EMBEDDED SYSTEMS NOTES PDF

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Engineering Class handwritten notes, exam notes, previous year questions, PDF free download. Lecture Notes (42); Assignments. Module Name, Download, Description, Download Size. Introduction, Introduction to Real Time Embedded Systems Part I , PDF, kb Introduction, Embedded Systems Components Part II, PDF, kb. Embedded System Study Materials, Important Questions List, Embedded System Syllabus, Embedded System Lecture Notes can be download in Pdf format.


Embedded Systems Notes Pdf

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Embedded Systems Design. LECTURE NOTES. SYLLABUS: Unit-I. Introduction to Embedded Systems: Definition of Embedded System, Embedded Systems Vs. Embedded Systems Notes - Download as Word Doc .doc), PDF File .pdf), Text File .txt) or read online. 67 iv. Lee & Seshia, Introduction to Embedded Systems, version least the present version is available free in the form of PDF file designed specifically for on-line reading. Notes for Instructors. At Berkeley, we use this.

Q At what stage of the design methodology would we determine what type of CPU to use 8-bit vs. We would determine what type of CPU we would use in the architecture design stage of the design methodology Q At what stage of the design methodology would we choose a programming language? We would choose a high-level programming language in the architecture design stage of the design methodology. Q Should an embedded computing system include software designed in more than one programming language?

Justify your answer. We often design performance- or power-critical code in assembly language and large, complex code in a high-level language. Subscribe to view the full document.

Understanding Embedded Systems - the basics

Q At what stage of the design methodology would we test our design for functional correctness? In a bottom-up design, we begin with individual components that could comprise a system and work our way up to eventual complete a full system. In contrast, in a top-down design, we begin with an abstract notion of a device and work our way down to the components that comprise the system.

Of course, both methods are similar from the standpoint that the net result is a finished product. However, they both obviously achieve this result in completely different ways. When erased, the bits in that sector are set to 1. As it is electrically erasable, contents of the flash memory can be updated in the embedded system. Flash memory is nowadays extensively used in embedded systems for storing the firmware.

Characteristics of an Embedded System

Clock Circuitry The processor has to be given the clock input to one of the pins. To generate the clock signal, a crystal and oscillator are required. For some processors, the oscillator circuitry is inbuilt, only external crystal has to be added to generate the clock signal.

Real time clock RTC keeps track of the date and time. All processor events are related to the clock. The higher the clock frequency, the higher the speed of the processor. However, different processors cannot be compared based on clock speed alone.

One processor may take one clock cycle for executing an instruction, whereas another processor may take 16 clock cycles to execute the same instruction. Due to some software or hardware error, a need may arise to reset the processor. The watchdog timer does the resetting. A timer is set to a large value and it is decremented slowly. If the timer value reaches zero, the 14 processor is reset through a reset signal.

If everything is going on fine, intermittently, the timer value is again set to the large value. If a reset button is provided in an embedded system, on pressing the button, a reset signal is sent to the processor. Alternatively, the processor sends a periodic signal to the reset circuit indicating that it is healthy. If the reset circuitry does not receive this signal, then the processor is reset. The processor performs this identification using a signal called chip select CS.

The chip select signal is available to all the peripherals connected to the bus. This is achieved through sensors and transducers. Temperature sensors convert the temperature into an equivalent electrical voltage.

The output of the sensor is a signal whose voltage level is proportional to the temperature. Measurement of temperatures in air conditioners, boilers, coffins etc is done through this sensor. Light sensors convert the light intensity into an equivalent electrical voltage.

The output of the sensor, the voltage level, is proportional to the light incident on the sensor. The light is sensed through a photodiode, and an in-built amplifier amplifies the voltage level. Accelerometer converts the acceleration into voltage. The voltage is proportional to the acceleration of a vehicle. Pressure sensors convert the pressure level to voltage level.

Pressure sensors are used in blood pressure equipment, and to measure altitude of aircraft, ocean depth etc. MPXA A is an example. Microphone and speakers : Microphone converts the acoustic energy into a voltage signal. When you speak into a microphone, the output of the microphone is an electrical signal Some important sensors and 15 with continuously varying amplitude.

The speakers convert the electrical signal back into acoustic waves. Video camera and monitor : The real life image or scenery is converted into electrical signal using a video camera.

The video camera output is a continuously varying electrical signal. The electrical signal is converted back to the image on a monitor. Their amplitude continuously varies with time. However, the computing devices are digital. They can process only digital data. Hence, we need to convert the analog signals into digital data. The analog signals produced by sensors and transducers have one important characteristic i.

The bandwidth of a signal is the highest significant frequency component present in the signal.

For instance, voice signals have a bandwidth of 4 KHz, i. The analog signal can be converted into digital format in two stages: sampling and quantization.

In sampling, the amplitude levels of the signal are measured at regular intervals. In quantization, the sampled value is converted into a number.

Nyquist theorem provides the number of samples required to correctly represent an analog signal. If the bandwidth of a signal is B Hz , the number of samples required per second called the sampling rate should be at least 2B.

So, for voice signals with a bandwidth of 4 KHz, the minimum sampling rate is samples per second. These samples are quantized by dividing the complete range of amplitudes into say levels. These levels are quantization levels. To represent the levels, 8 bits are required. Hence, to represent each sample value, 8 bits are required. To represent levels, 12 bits are required. This process of sampling and quantization is done through analog to digital converter ADC chips.

The reverse process of converting the digital signal to analog signal is done through Digital to Analog converter DAC. A representative function keypad is shown in Fig 3. This keypad has been designed to do the functions of controlling a tape recorder. It has various buttons for play, record, pause, fast forward, go to first file, go to last file etc.

Fig 3. Red, green and yellow LEDs are used for status display as well as for indications of visual alarms for such events as power supply failure. Blue and white LEDs are also available, but they are very expensive.

LCD is used to display the status information or to display prompts to the user. The display can be as small as 1 line with 8 characters. Other displays used in embedded systems can be of 6. The diagonal distance is indicated as display size.

Resolution can be x or x etc. The display driver circuitry is connected to the processor. Communication Interfaces For embedded systems to interact with the external world, a number of communication interfaces are provided. Earlier, many processor manufacturers provide proprietary interfaces to do the debugging. JTAG port provides access to the internals of the processor. The standard IEEE JTAG port can also be used to download the software onto the embedded system.

Power Supply Unit An embedded system operates either through a V mains supply or through a battery. The batteries give different voltages, but the output is not stable and the power supply unit has to derive the necessary voltages from this DC voltage.

Voltage regulators are used for this purpose. The input to a voltage regulator is a range of DC voltages and the output is stable fixed voltage.

The operating system is optional, if it is not present, you need to write your own software routines to access the hardware. As embedded systems are constrained for memory, we cannot use an operating system such as Windows or Unix on them. But still, we need the services provided by an operating system.

Operating System Every computing device, whether it is a mainframe, desktop computer or an embedded system, needs a piece of software using which the user interacts with the hardware. This software is the operating system OS. When we invoke an application, say, word processing software, this application is loaded into the RAM. We can use the computer for doing different things simultaneously such as word processing, downloading the email etc.

Each job is done by invoking an application software package. To write an application software package, we divide the job into different smaller jobs, write the code for each smaller job and then combine the entire code.

In case of a desktop system, each job is called a process and in an embedded system, each job is called a task. Managing these multiple tasks is done by the OS. However, as compared to desktops, embedded systems have special requirements as described below: Reliability The OS in an embedded system has to be very reliable. If the system has to have an availability of All operating systems used in embedded systems support this feature. But then, the task management has to be done efficiently to meet the real-time performance requirements.

Desktop operating systems do not support realtime requirements whereas embedded systems must meet definite deadlines for some tasks. Small footprint As the memory devices have limited capacity in embedded systems, they have little memory for the OS. Many frills provided by operating systems such as windows are not provided in embedded operating systems. The memory occupied by the operating system is known as the footprint. The footprint should be very small for an embedded OS. Support for diskless systems Unlike the desktop computers, embedded systems may not have secondary storage such as hard disk or CD-ROM.

The embedded OS along with application software will reside on a memory chip. File system management is not mandatory in embedded systems. However, if the application demands a file system, you can create a small file system on the flash memory.

Portability A variety of processors are available for developing embedded systems unlike desktop computers whose processors are predominantly the Intel family processors. So, an important requirement of embedded operating systems is portability. Scalability The embedded operating systems may be used on an 8-bit microcontroller or a powerful 16bit microprocessor.

So, scalability is very important for embedded operating systems. API is a set of function calls. An application developed for one OS may not be portable to another OS. Operating systems used in embedded systems must comply with this standard. Architecture of Embedded Operating Systems 20 The architecture of an embedded operating system is shown in fig.

The software in an embedded system can be divided into the operating system and the applications software.

The in-between layer, the Application Programming Interface API , is used by the developers to write the application software. API provides the function calls to access the operating system services. Kernel manages the tasks to achieve the desired performance of the embedded system. To manage the tasks, the important requirements are schedule the tasks and to provide inter task communication facilities.

To achieve these two requirements, kernel objects are defined such as tasks, mutexes, ISRs, events message boxes, mail boxes, pipes and timers.

Device drivers provide the necessary interface between the application and the hardware. Communication protocol software: If the embedded system has communication interfaces such as Ethernet, USB etc.

Then the embedded system can be network-enabled. File system: Most of the embedded systems do not have a secondary storage. In such cases, the ROM is used to store the program. In case a file system is required, a small file system can be developed on Flash memory.

Some embedded systems may use a secondary storage just for booting. Most of the embedded software was written only in assembly language and hence writing, debugging and maintaining the code were very difficult and time consuming. With the availability of powerful processors and advanced development tools, embedded development is not difficult. About varieties of processors are available from around 50 semiconductor vendors.

Powerful 8-bit, bit, bit, bit microcontrollers and microprocessors are available to cater to the different market segments. The clock speed and the memory addressing capability of these processors are also increasing. Very powerful Digital Signal Processors are also available for real time analysis of audio and video signals. As a result, the embedded systems can be made functionally rich by incorporating additional features such as networking protocols and even graphical user interfaces.

The cost of memory chips used to discourage developers from porting an operating system onto the target hardware. As the memory chips are becoming cheaper, porting an operating system is no longer an issue.

Now wristwatches with embedded Linux operating system are available. The software 23 can be developed in a high level language such as C. So, time to market the system gets reduced. If real time performance is required, a real-time operating system can be used such as VxWorks, RTLinux etc.

Network enabling of an embedded system has many advantages : it can be accessed over a network for remote control or monitoring. Besides, upgrading the embedded software is very easy as the new version can be uploaded through the network interface. The main attraction of Java is its platform independence. In fact, the development of Java programming language was initiated mainly to address the embedded system market.

Many exciting applications are possible by having a Java Virtual Machine in an embedded system. It enables the system to download Java applets from a server and execute them. Microsoft embedded visual tools can be used for development of embedded software applications.

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Development tools such as MATLAB and Simulink can be used to model an embedded system as well as to generate code, substantially reducing the development time. The entire application can be developed and tested on desktop computers, and then deployed in the field. After developing the prototype of an embedded system, for mass production, an FPGA can be developed which will have all the functionality of the processor, peripherals as well as the application specific circuitry.

These are the tiny, quick, and smart microprocessors that live inside printers, answering machines, elevators, cars, cash machines, refrigerators, thermostats, wristwatches, and even toasters. Embedded systems are on the cutting edge of consumer electronics, poised to revolutionize various technologies by making them "smarter.

Todays high tech car has about 20 embedded systems for transmission control, engine spark control, air-conditioning, navigation etc. Even wristwatches are now becoming embedded systems. The palmtops are powerful embedded systems using which we can carry out many general purpose tasks such as playing games and word processing. Digital diary : Casio digital diaries are electronic organizers capable of storing hundreds or thousands of memo, address, and schedule records.

They were produced by Casio in the early and mid s, but have since been entirely superseded by Mobile Phones and PDA's. Casio digital diaries hosted a common set of features while some have had extra features specific to the model.

Features: i Telephone directory Enter the first letter of a name to recall the name in an instant Initial Search. Data is sorted automatically in alphabetical order. Once a password is registered, data is locked away until the password is used to access the secret area. Modem : A modem modulator-demodulator is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data.

Modems can be used over any means of transmitting analog signals, from light emitting diodes to radio. The most familiar example is a voice band modem that turns the digital data of a personal computer into modulated electrical signals in the voice frequency range of a telephone channel.

These signals can be transmitted over telephone lines and demodulated by another modem at the receiver side to recover the digital data. Modems can alternatively be classified by their symbol rate, measured in baud.

The baud unit denotes symbols per second, or the number of times per second the modem sends a new signal.

The embedded systems for industrial use are designed to carry out specific tasks such as monitoring the temperature, pressure, humidity, voltage, current etc. In hazardous industrial environment, where human presence has to be avoided, robots are used, which are programmed to do specific jobs. The robots are now becoming very powerful and carry out many interesting and complicated tasks such as hardware assembly. Thirty years earlier, the Volkswagen used a microprocessor to control its fuel injection, making it the first embedded system in the auto industry.

Today, a car's electronics cost more than the steel used to build it, and high-end cars can have more than CPUs. Industrial Robot: An industrial robot is as an automatically controlled, reprogrammable, multipurpose manipulator programmable in three or more axes.

The field of robotics may be more practically defined as the study, design and use of robot systems for manufacturing. Typical applications of robots include welding, painting, assembly, pick and place such as packaging, palletizing and SMT , product inspection, and testing; all accomplished with high endurance, speed, and precision. These equipments include diagnostic aids such as ECG, EEG, blood pressure measuring devices, Xray scanners; equipment used in blood analysis, radiation, colonoscopy, endoscopy etc.

Developments in medical electronics have paved way for more accurate diagnosis of diseases. Electrocardiography ECG : Electrocardiography ECG or EKG from the Dutch Electrokardiogram is a transthoracic across the thorax or chest interpretation of the electrical activity of the heart over a period of Time, as detected by electrodes attached to the outer surface of the skin and recorded by a device external to the body.

An electrocardiogram ECG is a test that records the electrical activity of the heart. ECG is used to measure the rate and regularity of heartbeats as well as the size and position of the chambers, the presence of any damage to the heart, and the effects of drugs or devices used to regulate the heart such as a pacemaker.

EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain. In clinical contexts, EEG refers to the recording of the brain's spontaneous electrical activity over a short period of time, usually minutes, as recorded from multiple electrodes placed on the scalp.

Diagnostic applications generally focus on the spectral content of EEG, that is, the type of neural oscillations that can be observed in EEG signals. In neurology, the main diagnostic application of EEG is in the case of epilepsy, as epileptic activity can create clear abnormalities on a standard EEG study. A secondary clinical use of EEG is in the diagnosis of coma, encephalopathies, and brain death. Despite limited spatial resolution, EEG continues to be a valuable tool for research and diagnosis, especially when millisecond-range temporal resolution not possible with CT or MRI is required.

For example, a router interconnects two networks. The two networks may be running different protocol stacks. The routers function is to obtain the data packets from incoming ports, analyze the packets and send them towards the destination after doing necessary protocol conversion. Most networking equipments, other than the end-systems desktop computers we use to access the networks, are embedded systems. It uses asynchronous time-division multiplexing, and it encodes data into small, fixed-sized cells.

Embedded System Lecture Notes and Presentations

This differs from approaches such as the Internet Protocol or Ethernet that use variable sized packets or frames. ATM has functional similarity with both circuit switched networking and small packet switched networking. It was designed for a network that must handle both traditional high-throughput data traffic e.

ATM uses a connection-oriented model in which a virtual circuit must be established between two endpoints before the actual data exchange begins. The subscriber terminals such as key telephones, ISDN phones, terminal adapters, web cameras are embedded systems.

The network equipment includes multiplexers, multiple access systems, Packet Assemblers Dis-assemblers PADs , satellite modems etc. IP phone, IP gateway, IP gatekeeper etc are the latest embedded systems that provide very low-cost voice communication over the Internet. Web camera: A webcam is a video camera that feeds its images in real time to a computer or computer network, often via USB, ethernet, or Wi-Fi. Their most popular use is the establishment of video links, permitting computers to act as videophones or videoconference stations.

This common use as a video camera for the World Wide Web gave the webcam its name. Other popular uses include security surveillance and computer vision and there are also uses on sites like video broadcasting services and for recording social videos.

Webcams are known for their low manufacturing cost and flexibility, making them the lowest cost form of videotelephony. They have also become a source of security and privacy issues, as some built-in webcams can be remotely activated via spyware.

It collects data from a group of terminals and places the data into X.If the deadlines are missed, it may result in a catastrophe. Embedded systems used in process control, automobiles, consumer electronic items etc. Some embedded systems have to operate in extreme environmental conditions such as very high temperatures and humidity. Biometric systems using fingerprints and face recognition are now being extensively used for user authentication in banking applications as well as for access control in high security buildings.

Characteristics, quality attributes application specific, domain-specific, embedded systems. Architecture of Embedded Operating Systems 20 The architecture of an embedded operating system is shown in fig.

If there is a delay in tracking the aircraft and if the missile misses the deadline, the enemy aircraft may drop a bomb and cause loss of many lives. First bug story; effective test plans; testing won't find all bugs; F Raptor date line bug; bug farms; risks of bad software.

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