Introduction to Embedded Systems and history.pptx

Introduction to Embedded Systems

1. Introduction to Embedded Systems

2. Introduction From hardware specific designs to general platforms

3. Systems Around Us Devices interact with their environment Receiving Inputs (Sensors that capture changes/events in the environment) Processing (inputs, current and/or past states) Sending Outputs (responding to environment through actuators) Processing decides what response to send for given input Can be electronic, mechanical or other types Should be able to understand and interpret inputs Should be able to control behavior of outputs Input Output Process

4. Electronic Systems Use sensors (transducers) to convert a physical phenomenon into an electric (voltage, current) signal and capture as inputs Switches Keyboards Transducers ( encoders , pressure sensors , gyroscopes, voltage/ current sensors etc.) Process inputs electrically Work according to a predefined algorithm or a process Generate voltages and currents that are required by the actuators to create necessary output in the required form

5. Analog Systems Analog signals are prone to noise and variations (line resistances etc.) Processing is built into the design – non-flexible design May use non-solid state devices Difficult to design, manufacture and expensive to maintain Analog Sensors Analog Actuators Analog Processing Real World Real World

6. Problems with Analog Systems Analog signals are prone to noise and interference Simple loose connection or a long exposed cable may change the signal travelling through that A sensor may output a signal with 0.7V, but by the time it reach the processing circuit, voltage may have dropped down to 0.65V or may be corrupted with a random noise with 0.9V peak to peak. Low error margins – need precision components and designs Discrete signals can help in solving these problems Higher error margins Deterministic values – can recover from corrupted signals

7. Digital Systems Natural world is Analog – often need to convert to digital and back Digital signals are more immune to noise and other interferences Processing based on Boolean algebra (digital logic) Design more flexible than analog ones – more unified design approach Design is rigid but more flexible than analog designs Easier to design, manufacture and less expensive to maintain Real World AtoD conv. DtoA conv. Digital Processing Real World Analog Sensors Analog Actuator

8. Designing Systems (Digital or Analog) Designing and building an electronic system is not easy Need to understand the problem domain Decide what inputs to capture and what outputs to produce Decide how to derive output from inputs Design the circuit addressing various issues such as noise, signal interference, power consumption etc. Design the printed circuit board and other accessories Manufacture and package Market Continue support and maintenance over a period of time Each design is unique – a change in a single component may require entire design to be re-done Difficult and expensive

9. Problem Difficulty in climbing steps

10. More Flexible Designs Most systems have common input/output features but differ on how they are processed Can we separate input/output from processing? Can we make processing to be flexible and independent from the hardware design? Can we change processing without changing hardware design? Can we have the same processing but using different hardware setup? Solution came from a different industry A textile looms producing different patterns using the same machine Provided initial steps towards automation See next slide for a video

11. Joseph Jacquard’s Power Loom https://www.youtube.com/watch?v=f1Zzj9ZBYmQ

12. Extending Joseph Jacquard’s idea - Microprocessor Based Systems

13. What is an Embedded System..? Many Definitions A microprocessor-based system Built to control function(s) Not designed to be programmed by the end user User can make choices/select options but cant change software What about a PC?

14. Microprocessor Based Systems - Benefits Use of common components – savings in cost Majority of hardware components and architecture will remain common across multiple devices, versions or configurations Support standardization and component re-usability Can be built using readily available, standard components Trusted platforms, more tools and support available Software is easier to maintain compared to hardware designs Software allows more complex logic/algorithms at lesser cost Better control and smooth operations More flexible More functional

15. Example – Railway Signaling Systems

16. Signal Point Control Module Each control module handles one signal point Backplane bus provide a common communication path to all signal points and their respective control modules Each control module is a “hot-pluggable” card that has a standard interface Receive inputs from track sensors. Generate outputs that control signal lights and track changing points. Mapping from inputs to output is a unique for each signal point Hardware/Software Designs Hardware based approach Control algorithm is built into the hardware logic. Each board becomes a custom built circuit for that signal point. Software based approach Algorithm is in software – different software modules running on the same hardware platform

17. Hardware/Software Approach – Key Benefits Hardware becomes standard across multiple modules Reduction of cost through large scale production Use readily available components More reliable components, designs and modules Less dependency on specific parts/architectures Facilitates maintainability Place hardware in a “Black-box” and build all operational logic in to “software algorithms” “Processing logic” is independent of hardware design Maintenance and upgrades through software Support complex logic on the same platform

18. Hardware/Software Approach – Economic Benefits Economics of standardization Sales cost and profit margin of a product is not limited to material & manufacturing costs Sales price usually consist of Material cost Manufacturing (plant & labor) Marketing, sales costs and profit margin NRE cost per unit Inventory and souring cost Spares, warranty and maintenance Use of standard components and standardization of inventory can help in reducing many of the above, especially those in red color.

19. Hardware/Software Approach – Economic Benefits Breakdown of world’s semiconductor production

20. Hardware/Software Approach – Other Benefits Shorter design/development time Reduction in time-to-prototype/time-to-market windows – bring competitive advantage over others Readily available resources Development tools, testing tools, developers and other resources Protection of intellectual prop erty IP is included in the software – easier to protect against reverse engineering Flexible and re-usable designs Easy maintenance and upgrades Mostly through software – even at end-users location or through remote management

21. What led the (increasingly) widespread use of HW/SW approach? Replacement of discrete logic-based circuits Providing functional upgrades Providing easy maintenance upgrades Improving mechanical performance Protection of intellectual property Replacement for analog circuits Since integrated circuit design was (and still is) an expensive and time consuming process, the ability to reuse the hardware design by changing the software was a key breakthrough.

22. What led the widespread use of Hw / Sw approach? Replacement of discrete logic-based circuits Up to 1970, most control systems used integrated circuits First microprocessor was a programmable replacement for the calculator chips Before that calculator functionality was based on logic chips Changes or improvements in any system required to develop new chips Creating new functions by analyzing the gate level logic and modifying it A very time consuming process The answer was to build a chip that had some form of programmable capacity in it Why not build a chip that took data in process and send the results out? New products could be created by changing the program code

23. What led the widespread use of Hw / Sw approach? Providing functional upgrades Ability to add/remove functionality from embedded systems is very important Much of the system’s functionality encapsulated in the software Changing/upgrading the system by changing software Hardware is kept the same Reduced production cost Upgrading is possible even remotely

24. What led the widespread use of Hw / Sw approach? Providing easy maintenance upgrades Same mechanism in previous slide allows bugs to be resolved through changing software Reduces the expensive repairs that involves hardware modifications

25. What led the widespread use of Hw / Sw approach? Improving mechanical performance Finer degree of control is essential for any electromechanical system It can prevent excessive wear, provide better control, diagnostics and even compensate for wear and tear E.g. An engine control system that acts on input like temperature, accelerator pedal position and so on Configurable for different environments Third parties can boost performance by changing control software Can void manufacturer warranty Can cause shorter lifespan Even infringe manufacturer's intellectual property rights See in next slide about this

26. What led the widespread use of Hw / Sw approach? Protection of intellectual property A completely hardware based design is easy to reverse engineer and reproduce Identify the chips and connections and understand the design But software is not that easy to copy Can be burnt into the on-chip memory – effectively impossible to access

27. What led the widespread use of Hw / Sw approach? Replacement for analog circuits Analog processing is simpler while digital processing is more complex Digital processing does not suffer from component ageing/drift They have high noise immunity The ability to dynamically modify the coefficients

28. Hardware/Software Approach – Limitations Performance Serial processing, only one micro step at a time Execution overheads Only once task (SISD) at any given time Resource utilization Small systems may not need all resources available in the processor Many resources may remain un-used Efficiency Hardware design may be sub-optimal for a given task Higher power consumption–especially by unused resources Security risks Some one could modify the software ? Cost May not be cost effective when large quantities are needed

29. In spite of these limitations – Hw / Sw based designs have invaded the consumer electronic market ..and the list goes on and on.

30. Inside the embedded system Processor Memory Peripherals Software Algorithms

31. Inside the embedded system Processor Can it provide the processing power needed by the system? Most frequently, tasks are underestimated in size/complexity Benchmarks do not represent real loads In simulations, execution takes place out of cache memory but real programs do not fit the cache Software overheads for high level languages, operating systems, interrupts Cost System cost, not the processor in isolation Power consumption Software tools and component availability

32. Inside the embedded system Memory Consumption is heavily influenced by the software design Software design is also influenced by the memory available Provides storage for the software Non-volatile memory On-chip ROM or EPROM Can store full software or initiation routine (bootstrap program) Provides storage for the data Program variables, intermediate results, status information RAM is volatile, faster and expensive

33. Inside the embedded system Peripherals Inputs/Outputs Sensors, actuators, displays, other signals E.g. motor controller  given input of current speed, and power, it produces PWM signal hence rotation displaying the speed Binary outputs Simple external pins whose logic sate can be either 1 or 0 Can be grouped in to parallel ports Serial outputs Uses one or two pins in serial mode Les complex to connect but complicated to program Parallel port looks very similar to a memory location A serial port has to have data loaded to a register and needs a start command at least

34. Inside the embedded system Peripherals (contd.) Analog values Processors operate in digital domain Natural world tends to orientate to analog values Interfacing is necessary Displays Time derived outputs Timers and counters

35. Inside the embedded system Software Initialization and configuration Operating system/run-time environment Application software Error handling Debug and maintenance support

36. Inside the embedded system Algorithms Key constituents of the software that makes an embedded system works the way it does Defining and implementing the correct algorithm is critical Processing power needed, speed, accuracy

37. In class State the characteristics of an Embedded System. What are the challenges you face when solving a problem implementing an Embedded System? What are the components you would find inside an ES? State at least two benefits and limitations of using a hardware/software approach.