“Politehnica” University of Timişoara Facult y of Automation and Computers

1. “Politehnica” University of TimişoaraFacultyof Automation and Computers Advanced Embedded Systems Master Computer Engineering Program, 1st year Lecturer: prof. dr. ing. Mircea POPA

2. Advanced Embedded Systems Lecture 1 Embedded Systems – General Features

3. Advanced Embedded Systems • Content: • Introduction • General features • Design goals and methodologies • Specifications • Reliability, safety and security • Embedded systems hardware • Input/ outputs • CPU • Interrupts • Embedded systems software • Operating systems • Real time process scheduling • Programs • Multiprocessors in embedded systems • Hardware/ software codesign • Validation of embedded systems

4. Advanced Embedded Systems • References: • P. Mawerdell, Embedded System Design; Springer, 2006 • W. Wolf, High-Performance Embedded Computing;Morgan Kaufmann Publishers, 2007 • R. Zurawski, Embedded Systems Handbook;CRC, 2005

5. Advanced Embedded Systems 1. Definitions and connections • There are several definitions; • Dortmund definition: • Embedded systems are information processing systems that are embedded into a larger product; • Berkeley definition: • Embedded software is software integrated with physical processes; • My definition: • Embedded Systems is a field of the computer engineering domain based on user programmable logic circuits, oriented on real – time applications; • User programmable logic circuits: microprocessors, microcontrollers, DSPs; • Microprocessors: for general purpose applications; • Microcontrollers: for real – time applications; • DSPs: for digital processing of analog signals (used especially in audio and video areas);

6. Advanced Embedded Systems • ESs are destined to one application or a family of applications; • They may contain a microcomputer but usually are self - stating systems included in the devices they control; • The basic circuit is the microcontroller; • ESs are support for: ubiquitous computing, pervasive computing, ambient intelligence – they define the “Post PC era”; • The influence of ESs and communication technologies on ubicom:

7. Advanced Embedded Systems 2. Common characteristics of ESs • Frequently, ESs are connected to the external world through sensors, for monitoring the environment and actuators, for controlling the environment; • Dependability: • The main reason is that ESs are directly connected to the external world and directly and immediately influences it; • They have to be dependable because in many cases are safety – critical (e.g. nuclear power plants, cars, trains, airplanes etc.) • Dependability means: • Reliability: the probability that a system will not fail; • Maintainability: the probability that a failing system can be repaired within a certain time; • Availability: the probability that a system is available; • Safety: is the property that a failing system will not cause any harm; • Security: the property that authentic communication is guaranteed and data are confidential unless otherwise specified;

8. Advanced Embedded Systems • Efficiency: metrics for evaluating it: • Energy: many ESs are mobile being powered by batteries; battery technology improves at a lower rate than the increasing rate of the computational requirements so the available electrical energy must be used very efficiently; not so important for static ESs unless the case when power supplies are not available; • Code size: ESs don’t have hard disks for storing the code so it must be memorized in the system; the internal memory have limited capacity and it must be very efficiently used, meaning the code size should be minimized; • Run time efficiency: the minimum amount of hardware resources should be used for implementing the required functionality; parameters of the hardware (e.g. clock frequencies and supply voltages) should be optimized; • Weight: being portable, many ESs must have low weight; • Cost: very important for competitiveness on the market, especially when a great number of ESs are needed (e.g. in consumer electronics);

9. Advanced Embedded Systems • Oriented or even dedicated towards a certain application or family of applications: • An ES will run always the same software; • Usually additional programs are not implemented because: • Running additional programs will make the system less dependable; • Running additional programs is only feasible if memory is unused, but unused resources should not exist in efficient systems; • ESs have dedicated user – interfaces: • ESs do not use classical peripherals such as keyboards, mice and monitors; • Instead they use push – buttons, steering wheels, pedals, leds, LCDs, 7 segment dispalys; • Many ESs are hybrid systems: they contain analog and digital parts; the analog parts can be for inputs or outputs and the digital part is for processing and can be for inputs or outputs; frequently the analog part is included in the CPU (microcontroller);

10. Advanced Embedded Systems • Real – time constraints: • Hard real – time constraint: not meeting that constraint can result in a catastrophe (for example if an ES don’t control the brake of a car in a predetermined time); • Soft real – time constraint: not meeting that constraint will result in a loss of the quality provided by the system (for example, in audio or video areas); • ESs have to guarantee system response in worst case; solutions for improving the average performance (e.g. cache memories) or the average delay (e.g. by retransmissions) are not useful; • Reactive systems: • A reactive system is in continuous interaction with its environment and executes at a pace determined by that environment; • Reactive systems can be modeled by automata: they are in a certain state, waiting for an input, and when this comes they execute some computations and pass in a new state and possibly generate an output; they react in the same way for each input.

11. Advanced Embedded Systems • Some differences from general purpose computers: • Human interface: leds, LCDs, cameras, switches, minikeyboards and neither monitors nor keybords; • Simple input/ output devices, no peripheral equipments; • Diagnostic port: for ES + the controlled system, not only for the computing part; • FPGAs, ASICs, analogic hardware for increasing performance or safety; • Software has a fixed function and is specific to the application; a general purpose computer may execute several programs chosen by the user but an ES may execute several programs chosen by the programmer; • Dimensions, power consumption and cost; • Lower speed: PCs are oriented to massive processing applications while ESs are oriented to real – time applications (input/ output rather than processing operations); • Limited capacity for memories: no need for much memory in case of real – time applications.

12. Advanced Embedded Systems 3. Applications areas • Automotive: • 90% of innovation in a car is related to electronics; • ABS, ESP, smart keys, blind angle alert system, tire pressure, … • Many microcontrollers in a car: can be more than 100; are connected in different networks; • Heterogeneous microcontrollers: 8 bit for doors, lights, 16 bit for other of the functions, 32 bit for engine, airbags etc. • Aerospace: • Planes, spatial vehicles; • Flight control, anti – collision, pilot information systems etc. • Dependability is extremely important; • Trains: dependability is extremely important; • Telecommunications: mobile phones contain several microcontrollers; low – power aspects are very important;

13. Advanced Embedded Systems • Medical systems: • Portable monitoring systems; • Artificial eye; • Measurements systems for medical parameters (e.g. the blood pressure); • Military applications: radar, weapons, missiles, navigation etc. • Authentication systems: • Ex.: SMARTpen; it analyses physical parameters (tilt, force, acceleration) while the user is signing; the values are sent to a host and compared with information available about the user allowing to verify both the image of the signature and the way it is produced; • Other examples: finger print sensors, face recognition systems;

14. Advanced Embedded Systems • Robotics: • Mechanical aspects are very important; • A lot of information are sensed and sent to local or central ESs and commands are generated by ESs for moving, artificial voice, image processing etc. • Consumer electronics: all kind of electrical household machines: microwaves, washing machines, refrigerators, audio, video, cameras, phones, garden equipments etc. • Smart buildings: • For snugness, optimization and security; • 2 types: work spaces and homes; • Integration of multimedia devices and put under the control of a PC; • Intelligent lighting systems for minimizing the consume; • The same for HVAC systems; • The accesses in the rooms of a smart building locating a company can be monitored and traced;

15. Advanced Embedded Systems • Industrial equipments: • Automation of processes: • Special machines: carpentry machines, forestry machines etc. • Counting systems on a pipeline; • Calibrating systems; • Welding machines:

16. Advanced Embedded Systems • Toys: LEGO mind storms robotic kit • It is a set including programmable bricks, electric motors, sensors and technical pieces such as gears, axles and beams; • A programmable brick is built around an 8 bit microcontroller which is programmable by downloading a program written on a PC or a MAC, through a RF interface; • Languages: • Lego types: RCX, ROBOLAB • Third party classical: C, C++, Java, Visual Basic etc.

17. Advanced Embedded Systems • Smart sensors: • Cricket sensors: • RF sensors; • Ultrasonic sensors; • Tiny OS; • Powered with batteries or externally; • RS232 interface for being programmed or transferring data; • 2 modes: • Beacon, • Listener; • The time difference between the RF pulse and the ultrasonic pulse indicates the distance among a beacon and a listener; • Applications: space identifiers and position coordinates: the beacons are deployed in a delimited space and they will indicate the position of one or several mobile listeners;

18. Advanced Embedded Systems • MICAz • Atmega 128L microcontroller; • ZigBee RF interface; • MICA2DOT • Same microcontroller; • RF interface;

19. Advanced Embedded Systems 4. Importance of embedded systems • In 2000, 75% of all 32 bit processors were integrated into embedded systems; • In 1996, an average american came into contact with 60 microprocessors/ microcontrollers/ DSPs per day; • Today we carry ESs: cards, mobile phones etc. • A journalist stated in 1995: “… embedded chips form the backbone of the electronics driven world in which we live ,,, they are part of almost everything that runs on electricity.” • A variant of the Moore law shows that: “for many products in the area of consumer electronics the amount of code is doubling every two years” (Vaandrager, 1998); • Classical example: the TV set: 1KB in 1979, 64 KB in 1990, 2 MB in 2000; • ESs are the bricks of the “Post PC era” in which information processing is more and more moving from PCs to ESs;

20. Advanced Embedded Systems 5. Structure • Typically, an ES is made of 5 parts: • CPU; • Memory; • Specific input/ outputs; • Basic software; • Application software; • CPU: microprocessors, microcontrollers, DSPs; • Memory: the ideal situation is when the internal memory is sufficient for avoiding external memories, which may require other circuits too; • Specific input/ outputs: leds, LCDs, … • Basic software: RTOS (for complex ESs, e.g. distributed ESs); simple ESs (e.g. for household appliances) don’t need basic software; • Application software: ensures that the ES works according to the requirements; implements operations like: monitoring, processing, command and control.

21. Advanced Embedded Systems • Example: Atmel AT89C51 (8051) Starter Kit & Serial Port Programmer • Features: • Easy Flash memory programming with the serial port of a computer; • On-board power regulator and power on LED; • Diode for reverse power supply polarity protection; • Use of the same serial port for programming, transmitting and receiving; • Toggling between programming/execution modes with a press of a single switch eliminating the need for any complex changes in the hardware; • Square post headers provide access to all port pins for easy interfacing to external devices; • Built-in LEDs on port to test the bit pattern; • AT89C51RD2 supplied with kit • Built-in 64KB flash memory and 2KB RAM Flash; • Data retention life of more than 10 years; • No special skills required to operate the kit; • Hex file can be downloaded easily with the help of a user friendly FLIP software; • A variety of ATMEL Microcontroller ICs (8051 family, DIP 40 pin with flash memory) are supported by the kit.

22. Advanced Embedded Systems • An other example: WiFi RCM4400W RabbitCore • Features: • At the heart of the RCM4400W WiFi module is the Rabbit 4400 microprocessor, featuring a clock speed of up to 58.98MHz; other features include a true hardware DMA, auxiliary I/O, a quadrature decoder, input capture, GPIO lines shared with up to six serial ports, and four levels of alternate pin functions that include a variable phase PWM; • RabbitCore module running @ 58.98 MHz; • Integrated scalable Wi-Fi/802.11 wireless connectivity; • Serial to WiFi bridge capability; • 512K flash memory; • 512K fast program-execution SRAM; • 512K data SRAM; • Up to 35 general-purpose I/O lines configurable; • 3.3 V I/O lines; • Low-power modes down to 2 kHz; • Small size: 1.84" x 2.85" x 0.50" (47 mm 72 mm 13 mm).

23. Advanced Embedded Systems 6. Educational aspects • The first discipline focused on: • Description of the hardware of classical (uniprocessor) ESs, meaning microcontrollers, memories, typical input/ outputs, internal peripherals; • Description of the software of classical ESs, meaning languages (assembler and C); • Description of classical applications, such as the automotive area and the Embedded Internet; • This discipline treats the ESs at a higher level, focusing on the design aspects of ESs, meaning: • General requirements; • Specification languages; • Scheduling and validation techniques; • Embedded operating systems; • General hardware of ESs; • Distributed ESs; • Hardware/ software codesign;

24. Advanced Embedded Systems • A simplified design information flow: • The starting point is the application; standard hardware and software components must be considered and reused whenever possible; • The application must be put in specifications; they are the starting point of the design; • Design activities mean mapping operations to concurrent tasks, high – level transformations (such as loop transformations), mapping of operations to either hardware or software, design space exploration, compilation and scheduling;

25. Advanced Embedded Systems • Special purpose hardware may be necessary; • Compilation can be done with standard compilers but they are not optimized for embedded processors; as a consequence compiler techniques should be applied for obtaining efficiency; • Scheduling is possible after obtaining the binary code for each task; • Finally, software and hardware descriptions can be merged, obtaining a complete description of the design; this is the input for the fabrication; • It is necessary to validate and evaluate the design at each phase; there are not other guarantees for the correctness of the design; • The validation consists of checking intermediate and final design descriptions against other descriptions; • Different parameters must be evaluated during the design: performance, dependability, energy consumption etc. • The design activities must follow the design information flow presented but not always in a linear way; • In practice, some design activities may be repeated; it may become necessary to return to the specifications, or to consider other components etc.