Embedded Systems. Arduino. Labs. Labs 1/17/2019. CSE 362: Computer Design Lecture 2: Embedded Systems

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1 Embedded Systems CSE 362: Computer Design Lecture 2: Embedded Systems Cynthia Taylor University of Illinois, Chicago August 31, 2017 Microchips used in a non computer setting Inside some other device Frequently directly control physical/electrical aspects of a device Examples: Why Are Embedded Systems Interesting for Computer Design? Highly constrained Less memory, lower power, slower Simpler No OS! No memory management, syscalls... Direct electrical control over attached components Arduino Open source hardware Programmed in C++ Huge number of libraries, tutorials, demos... Good illustration of basic principles of computer design Labs Designed to give you a feel for working with embedded systems Working with input and output (Lab 1 6) Communicate with computers, arduino, I/O (Lab 7 9) Labs Show up during your lab time (9am 3pm) Demonstrate your working lab solution to a TA Start working on next lab, get help, etc Upload your code to blackboard by 11:59pm PLEASE START THE LABS BEFORE THE DAY THEY ARE DUE 1

2 Questions on Labs? Project Groups of 2 4 Number people x requirement If you're group of 3 people, then you need to use 3 arduinos and a total of 6 different external devices Make use of an arduino (or similar) microcontroller Utilize at least two different external devices (16x2 display, LEDs, pushbuttons, touch sensors, etc) Utilize some communication mechanism (ethernet, bluetooth, serial, etc) Involve some original work Project Can use internet tutorials, libraries, code, etc You must document what you use Must involve some original work Description on web page (soon) Project Deliverables Project idea 1 paragraph per idea 2/1 Determine Team & 2 page writeup 4 page writeup 5 min Presentation of project 4/26 Final report pages Project Checkout on campus Questions on Labs or Projects? Basic Digital Control Send electricity to an output device, it turns on! Input devices control whether electricity continues to flow through a circuit 2

3 Embedded System: Output Embedded System: Input Connect I/O to programmatically controlled electrical contacts Turn on electricity to the LED, the LED lights up! Can programmatically turn on the LED You will do this in Lab 1 Create a circuit with an output device on it Programmatically check whether or not electricity is flowing through the circuit Digital versus Analog Arduino Uno Analog: the actual voltage value has semantic meaning Photoresistors Temperature sensors Digital: We treat the voltage as either 1 (HIGH) or 0 (LOW) LEDs Buttons Switches You will work with analog I/O in labs 4 and 5 6 analog pins 14 digital pins USB for power/talking to your computer Runs at 5 V This Arduino code // the setup function runs once when you press reset or power the board void setup() { // initialize digital pin LED_BUILTIN as an output. pinmode(led_builtin, OUTPUT); // the loop function runs over and over again forever void loop() { digitalwrite(led_builtin, HIGH); // turn the LED on digitalwrite(led_builtin, LOW); // turn the LED off A. Turns an LED on once and off once B. Makes an LED blink forever C. Does something else Setup Function // the setup function runs once when you press reset or power the board void setup() { // initialize digital pin LED_BUILTIN as an //output. pinmode(led_builtin, OUTPUT); Runs exactly once, when arduino is powered on or reset Set pins you will use to input or output Initialize any variables you will use 3

4 Loop Function // the loop function runs over and over again forever void loop() { digitalwrite(led_builtin, HIGH); // turn the //LED on (HIGH is the voltage level) // wait for //a second digitalwrite(led_builtin, LOW); // turn the // LED off by making the voltage LOW // wait for // a second Runs in a loop forever Where most of your code should go Microcontrollers and Time Input and output change over time One way we represent systems over time is using timing diagrams Select the correct output for Y Select the timing diagram for the LED 0s 1s 2s 3s 5s 6s Y = J && K J A K A B B C C D E None of the above // the loop function runs over and over again forever void loop() { digitalwrite(led_builtin, HIGH); // turn the LED on (HIGH is the voltage level) digitalwrite(led_builtin, LOW); // turn the LED off by making the voltage LOW Enabling Microcontrollers: Transistors Silicon Semiconductor Smaller, cooler, and more reliable than vacuum tubes Still relatively large By adding different materials, can change its conductive properties Conductor Insulator Areas that can conduct or insulate under different conditions 4

5 Integrated Circuits Chip Design 1,400,000,000 transistors in Intel s Quad core Ivy Bridge chip Way too complicated for any one person to design Electronic circuits are printed on silicon by machines Small! Cheap! Fast! Low Power! People design functionality, Computer designs/optimizes actual chip layout Logical units may not be physically adjacent Moore s Law Tells Us Moore s Law A. Computers get twice as fast every 18 months B. The number of transistors on a chip doubles every 18 months C. CPUs are going to get faster and cheaper forever, everything is awesome Processor Performance with Time Intel Specint2000 Alpha Sparc Mips HP PA Power Trends Performance Power PC AMD In modern transistor technology Power Capacitive load Voltage 2 Frequency Year of introduction 5

6 The Power Wall Power Capacitive load Voltage Frequency Power: How expensive your computer is to run/how fast your phone runs out of batteries amount of energy transferred (joules/watts) Capacitive load: Electricity to change transistor values. Controlled by transistor technology, connections between transistors. Frequency: The clock speed of the chip (instructions per second) Voltage: Voltage at which we run the chip 2 How did clock rate stay steady while power decreases? Power Capacitive load Voltage 2 A. They are not dependent on each other. Frequency B. Voltage went down while Clock Speed increased. C. Capacitive Load went down while Clock Speed increased. Can we just keep lowering voltage for faster computers? Lowering voltage makes transistors leak power Means you re not actually saving power Can cause incorrect computations Which of these is a challenge for powering computers? A. Battery life B. Cooling the computer C. Amps of wall power in homes D. A and B E. All of the above Cooling CPUs get HOT Switching those little transistors on and off takes power! Power turns into heat. All is not lost If we can t run a single instruction faster, what if we run a bunch of instructions at once? If they get too hot, they will burn out Can no longer efficiently cool number of transistors on a chip Intel Quad Core Intel Nehalem Intel: 80 core prototype 6

7 Reading Next lecture: Number Systems Review zybook (Due Wednesday by 11:59pm) NO CLASSES MONDAY (MLK Day) but Chapter 1 reading still due by Monday 11:59pm. Challenge Assignments Due by 11:30pm soon after Reading Assignment is Due. 7