CMSC838. Tangible Interactive Assistant Professor Computer Science

Transcription

1 CMSC838 Tangible Interactive Computing Week 01 Lecture 02 Jan 29, 2015 Arduino, Sensing, and Processing Human Computer Interaction Assistant Professor Computer Science

2 TODAY S LEARNING GOALS You ll get a taste of a lot of things today, some of which we will go over again ourselves; however, I encourage you to grab components from the HCIL Hackerspace and begin playing and experimenting with concepts, tools, and components to help you learn and reinforce your learning. 1. An overview of the course, course logistics, Maker culture, the Hackerspace, and assignments (especially IA2 & MP1) 2. Arduino basics such as digitalwrite, digitalread, analogwrite, and analogread 3. Light-emitting diode (LED) basics including: LEDs only allow current flow in one direction and that they require current limiting resistors. 4. How to read an LED datasheet and calculate the value of the resistor 5. How to use basic input components like trimpots and basic output components like a speaker 6. How to use the Serial println functionality in Arduino to communicate with your computer and build a simple interactive application in Processing

3 Making the invisible, visible.

4 First, some inspiration: you can do a lot of creative things with simple circuits, a microcontroller, and light

5 Timo Arnall, Jørn Knutsen, & Einar Martinussen, Immaterials: Light Painting WiFi,

6 Timo Arnall, Jørn Knutsen, & Einar Martinussen, Immaterials: Light Painting WiFi

7 Timo Arnall, Jørn Knutsen, & Einar Martinussen, Immaterials: Light Painting WiFi

8 Timo Arnall, Jørn Knutsen, & Einar Martinussen, Immaterials: Light Painting WiFi

9 Kuznetsov et al., Red Balloon, Green Balloon, Sensors in the Sky, UbiComp2011

10 air quality sensor + microcontroller + RGB LED + battery Kuznetsov et al.,

11 Kuznetsov et al., Red Balloon, Green Balloon, Sensors in the Sky, UbiComp2011

12 Helen Evans and Heiko Hansen, Nuage Vert,

13 Helen Evans and Heiko Hansen, Nuage Vert,

14 power-aware cord cord light pulsates & varies in intensity based on power draw [Gustafsson and Gyllenswärd, CHI2005]

15 HEATSINK thermistor senses water temperature, which feeds into a microcontroller that controls LEDs mounted around faucet Arroyo et al., Waterbot: exploring feedback and persuasive techniques at the sink, CHI 05

16 ello world intro arduino example

17 OPEN THE ARDUINO IDE

18 SELECT THE BOARD YOU ARE USING

19 SELECT THE COM PORT You will program your Arduino via the serial port over USB.

20 NOW, WE RE READY: LET S BLINK AN LED Arduinos typically have a single LED often called the L LED as this is how it s labeled on your board--that you can control from your sketches. The location of the L LED is circled below on the UNO and Leonardo. On the UNO and Leonardo, we can control this LED via D13 (digital pin 13). [source:

21 WRITING THE BLINK PROGRAM Goal: blink pin 13 (hooked up to the L LED on the board) once every 1 second.

22 WRITING THE BLINK PROGRAM Goal: blink pin 13 (hooked up to the L LED on the board) once every 1 second. The checkmark compiles and verifies the program

23 WRITING THE BLINK PROGRAM Goal: blink pin 13 (hooked up to the L LED on the board) once every 1 second. The checkmark compiles and verifies the program The right arrow sends the program to your Arduino

24 THE ENTIRE BLINK PROGRAM

25 SOME MODIFICATIONS I paramaterized the code a bit and added my own special prefix to track global variables.

26 [source:

27 ello world 2 blinky with external led

28 NOW, LET S BLINK OUR OWN LED

29 NOW, LET S BLINK OUR OWN LED To do this, we need to learn about two things: breadboards and LEDs.

30 readboards

31

32

33 BREADBOARDS: LOTS OF VARIETY [source: sparkfun.com]

34 BREADBOARDS: HOW THEY WORK [source:

35 BREADBOARDS: HOW THEY WORK wire1 wire2 wire3 wire4 [source:

36 BREADBOARDS: HOW THEY WORK wire1 wire2 wire10 wire9 wire8 wire7 wire6 wire5 wire13 wire12 wire11 wire18 wire17 wire16 wire15 wire14 wire20 wire19 wire23 wire22 wire21 wire28 wire27 wire26 wire25 wire24 wire30 wire29 wire34 wire33 wire32 wire31 wire3 wire4 [source:

37 [source: wire1 wire2 wire3 wire4 wire5 wire6 wire7 wire8 wire9 wire10 wire15 wire16 wire17 wire18 wire19 wire20 wire11 wire12 wire13 wire14 wire25 wire26 wire27 wire28 wire29 wire30 wire21 wire22 wire23 wire24 wire31 wire32 wire33 wire34 wire64 wire63 wire62 wire61 wire60 wire59 wire54 wire53 wire52 wire51 wire50 wire49 wire58 wire57 wire56 wire55 wire44 wire43 wire42 wire41 wire40 wire39 wire48 wire47 wire46 wire45 wire38 wire37 wire36 wire35 BREADBOARDS: HOW THEY WORK

38 BREADBOARDS: A LOOK INSIDE Breadboard now flipped over (you re looking at the back with the insulated backing peeled away) [source:

39 BREADBOARDS: A LOOK INSIDE A single strip of conductive metal from breadboard column [source:

40 BREADBOARDS: A QUICK TIP The power rails on either side are not connected, so if you want the same power source on both sides, you will need to connect the two sides with some jumper wires. Keep in mind that the markings are there just as a reference (you need not follow this convention if you have good reason not to). Two jumper wires used to connect the power rails on both sides. Always attach the + to + and the - to -. I also like to use black wire for - and red wire for +. [source:

41 DEFENSIVE BREADBOARDING Some Makers choose to only connect power on one side of the breadboard and ground on the other to reduce the chance of accidentally plugging a wire into the wrong socket and shorting out a circuit. Notice how the 5V and GND rails are only connected on opposite sides of the breadboard. This is to limit stupid mistakes! [source:

42 BREADBOARDS: LIKE LEGOS! Many breadboards have little nubbins and slots on the sides, and some even have them on the tops and bottoms. These allow you to connect multiple breadboards together to form the ultimate prototyping surface. [source: sparkfun.com]

43 BREADBOARDS VS. PERFBOARDS Sometimes novice Makers mistake breadboards for perfboards but they are completely different (though both allow you to hook up circuits in a semi-organized fashion).!= Breadboard Perfboard Breadboards are great for experimenting, and testing a circuit - but once you re happy with how it works, you ll probably want to transfer it to something that makes it a bit more permanent. In that case you can transfer your circuit to a perfboard. Perfboards require soldering. [source:

44 BREADBOARDS VS. PERFBOARDS Some perfboards have the same connections and hole spacings as a breadboard [source:

45 PERFBOARD USE [source:

46 NOW, LET S BLINK OUR OWN LED So, that s a quick intro to breadboards. Now we need to learn about LEDs.

47 Anode Cathode ight-emitting iodes (LEDs)

48 LEDS Anode LEDs have polarity: the long end is the positive lead Cathode [

49 LEDS Anode LEDs have polarity: the long end is the positive lead Cathode Helpful mnemonic: the long side is + and the negative side is -, so consider that the plus sign would be twice as long as the minus sign if its horizontal and vertical stroke were dissembled and placed end to end. [ Platt, Encyclopedia of Electronic Components]

50 LEDS Anode LEDs have polarity: the long end is the positive lead Cathode You cannot connect an LED directly to a battery or voltage source. You must include a resistor to limit the current flowing through the LED, otherwise the LED could burn out! [

51 LEDS Anode LEDs have polarity: the long end is the positive lead Cathode - + Long end of LED (anode) connected towards positive supply voltage Resistor Current limiting resistor to protect LED [

52 Current limiting resistor. An absolute must! + - Resistor

53 But how do we know what resistor value to select?

54 TRIAL AND ERROR! Makers know that their LEDs require current limiting resistors but they are often not so exact in selecting the theoretically optimal resistor. Instead, they pick a likely resistor value (e.g., 330Ω) and check the resulting brightness of their LEDs and iterate. See flow chart. Honestly, the easiest way to do this is via a variable resistor like a trimpot where you can adjust the resistance, find a good value, and then replace the trimpot with a permanent resistor of that value. This works fairly well in practice but it s important that you understand how to select an appropriate resistor as it involves key circuit skills like reading a datasheet and applying Ohm s law. [source:

55 - + Resistor SELECTING A CURRENT LIMITING RESISTOR Pseudo schematic Real schematic Though we ve been using the schematic representation on the left, the real electronics schematic representation is on the right. Both diagrams represent the same circuit. [source:

56 SELECTING A CURRENT LIMITING RESISTOR Using the circuit to the left, we need to know three values in order to determine the current limiting resistor value: 1. i : LED forward current in Amps (found in the LED datasheet) 2. Vf : LED forward voltage drop in Volts (found in the LED datasheet) 3. Vs : supply voltage Once you have obtained these three values, you can use this equation derived from Ohm s Law to find the value, in Ω, of the resistor: R = V s V f i [source:

57 Let s try an example

58

59

60 All we really need to know has been highlighted here by Sparkfun, but let s view the datasheet anyway as a learning exercise

61 LED DATASHEET

62 READING AN LED DATASHEET Forward Current: how much current your LED will be able to handle continuously. In this case, 20mA. Peak Forward Current: how much current the LED can sustain in short bursts. In this case, 30mA. Suggestion Using Current: not all data sheets provide this, but this company recommends operating the LED at 16-18mA for best performance Reverse Voltage: The maximum reverse voltage that the LED can sustain without damage (pay attention to this value if you often accidentally connect your LED anode to GND and cathode to VSS) Power Dissipation: The amount of power in milliwatts that the LED can use before taking damage [source:

63 READING AN LED DATASHEET Forward Voltage: The forward voltage is the voltage drop across the LED. You must reach this threshold to turn on the LED. In this case, 1.8V to 2.2V Wavelength: A precise way of explaining the color of the LED, in this case its nm LED Brightness: A measure of how bright the LED can get. The unit, millicandela (mcd), is standard for measuring the intensity of a light source. This LED has a luminous intensity of , which would make for a good indicator light (super bright LEDs can have 160, ,000mcd). Viewing Angle: Different style LEDs will incorporate different types of lenses, reflectors, or diffusers to concentrate light or spread it widely. [source:

64 EXAMPLE LED Using the circuit to the left, we need to know three values in order to determine the current limiting resistor value: 1. i : LED forward current in Amps. In this case, it s 20mA. 2. Vf : LED forward voltage drop in Volts (found in the LED datasheet). In this case, it s V, so let s say 2V. 3. Vs : supply voltage. In this case, let s say 5V (which is a common Arduino value) Once you have obtained these three values, you can use this equation derived from Ohm s Law to find the value, in Ω, of the resistor: R = V s V f i R = = 150 Ω [source:

65 EASY WAY TO TEST AN LED Just use a coin cell battery (e.g., a 3V) CR2025 or similar

66 SOME ADDITIONAL LED RESOURCES AddOhms #8 Current Limiting Resistors LED Current Limiting Resistors Electric Power

67 NOW, LET S BLINK OUR OWN LED So, that s a quick intro to breadboards and LEDs, let s get back to our example.

68 LET S HOOKUP OUR CIRCUIT The circuit is on the left and code is on the right

69 ello world 3 analogwrite and fading the LED

70 ARDUINO CODE: FADE THE LED ON/OFF

71 ello world 4 analogread to control the fade of the LED

72 ARDUINO CODE: FADE THE LED BASED ON ANALOGREAD Here, we will fade the LED based on the value of the analog input pin A0

73 HOW TO USE YOUR TRIMPOTS! You all have breadboard friendly trimpots, let s quickly learn a bit about them and how to use them in our circuits!

74 POTENTIOMETERS ARE EVERYWHERE! Used to adjust sensitivity, balance, input, output (especially in audio equipment)

75 HUGE VARIETY OF POTENTIOMETERS

76 SLIDE POTENTIOMETERS! [source:

77 SCHEMATIC SYMBOLS American Symbol European Symbol [source: Platt, Encyclopedia of Electronic Components: Volume 1, 2012]

78 THIS IS A BREADBOARD FRIENDLY TRIMPOT [source:

79 POTENTIOMETERS: HOW IT WORKS Inside the potentiometer is a single resistor and a wiper, which slides along the resisitive material. Externally, there are three pins: two pins connect to each end of the resistor while the third connects to the wiper.

80 POTENTIOMETERS: HOW IT WORKS Inside the potentiometer is a single resistor and a wiper, which slides along the resisitive material. Externally, there are three pins: two pins connect to each end of the resistor while the third connects to the wiper. B A W [source:

81 POTENTIOMETERS: HOW IT WORKS Inside the potentiometer is a single resistor and a wiper, which slides along the resisitive material. Externally, there are three pins: two pins connect to each end of the resistor while the third connects to the wiper. B A W If the resistive material in a potentiometer is of constant width and thickness, the electrical potential at the wiper will change in ratio with the rotation of the wiper and shaft (or with movement of a slider). [source:

82 POTENTIOMETERS: HOW IT WORKS B A W [source: Platt, Encyclopedia of Electronic Components: Volume 1, 2012]

83 FADE LED WITH A POTENTIOMETER Let s hookup the circuit first.

84 FADE LED WITH A POTENTIOMETER Let s hookup the circuit first. How would you write code to read the potentiometer value and then use this value to control the brightness of the LED?

85 FADE LED WITH A POTENTIOMETER The circuit is on the left and code is on the right

86 We can use Serial.println and the serial monitor to display our values Super useful for debugging!

87 ARDUINO SERIAL MONITOR Go to Tools -> Serial Monitor

88 ello world 5 Fading an LED and playing a tone

89 ARDUINO TONE() FUNCTION Generates a square wave of the specified frequency (and 50% duty cycle) on a pin. A duration can be specified, otherwise the wave continues until a call to notone(). The pin can be connected to a piezo buzzer or other speaker to play tones. Only one tone can be generated at a time. If a tone is already playing on a different pin, the call to tone() will have no effect. If the tone is playing on the same pin, the call will set its frequency. Use of the tone() function will interfere with PWM output on pins 3 and 11 (on boards other than the Mega). It is not possible to generate tones lower than 31Hz. For technical details, see Brett Hagman's notes. [source

90 FADE LED AND PLAY TONE The circuit is on the left and code is on the right

91 ello world 6 interacting with processing

92 Open Processing and copy/paste the code from here:

93

94 PROCESSING ARDUINO GRAPH

95 PROCESSING ARDUINO GRAPH The sketch should run right away with one exception, the highlighted part. Note: the code below is a slightly modified version of the Arduino Graph with my own variable names and code formatting You must change the index in Serial.list()[4] to whatever port your Arduino is plugged into. How do you know? See next slide.

96 SELECTING THE RIGHT SERIAL PORT You can open up the Arduino IDE and go to Tools -> Port and simply count (starting from 0) until you get to the COM port that is connected to your Arduino. index 0 index 1 So, my UNO is on COM6, which will be index 1 in the Serial.list() array

97 SELECTING THE RIGHT SERIAL PORT The sketch should run right away with one exception, the highlighted part. Note: the code below is a slightly modified version of the Arduino Graph with my own variable names and code formatting Changed to index 1

98 PROCESSING ARDUINO GRAPH From Serial Monitor to fanciful visualization. Note: you cannot have them both open at the same time! If you have the Arduino Serial Monitor open, you will not be able to read the serial port with your Processing program!

99 Can you modify the code so that the graph color is based on the analog value?

100 PROCESSING ARDUINO GRAPH Let s modify this graph so that the color is based on the input

101 SCROLLING, RESIZABLE ARDUINO GRAPH You will need to make your graph resizable for IA2

102 Can you draw and move a box across the screen based on the analog value?

103 MY SILLY DRAW RECTANGLE EXAMPLE

104 MY IA2 ARDUINO GRAPH DEMO Trimpot 10k; $0.95 Touch Membrane Potentiometer; $12.95 Photocell; $1.50 Flexiforce Pressure Sensor (1lb); $19.95

105 Playtime

106