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Embedded systems ... 6 Embedded Systems Project First Deadlines Groups formation: For the embedded systems project 3-4 students/group For the major project in electronics 4-5 students/group

Aug 26, 2020

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  • Embedded systems

    Exercise session 1a

    Introduction and project presentation

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    Who am I?

    Michaël Fonder ● PhD candidate and teaching assistant

    My research in two words ● Field : computer vision and deep learning ● Topic : Automate drone flights by using a single monocular camera

    Link with the embedded system course? ● Solid experience in embedded programming (mainly for drone applications)

    What I’ll do for you ● Give exercise and lab sessions for the embedded system course ● Supervise your embedded systems project or major project in electronics

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    In practice

    Contact ● Mail : [email protected] ● Office : 1.82a, Montefiore ● Website for the exercise sessions and the project :

    http://www.montefiore.ulg.ac.be/~mfonder/INFO0064/

    Today ● Project presentation ● Overview of technologies available for your project ● Basic reminders in electricity

    http://www.montefiore.ulg.ac.be/~mfonder/INFO0064/

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    About Exercise Sessions The exercise session will have two main objectives:

    ● Providing you with practical knowledges to achieve your project ● Making exercises about notions seen during the theoretical course

    Sessions about the project During the sessions about the project, we will cover the following points: ● Detailed review of all the important modules of the PIC16F1789; ● Presentation of useful common electronic components; ● Presentation of useful simple circuits blocks; ● Introduction to the rules of electronic circuit design.

    Lab sessions Some exercise sessions are replaced by mandatory lab sessions. Lab sessions are there to give you a first hand-on experience on microcontroller-programming and circuit design.

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    Embedded Systems Project Aim Design, realisation and programming of an embedded circuit. The precise subject (the type of circuit, its purpose,...) is left as a choice for each group but some requirements have to be fulfilled. Those requirements are : ● The necessity to have real-time constraints and concurrent tasks; ● The necessity to design and implement the electronic circuit needed to make your

    project meet its goal in practice; ● The necessity to use a real-time computing platform (e.g. a microcontroller) to

    implement the logical part of the project.

    Concretely ● Group of 3 or 4 students ● Several intermediate mandatory deadlines (see website for detailed schedule) ● 3 preparation labs

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    Embedded Systems Project First Deadlines Groups formation:

    ● For the embedded systems project 3-4 students/group ● For the major project in electronics 4-5 students/group ● Ideally today at the end of the session ● Or before next week after the exercise session by mail

    Project ideas presentation ● For the embedded systems project Fri Oct 18 during lunch time? ● For the major project in electronics Mon Oct 7 2pm

    Present a few slides which describe your project and how you plan to implement it. The aim of this presentation is to assess the feasibility of your idea based on our experience and to guide you toward something more adapted to the awaited level if necessary.

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    Embedded Systems Project Typical Workflow

    1) System specification and constraints ⚫ What your circuit should achieve ⚫ Your project definition

    2) Define a global solution ⚫ Find ways to achieve the specifications ⚫ Choice of sensors, actuators and other important components

    3) Conceive an electronic schematic which meets specifications ⚫ Find all the components required for your circuit to work and interconnect them properly

    4) Test and validate each critical component individually 5) Complete circuit prototype realisation and tests (return to step 2 if needed) 6) Design and realisation of a printed of a Printed Circuit Board (PCB) (not

    mandatory)

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    Practical Notes for the Project Material ● We will lend you a toolbox containing the cables needed to use the devices of the

    r100 lab and some basic components required to start the project immediately. All the content of this toolbox will have to be handled back at the end of the year for your project to be evaluated. Missing parts will have to be repaid!

    ● You will have a small budget to buy additional components to complete your circuit.

    Advice ● The project combines electronics, informatics and a small part of signal processing.

    All of those parts are important for the good completion of your project. So take care of each of them.

    ● Practical advice will be given during the exercises sessions and in feedbacks. Ignoring them will certainly make you lose time and maybe points at the end of your project. So, for your own good, pay attention and listen to what is said!

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    Microcontrollers : First insight “So, the project revolves around microcontrollers… But what are they?” Microcontrollers (MCU) are small on-chip computers with a series of input and output pins. They contain at least all the components required to run a basic embedded program. They often include additional modules which ease their interfacing with the outer world.

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    Microcontroller example : PIC16F1789 Microchip PIC16F1789 Core Features ● 8-bit words, 16-bit instructions ● Only 49 instructions set ● Up to 8 MIPS (Millions of Instruction Per Second) ● Free programming tool ● Program memory : 16ko ● Data EEPROM : 256 Bytes ● RAM : 2048 Bytes ● Clock frequency up to 32MHz ● 36 general purpose Input/Output pins

    Note ● The program memory holds the binary data to be executed by the microcontroller. ● The EEPROM can be used to write and store data between different power cycles. ● The RAM can be used to write and store data during a single power cycle.

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    Microcontroller Peripheral Modules I

    Additionally to the core computing unit and its digital IO pins, microcontrollers generally embed several independent peripheral modules which ease the interfacing of the MCU with the external world.

    Example of Analog Peripherals ● Analog to Digital Converters (ADC)

    ADC are used to convert an analog voltage into binary data ● Digital to Analog Converters (DAC)

    DAC are used to generate an analog voltage from digital data ● Comparator Modules

    Comparators are used to interface analog circuits by comparing two analog voltages and providing a digital indication of their relative magnitude.

    ● Operational Amplifiers Operational amplifiers are used to process (e.g. amplify and or filter) analog signals.

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    Microcontroller Peripheral Modules II

    Additionally to the core computing unit and its digital IO pins, microcontrollers generally embed several independent peripheral modules which ease the interfacing of the MC with the external world.

    Example of Digital Peripherals ● Timers

    Timers are used to precisely measure elapsed time. ● Pulse Width Modulation (PWM) Signal Generators

    PWM signals are periodic binary signals which stay high during a given proportion of their period and are low everywhere else.

    ● Digital busses and communication lines interfaces (e.g. I2C, EUSART, ...) Digital busses and communication lines are used to transfer binary data between two digital devices according to some given protocols.

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    General considerations

    Microcontrollers are computers. In order to interact with the outer world, they need both inputs (e.g. sensors) and outputs (e.g. actuators). ● Inputs capture information from the world (e.g. microphones, cameras, ...) ● Outputs interact with the world (e.g. motors, pumps, LEDs, ...)

    Analog vs digital Microcontrollers are digital devices which means they work with binary data (0s and 1s).The interface between the microcontroller and the sensors or the actuators is either analog or digital: ● Analog devices transmit or receive their information thanks to a continuous current

    or voltage modulation => need to translate this information from or to binary data ● The microcontroller communicates with other digital devices via busses or

    communication lines

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    Sensor ideas

    Distance ● Ultrasound ● Infra-red

    Input ● Push button ● Keyboard ● Joystick

    Positioning ● Accelerometers ● Gyroscopes ● GPS

    Other ● Microphones ● Pressure ● Serial bus

    Note Each sensor measures a particular information with one particular design => 2 sensors measuring the same information will have a different behaviour depending on the design and the techniques they use

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    Output ideas

    Actuators ● DC motor ● Servo motor ● Valve

    Visual information ● LED or laser ● LCD screen ● VGA signal

    Note Microcontrollers are designed to process and transmit signals, not power => NEVER draw the power required for an output directly on a pin the MCU if their power requirements excess the power limit of the pin

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    Example : Turret of Doom

    Aim Detect movement within a given range and point at the moving points with a laser

    Real-time constraints ● Periodic mapping of the room by using a distance sensor mounted on a servo-motor ● Coordination between head and laser

    Embedded components ● 1 IR distance sensor ● 2 Ser