Embedded System Basics and Application PDF

EMBEDDED SYSTEM BASICS AND APPLICATION  INTRODUCTION What is a system? A system is a way of working, organizing or doing one or many tasks according to a fixed plan, program or set of rules. A system is also an arrangement in which all its units assemble and work together a...

EMBEDDED SYSTEM BASICS AND APPLICATION  INTRODUCTION What is a system? A system is a way of working, organizing or doing one or many tasks according to a fixed plan, program or set of rules. A system is also an arrangement in which all its units assemble and work together according to the plan or program. 2  SYSTEM EXAMPLES WATCH It is a time display SYSTEM Parts: Hardware, Needles, Battery, Dial, and Strap Rules 6.All needles move clockwise only 7.A thin needle rotates every second 8.A long needle rotates every minute 9.A short needle rotates every 3  SYSTEM EXAMPLES WASHING MACHINE It is an automatic clothes washing SYSTEM Parts: Status display panel, Switches & Dials, Motor, Power supply & control unit, Inner water level sensor and solenoid valve. Rules 5.Wash by spinning 6.Rinse 7.Drying 8.Wash over by 4  EMBEDDED SYSTEM  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.  Industrial machines, consumer electronics, agricultural and processing industry devices, automobiles, medical equipment, cameras, digital watches, household appliances, airplanes, vending machines and toys, as well as mobile devices, are possible locations for an embedded system.  COMPUTER HARDWARE A Microprocessor A Large Memory (Primary and Secondary) (RAM, ROM and caches) Input Units (Keyboard, Mouse, Scanner, etc.) Output Units (Monitor, printer, etc.) Networking Units (Ethernet Card, Drivers, etc.) I/O Units (Modem, Fax cum Modem, etc.) 7 COMPONENTS OF EMBEDDED SYSTEM It has Hardware Processor, Timers, Interrupt controller, I/O Devices, Memories, Ports, etc. It has main Application Software Which may perform concurrently the series of tasks or multiple tasks. It has Real Time Operating System (RTOS) RTOS defines the way the system work. Which supervise the application software. It sets the rules during the execution of the application program. A small scale embedded system may not need an RTOS. 8 EMBEDDED SYSTEM HARDWARE 9 EMBEDDED SYSTEM CONSTRAINTS An embedded system is software designed to keep in view three constraints: – Available system memory – Available processor speed – The need to limit the power dissipation When running the system continuously in cycles of wait for events, run, stop and wakeup. 03.01.09 10  What makes embedded systems different? Real-time operation size cost time reliability safety energy security 03.01.09 11  CLASSIFICATIONS OF EMBEDDED SYSTEM Small Scale Embedded System Medium Scale Embedded System Sophisticated Embedded System 03.01.09 12 SMALL SCALE EMBEDDED SYSTEM Single 8 bit or 16bit Microcontroller. Little hardware and software complexity. They May even be battery operated. Usually “C” is used for developing these system. The need to limit power dissipation when system is running continuously. Programming tools: Editor, Assembler and Cross Assembler 13  MEDIUM SCALE EMBEDDED SYSTEM Single or few 16 or 32 bit microcontrollers or Digital Signal Processors (DSP) or Reduced Instructions Set Computers (RISC). Both hardware and software complexity. Programming tools: RTOS, Source code Engineering Tool, Simulator, Debugger and Integrated Development Environment (IDE). 14  SOPHISTICATED EMBEDDED SYSTEM Enormous hardware and software complexity Which may need scalable processor or configurable processor and programming logic arrays. Constrained by the processing speed available in their hardware units. Programming Tools: For these systems may not be readily available at a reasonable cost or may not be available at all. A compiler or retargetable compiler might have to br developed for this. 15  PROCESSOR A Processor is the heart of the Embedded System. For an embedded system designer knowledge of microprocessor and microcontroller is a must. Two Essential Units: Operations Control Unit (CU), Fetch Execution Unit (EU) Execute 03.01.09 16  VARIOUS PROCESSOR 1. General Purpose processor (GPP) Microprocessor Microcontroller Embedded Processor Digital signal Processor 2. Application Specific System Processor (ASSP) 3. Multi Processor System using GPPs 03.01.09 17  MICROPROCESSOR A microprocessor is a single chip semi conductor device also which is a computer on chip, but not a complete computer. Its CPU contains an ALU, a program counter, a stack pointer, some working register, a clock timing circuit and interrupt circuit on a single chip. To make complete micro computer, one must add memory usually ROM and RAM, memory decoder, an oscillator and a number of serial and parallel ports. 03.01.09 18  HISTORY OF MICROPROCESSOR 1st Generation (4 bit processors) 4004 and 4040 4 bit in early 1970 by Intel (Integrated Electronics) 2nd Generation (8 bit processors) 8008 and 8080 8 bit in 1974 Intel with +5 V Input supply 8080  8085 8 bit 3rd Generation (16 bit processors) 8086 16 bit. Same as 8086, the 8088 introduced 8088 has only 8 bit data bus (This made it easier to interface to the common 8 bit peripheral devices available at the time) Followed by: The 80186 & 80286 (16 bit processor), the 80386 & 80486 (a 32 bit processor), leading to the Pentium range of microprocessors (64 bit processors) available today. The 80x86 and Pentium processors have all been designed for use in personal computer type applications and have large memory maps. 03.01.09 19  VARIOUS MICROPROCESSORS Intel Zilog 4004, 4040 8080, 8085 Z80, Z180, eZ80 8086, 8088, Z8, eZ8 80186, 80188 80286, 80386 x86-64 Motorola 6800 6809 68000 G3, G4, G5 03.01.09 20  MICROCONTROLLER A microcontroller is a functional computer system-on-a-chip. It contains a processor, memory, and programmable input/output peripherals. Microcontrollers include an integrated CPU, memory (a small amount of RAM, program memory, or both) and peripherals capable of input and output. 21 VARIOUS MICROCONTROLLERS INTEL 8031,8032,8051,8052,8751,8752 PIC 8-bit PIC16, PIC18, 16-bit DSPIC33 / PIC24, PIC16C7x Motorola MC68HC11 22 23 Sensors Sensor A sensor is a device which converts the physical parameter of a quantity into corresponding electrical output. It is such a device that is used to detect the variation occurring in the system and send to the main device which can be a computer. It needed certain types of devices to operate on Its practical installation is in lifts of shopping malls’ lamps operation. There is still the use of potentiometer and resistance to control the analog sensors The device used to explain the composition of different chemical substances like gases, fluids are called a chemical sensor The chemical sensor tells the quantity of material in the form of signal and then converted in the values An example of a sensor is a proximity sensors, Magnetic sensors, Accelerometer sensors, Light sensors, etc. What is an IR Sensor? IR sensor is an electronic device, that emits the light in order to sense some object of the surroundings. An IR sensor can measure the heat of an object as well as detects the motion. Usually, in the infrared spectrum, all the objects radiate some form of thermal radiation. These types of radiations are invisible to our eyes, but infrared sensor can detect these radiations. Infrared (IR) has wavelengths λ between 780 nm and 1 mm, which corresponds to a frequency range from 300 GHz to 400 THz. What is an IR Sensor? The emitter is simply an IR LED (Light Emitting Diode) and the detector is simply an IR photodiode. Photodiodes are designed to work in reverse bias condition. Typical photodiode materials are Silicon, Germanium and Indium gallium arsenide. Photodiode is sensitive to IR light of the same wavelength which is emitted by the IR LED. When IR light falls on the photodiode, the resistances and the output voltages will change in proportion to the magnitude of the IR light received. There are five basic elements used in a typical infrared detection system: an infrared source, a transmission medium, optical component, infrared detectors or receivers and signal processing. Infrared lasers and Infrared LED’s of specific wavelength used as infrared sources. The three main types of media used for infrared transmission are vacuum, atmosphere and optical fibers. Optical components are used to focus the infrared radiation or to limit the spectral response. Types of IR Sensor There are two types of IR sensors are available and they are, Active Infrared Sensor Passive Infrared Sensor Active Infrared Sensor Active infrared sensors consist of two elements: infrared source and infrared detector. Infrared sources include the LED or infrared laser diode. Infrared detectors include photodiodes or phototransistors. The energy emitted by the infrared source is reflected by an object and falls on the infrared detector. Active Infrared Sensor Active infrared sensors work with radar technology and they both emit and receive infrared radiation. This radiation hits the objects nearby and bounces back to the receiver of the device. Through this technology, the sensor can not only detect movement in an environment but also how far the object is from the device. Passive Infrared Sensor Passive infrared sensors are basically Infrared detectors. Thermal infrared sensors use infrared energy as the source of heat. Thermocouples, pyroelectric detectors and bolometers are the common types of thermal infrared detectors. Quantum type infrared sensors offer higher detection performance. It is faster than thermal type infrared detectors. The photo sensitivity of quantum type detectors is wavelength dependent. A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors. PIR sensors are commonly used in security alarms and automatic lighting applications. IR Sensor Working Principle There are different types of infrared transmitters depending on their wavelengths, output power and response time. An IR sensor consists of an IR LED and an IR Photodiode, together they are called as PhotoCoupler or OptoCoupler. IR Transmitter or IR LED Infrared Transmitter is a light emitting diode (LED) which emits infrared radiations called as IR LED’s. Even though an IR LED looks like a normal LED, the radiation emitted by it is invisible to the human eye. IR Sensor Working Principle IR Receiver or Photodiode Infrared receivers or infrared sensors detect the radiation from an IR transmitter. IR receivers come in the form of photodiodes and phototransistors. Infrared Photodiodes are different from normal photo diodes as they detect only infrared radiation. IR Sensor Working Principle Different types of IR receivers exist based on the wavelength, voltage, package, etc. When used in an infrared transmitter – receiver combination, the wavelength of the receiver should match with that of the transmitter. The emitter is an IR LED and the detector is an IR photodiode. The IR photodiode is sensitive to the IR light emitted by an IR LED. The photo-diode’s resistance and output voltage change in proportion to the IR light received. This is the underlying working principle of the IR sensor.  IR Sensor Working Principle When the IR transmitter emits radiation, it reaches the object and some of the radiation reflects back to the IR receiver. Based on the intensity of the reception by the IR receiver, the output of the sensor defines. Applications of IR Sensor IR sensors use in various projects and also in various electronic devices. They all are as follow, Night Vision Devices Applications of IR Sensor An Infrared technology implemented in night vision equipment if there is not enough visible light available to see unaided. Night vision devices convert ambient photons of light into electrons and then amplify them using a chemical and electrical process before finally converting them back into visible light. Radiation Thermometers Applications of IR Sensor IR sensors uses in radiation thermometers to measure the temperature depend upon the temperature and the material of the object and these thermometers have some of the following features Measurement without direct contact with the object Faster response Easy pattern measurements Infrared Tracking An Infrared tracking or Infrared homing, is a missile guidance system which operates using the infrared electromagnetic radiation emitted from a target to track it. Ultrasonic Sensor In industrial applications, an ultrasonic detection used to detect hidden tracks, discontinuities in metals, composites, plastics, ceramics, and for water level detection. For this purpose, the laws of physics which are indicating the propagation of sound waves through solid materials have been used since ultrasonic sensors using sound instead of light for detection. Ultrasonic sensors work by emitting sound waves at a frequency which is too high for humans to hear. Ultrasonic Sensor Working Principle An ultrasonic sensors are excellent at suppressing background interference. Virtually all materials which reflect sound can be detected, regardless of their color. Even transparent materials or thin foils represent no problem for an ultrasonic sensor. micro sonic ultrasonic sensors are suitable for target distances from 20 mm to 10 m. Some of our sensors can even resolve the signal to an accuracy of 0.025 mm. Ultrasonic sensors can see through dust-laden air and ink mists. Even thin deposits on the sensor membrane do not impair its function. Ultrasonic Sensor Working Principle An ultrasonic sensor is an instrument that measures the distance to an object using ultrasonic sound waves. An ultrasonic sensor uses a transducer to send and receive ultrasonic pulses that relay back information about an object's proximity. Ultrasonic Sensor VCC – +5 V supply TRIG – Trigger input of sensor. Microcontroller applies 10 us trigger pulse to the HC- SR04 ultrasonic module. ECHO–Echo output of sensor. Microcontroller reads/monitors this pin to detect the obstacle or to find the distance. GND – Ground Features of an Ultrasonic Sensor Supply voltage: 5V (DC). Supply current: 15mA. Modulation frequency: 40Hz. Output: 0 – 5V (Output high when obstacle detected in range). Beam Angle: Max 15 degrees. Distance: 2 cm – 400 cm. Accuracy: 0.3cm. Communication: Positive TTL pulse. Ultrasonic Sensor Distance Calculation In order to calculate the distance between the sensor and the object, the sensor measures the time it takes between the emission of the sound by the transmitter to its contact with the receiver. The formula for this calculation is D = ½ T x C (where D is the distance, T is the time, and C is the speed of sound ~ 343 meters/second). For example, if a scientist set up an ultrasonic sensor aimed at a box and it took 0.025 seconds for the sound to bounce back, the distance between the ultrasonic sensor and the box would be: D = 0.5 x 0.025 x 343 Timing Diagram of Ultrasonic Sensor Timing Diagram of Ultrasonic Sensor First need to transmit trigger pulse of at least 10 us to the HC-SR04 Trig Pin. Then the HC-SR04 automatically sends Eight 40 kHz sound wave and wait for rising edge output at Echo pin. When the rising edge capture occurs at Echo pin, start the Timer and wait for falling edge on Echo pin. As soon as the falling edge captures at the Echo pin, read the count of the Timer. This time count is the time required by the sensor to detect an object and return back from an object. Applications of an Ultrasonic Sensors It uses to avoid and detect obstacles with robots like biped robot, obstacle avoider robot, path finding robot etc. It Used to measure the distance within a wide range of 2cm to 400cm. Used to map the objects surrounding the sensor by rotating it. Depth of certain places like wells, pits etc can be measured since the waves can penetrate through water. Temperature Sensor Temperature sensors are a simple instrument that measures the degree of hotness or coolness and converts it into a readable unit. We all use temperature sensors in our daily lives, be it in the form of thermometers, domestic water heaters, microwaves, or refrigerators. Usually, temperature sensors have a wide range of applications, geotechnical monitoring field, being one of them. A thermometer is the most basic form of a temperature meter that is used to measure the degree of hotness and coolness. Temperature meters are used in the geotechnical field to monitor concrete, structures, soil, water, bridges etc. for structural changes in them due to seasonal variations. What Do Temperature Sensors Do? A temperature sensor is a device that is designed to measure the degree of hotness or coolness in an object. The working of a temperature meter depends upon the voltage across the diode. The temperature change is directly proportional to the diode’s resistance. The cooler the temperature, lesser will be the resistance, and vice-versa. The resistance across the diode is measured and converted into readable units of temperature (Fahrenheit, Celsius, Centigrade, etc.) and, displayed in numeric form over readout units. How Does Temperature Sensor Work? The basic principle of working of the temperature sensors is the voltage across the diode terminals. If the voltage increases, the temperature also rises. There are also temperature sensors that work on the principle of stress change caused by changes in temperature. In a vibrating wire temperature meter, dissimilar metals have different linear coefficients of expansion. It mainly consists of a magnetic stretched wire of high tensile strength with two ends fixed to any dissimilar metal so that any temperature change will directly affect the tension in the wire and its natural vibration frequency. The dissimilar metal can be made from aluminum since it has a larger linear expansion coefficient than steel. When the conversion of the temperature signal into frequency occurs, the very same read-out unit that is used for other vibrating wire sensors can also be utilized in the monitoring of temperature also. The specially built vibrating wire sensor is the one that senses the temperature change and then the temperature change is converted into an electrical signal which is then transmitted to the read out the unit as a frequency. Temperature Sensor Components There are three types of components in temperature sensors. There are essential components of a temperature sensor including extension cables and wires sensing elements thermocouple Types Negative Temperature Coefficient (NTC) Thermistors Resistance Temperature Detectors (RTDs) Thermocouples Semiconductor-Based Sensors 1. Negative Temperature Coefficient (NTC) thermistor A thermistor is a thermally sensitive resistor that exhibits a continuous, small, incremental change in resistance correlated to variations in temperature. An NTC thermistor provides higher resistance at low temperatures. As temperature increases, the resistance drops incrementally. Small changes reflect accurately due to large changes in resistance per °C. The output of an NTC thermistor is non-linear due to its exponential nature; however, it can be linearized based on its application. The effective operating range is -50 to 250 °C for glass encapsulated thermistors or 150°C for standard thermistors. 2. Resistance Temperature Detector (RTD) A resistance temperature detector, or RTD, changes the resistance of the RTD element with temper ature. It has great stability, accuracy and repeatability. The resistance tends to be almost linear with temperature, the higher the temperature, the larger the resistance. An RTD consists of a film or, for greater accuracy, a wire wrapped around a ceramic or glass core. Platinum makes up the most accurate RTDs while nickel and copper make RTDs that are lower cost; however, nickel and copper are not as stable or repeatable as platinum. Platinum RTDs offer a highly accurate linear output across -200 to 600 °C but are much more expensive than copper or nickel. 3. Thermocouples A thermocouple consists of two wires of different metals electrically bonded at two points. The varying voltage created between these two dissimilar metals reflects proportional changes in temperature. Thermocouples are nonlinear and require a conversion with a table when used for temperature control and compensation, typically accomplished using a lookup table. Accuracy is low, from 0.5 °C to 5 °C but thermocouples operate across the widest temperature range, from -200 °C to 1750 °C. 4. Semiconductor-based temperature sensors A semiconductor-based temperature sensor is usually incorporated into integrated circuits (ICs). These sensors utilize two identical diodes with temperature-sensitive voltage vs current characteristics that are used to monitor changes in temperature. They offer a linear response but have the lowest accuracy of the basic sensor types. These temperature sensors also have the slowest responsiveness across the narrowest temperature range (-70 °C to 150 °C). Temperature Sensors in Control and Compensation Circuits To use a temperature sensor in a control or compensation circuit, the detection circuit must provide an output in a usable format. For analog circuits, the output is usually a resistance. For digital control and compensation, the measurement needs to be converted to a digital format. How Does Temperature Sensor Work? The frequency, which is proportional to the temperature and in turn to the tension ‘σ’ in the wire, can be determined as follows: f = 1/2 [σg/ρ] / 2l Hz Where: σ = tension of the wire g = acceleration due to gravity ρ = density of the wire l = length of wire Applications of Temperature Sensors Industrial Applications Temperature sensors are utilized to monitor various environments and machinery, power plants, and manufacturing. Temperature sensors are used to measure water temperatures in reservoirs and boreholes. They can also be used to interpret temperature-related stress and changes in volume in dams. Temperature sensors are also utilized in the study of the temperature effect on other installed instruments.  Medical Applications Temperature sensors are utilized in the monitoring of patients, in medical devices, in thermodilution, in humidifiers, gas analysis, cardiac catheters, ventilator flow tubes, and dialysis fluid temperature. Uses in Motorsports Temperature sensors are used for measuring inlet air temperature, exhaust gas, engine temperature, and oil temperature. Domestic Appliances Temperature sensors are used in kitchen appliances (ovens, kettles, etc.) and also in white goods. Benefits of Temperature Sensors The benefits of temperature sensors include: Temperature sensors are precise, extremely reliable, and have a low cost. Temperature sensors are suitable for both embedded and surface applications. They provide low thermal mass resulting in a fast response time. The vibrating wire temperature sensor is completely interchangeable; all sensors can be read by one indicator. Temperature sensors are available with indicators for direct display of temperature. Temperature probes exhibit excellent hysteresis and linearity. The technology of the vibrating wire ensures long term stability, easy and quick readout. Temperature sensors perfectly suit remote scanning, reading, and data logging. What Is Arduino? Arduino is an open source programmable circuit board that can be integrated into a wide variety of makerspace projects both simple and complex. This board contains a microcontroller which is able to be programmed to sense and control objects in the physical world. It consists of both a microcontroller and a part of the software or Integrated Development Environment (IDE) that runs on your PC, used to write & upload computer code to the physical board. By responding to sensors and inputs, the Arduino is able to interact with a large array of outputs such as LEDs, motors and displays. Because of it’s flexibility and low cost, Arduino has become a very popular choice for makers and makerspaces looking to create interactive hardware projects. Arduino was introduced back in 2005 in Italy by Massimo Banzi as a way for nonengineers to have access to a low cost, simple tool for creating hardware projects. Types The boards with the name Arduino on them are the official boards but there are also a lot of really great clones on the market as well. One of the best reasons to buy a clone is the fact they are generally less expensive than their official counterpart. Adafruit and Sparkfun for example, sell variations of the Arduino boards which cost less but still have the same quality of the originals. Another factor to consider when choosing a board is the type of project you are looking to do. For example, if you want to create a wearable electronic project, you might want to consider the LilyPad board from Sparkfun. The LilyPad is designed to be easily sewn into e-textiles and wearable projects. If your project has a small form factor, you might want to use the Arduino Pro Mini which has a very small footprint compared to other boards. 1. RESET 2. AREF 3. GND 4. Dig I/O 5. PWM 6. USB 7. TX/RX 8. ATMEGA 9. Power LED Indicator 10.Voltage regulator 11.DC power 12.3.3 V 13.5 V 14.GND 15.ANALOG How To Program Arduino Once the circuit has been created on the breadboard, you’ll need to upload the program (known as a sketch) to the Arduino. The sketch is a set of instructions that tells the board what functions it needs to perform. An Arduino board can only hold and perform one sketch at a time. The software used to create Arduino sketches is called the IDE which stands for Integrated Development Environment. The software is free to download and can be found at https://www.arduino.cc/en/Main/Software Every Arduino sketch has two main parts to the program: void setup() – Sets things up that have to be done once and then don’t happen again. void loop() – Contains the instructions that get repeated over and over until the board is turned off.