Module-1 Embedded computing.pdf
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An embedded system is a combination of computer hardware and software designed to perform a specific function. It has three main components - hardware, application software, and an optional real-time operating system. Embedded systems are used in devices like fire alarms, cruise control systems, and digital cameras where they perform specialized tasks in real-time. Common characteristics include being single-purpose, constrained by tight design requirements like size and power consumption, and reactive to changes in their environment.
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Module-1 Embedded computing.pdf
- 1. An embedded system is a combination of computer hardware and software designed for a specific function. Embedded systems may also function within a larger system. The systems can be programmable or have a fixed functionality. 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. An embedded system has three components − 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. 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
- 2. 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 Disadvantages High development effort Larger time to market Basic Structure of an Embedded System The following illustration shows the basic structure of an embedded system −
- 3. 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. Why Use Microprocessors? ■ Microprocessors are a very efficient way to implement digital systems. ■Microprocessors make it easier to design families of products that can be built to provide various feature sets at different price points and can be extended to provide new features to keep up with rapidly changing markets. ■ Microprocessors execute programs very efficiently. Modern RISC processors can execute one instruction per clock cycle most of the time, and high performance processors can execute several instructions per cycle(MIPS).
- 4. ■Microprocessor manufacturers spend a great deal of money to make their CPUs run very fast. ■ Microprocessors generally dominate new fabrication lines because they can be manufactured in large volume and are guaranteed to command high prices. ■Microprocessors are very efficient utilizers of logic. The generality of a microprocessor and the need for a separate memory may suggest that microprocessor-based designs are inherently much larger than custom logic designs. Embedded system design process :-- An Embedded system is a controller, which controls many other electronic devices. It is a combination of embedded hardware and software. There are two types of embedded systems microprocessors and micro- controller. Micro-processor is based on von Neumann model/architecture (where program + data resides in the same memory location), it is an important part of the computer system, where external processors and peripherals are interfaced to it. It occupies more area and has more power consumption. The application of the microprocessor is personal computers. What is an Embedded System Design? A system designed with the embedding of hardware and software together for a specific function with a larger area is embedded system design. In embedded system design, a microcontroller plays a vital role. Micro- controller is based on Harvard architecture, it is an important component of an embedded system. External processor, internal memory and i/o components are interfaced with the microcontroller. It occupies less area, less power consumption. The application of microcontrollers is MP3, washing machines.
- 5. Elements of Embedded Systems Processor Microprocessor Microcontroller Digital signal processor. Steps in the Embedded System Design Process The different steps in the embedded system design flow/flow diagram include the following.
- 6. Embedded design – process – steps Abstraction In this stage the problem related to the system is abstracted. Hardware – Software Architecture Proper knowledge of hardware and software to be known before starting any design process. Extra Functional Properties Extra functions to be implemented are to be understood completely from the main design. System Related Family of Design When designing a system, one should refer to a previous system-related family of design. Modular Design Separate module designs must be made so that they can be used later on when required. Mapping Based on software mapping is done. For example, data flow and program flow are mapped into one. User Interface Design In user interface design it depends on user requirements, environment analysis and function of the system. For example, on a mobile phone if we want to reduce the power consumption of mobile phones we take care of other parameters, so that power consumption can be reduced. Refinement Every component and module must be refined appropriately so that the software team can understand. Architectural description language is used to describe the software design. Control Hierarchy Partition of structure Data structure and hierarchy
- 7. Software Procedure. Embedded Software Development Process Activities Embedded software development process activities mainly include the following. Specifications Proper specifications are to be made so that the customer who uses the product can go through the specification of the product and use it without any confusion. Designers mainly focus on specifications like hardware, design constraints, life cycle period, resultant system behavior. Architecture Hardware and Software architecture layers are specified. Components In this layer, components design is done. Components like single process processor, memories- RAM/ROM, peripheral devices, buses etc. System Integration In this layer, all the components are integrated into the system and tested whether its meeting designers, expectations. Challenges in Embedded System Design While designing any embedded system, designers face lots of challenges like as follows, Environment adaptability Power consumption Area occupied Packaging and integration Updating in hardware and software Security There are various challenges the designers face while testing the design like Embedded hardware testing, Verification stage, Validation Maintainability.
- 8. Embedded System Design Examples Automatic chocolate vending machine (ACVM) Digital camera Smart card Mobile phone Mobile, computer, etc.