terminates or switches to waiting state. • Every RTOS provides three specific functions. (i).Scheduling (ii) Dispatching and (iii). Inter-process communication and synchronization. • The advantage of using a scheduler is the ease of implementing the sleep mode in microcontrollers which will reduce the power consumption considerably (from mA to µA). This is important in battery operated embedded systems.
  14. 14. • context switching (a process switch or a task switch) is the switching of the CPU from one process or thread to another. • A context switch is the process of storing the state of a process or of a thread, so that it can be restored and execution resumed from the same point later. This allows multiple processes to share a single CPU, and is an essential feature of a multitasking operating system.
  15. 15. • Semaphores: • A semaphore is nothing but a value or variable or data which can control the allocation of a resource among different tasks in a parallel programming environment. • Mutex is basically a locking mechanism where a process locks a resource using mutex. As long as the process has mutex, no other process can use the same resource. (Mutual exclusion ). Once process is done with resource, it releases the mutex. Here comes the concept of ownership. Mutex is locked and released by the same process/thread. It cannot happen that mutex is acquired by one process and released by other. • So, Unlike semaphores, mutexes have owners. A mutex can be unlocked only by the thread that owns it
  16. 16. Mailboxes • A Mailbox is basically a pointer size variable. A task can have a mailbox into which others can post a mail. A task or ISR sends the message to the mailbox and also receive messages through the mailbox. • A task looking for a message from an empty mailbox is blocked and placed on waiting list for a time (time out specified by the task) or until a message is received. When a message is sent to the mail box, the highest priority task waiting for the message is given the message in priority-based mailbox • Similar to our postal mailbox. When someone posts a message in our mailbox , we take out the message
  17. 17. • Message Queues ,are used to send one or more messages to a task i.e the message queues are used to establish the Inter task communication. Basically Queue is an array of mailboxes. Tasks and ISRs can send and receive messages to the Queue through services provided by the kernel. Extraction of messages from a queue follow FIFO(first in first out) or LIFO(last in first out) structure. • Applications of message queue are • • Taking the input from a keyboard • • To display output • • Reading voltages from sensors or transducers • • Data packet transmission in a network • In each of these applications, a task or an ISR deposits the message in the message queue. Other tasks can take the messages.
  18. 18. PIPES • A message pipe is an inter-process task communication tool used for inserting, deleting messages between two given interconnected task or two sets of tasks. ... Pipes are unidirectional i.e. one thread or task inserts into it and the other one reads and deletes from it..
  19. 19. Timers: • A timer is the scheduling of an event according to a predefined time value • The kernel has to keep track of different times • • A particular task may need to be executed periodically, say, every 10ms. A timer is used to keep track of this periodicity. • • A task may be waiting in a queue for a shared resource. If the resource is not available for a specified time, an appropriate action has to be taken. • The following function calls are provided to manage the timer: • • Get time • • Set time • • Time delay (in system clock ticks) • • Time delay (in seconds) • • Reset timer
  20. 20. Memory Management • It is a service provided by a kernel which allots the memory needed ,either static or dynamic for various processes. The manager optimizes the memory needs and memory utilization. • The API provides the following function calls to manage memory • • Create a memory block • • Get data from memory • • Post data in the memory • • Query a memory block • • Free the memory block
  21. 21. Handheld Operating Systems • A handheld operating system, also known as a mobile OS ,is the operating system that controls a mobile device. • The popular handheld operating systems available are (a) Palm OS (b)Symbian OS (iii)Windows CE (iv) Windows CE.NET. • Typical examples of devices running a mobile operating system are smart phones, personal digital assistants (PDAs), tablet computers …
  22. 22. REAL TIME OS • Examples for real time operating systems (RTOS) are VxWorks, µcos, Qnx, Rtlinux, window embedded etc. these are used when a specific task needs to be done in a specific time frame. • Two types • Soft RTOS:- the performance of the system is not destroyed if the timing deadlines are not met . App:- Air conditioner, TV remote or music player, Bus reservation ,automated teller machine in a bank , A Lift etc. • Hard RTOS:-the failure to meet the time dead lines may lead to a complete catastrophe or damage to the system App:- Air navigation system, Nuclear power plant , Failure of car brakes , Gas leakage system ,RADAR operation ,Air traffic control system etc.
  23. 23. Concept of AURDINO Board • Arduino Uno is a microcontroller development board based on the Atmel ATmega328 MCU. TheArduino Uno has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. • Simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started. The Arduino Uno differs from all preceding boards in that it does not use the FTDI(future technology devices international) USB-to-serial driver chip. Instead, it features the Atmega8U2 programmed as a USB-to-serial converter. The Arduino Uno MCU board can be powered via the USB connection or with an external power supply. The power source is selected automatically.
  24. 24. Concept of RASPBERRY Pi Development Board • A Raspberry Pi is a credit card-sized computer originally designed for education • The Raspberry Pi is slower than a modern laptop or desktop but is still a complete Linux computer and can provide all the expected abilities that implies, at a low-power consumption level. • There are a two Raspberry Pi models, the A and the B, A comes with 256MB of RAM and one USB port. It is cheaper and uses less power than the B. The current model B comes with a second USB port, an ethernet port for connection to a network, and 512MB of RAM • The Raspberry Pi was designed for the Linux operating system, • A Raspberry Pi is a compact computer board which offers endless opportunities. Simply plug in your TV, keyboard, mouse and power supply, and you are ready to go. There is a whole family of Raspberry Pi’s available to you, each providing various functionalities. There are also add-on boards available to enable other uses, such as camera and LCD display modules. The great thing about Raspberry Pi is that it is suitable for almost all age groups. Whether it’s introducing programming to children, or used by engineers to make complex computer-controlled systems, anyone can use one.
  25. 25. • Processor: Broadcom BCM2837 Processor Quad core A53 (ARM v8) 64-bit SoC Memory: 1GB LPDDR2 SDRAM Bluetooth: Cypress BLE chip 2.4Ghz/5.0GHz IEEE 802.11ac Ethernet: Gigabit Ethernet over USB 2.0 (300Mbps max) USB: Four USB 2.0 ports Connection: GPIO(general purpose i/o) Header 40-pin HDMI: 1 x full size Video: MIPI DSI( Mobile Industry Processor Interface Display Serial Interface connector) display port, MIPI CSI(camera serial Interface) camera port & 4 Pole stereo output and composite video port Multimedia: H.264, MPEG-4 decode (1080p30). H.264 encode (1080p30). OpenGL ES 1.1, 2.0 graphics. Storage: microSD card slot for loading operating system and data storage Power: USB connector for 5.1V / 2.5A dc

Notes de l'éditeur

  • PDA- palmtop computer,infusion pump-delivers fluids,such as nutrients & medications, artificial device that replaces a missing body part-prosthetic devices
  • PCO- public call office
  • Portable Operating System Interface -POSIX

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