Three Arduino Challenges to Connect the Logical World with the Physical One. ISTE Philadelphia

Transcription

1 Three Arduino Challenges to Connect the Logical World with the Physical One ISTE Philadelphia Rachel Brusky Christopher Fleischl Trevor Shaw Dwight-Englewood School, Englewood NJ

2 Table of Contents: I. Make It Shine Arduino Basics Challenge #1 -- Blink an LED on and Off Challenge #2 -- Chase pattern with four LEDs Challenge #3 -- Make it Fade! Apply what you know -- Illuminated Art Work II. Make It Move! Challenge #1 -- Connect the Hardware Challenge #2 -- Write the Program Apply what you know -- Create a moving sculpture III. Make It Go! How a motor works Task #1 -- Wire the Hardware Taks #2 -- Write the Sample Program Apply what you know -- Create a unique vehicle IV. Parts List

3 Make It Shine First, some Arduino Basics An Arduino is a tiny little computer. Unlike most computers, it doesn t have a screen, keyboard, hard drive, or even an operating system. But strictly speaking it is a computer. There are many different kinds of Arduinos. One of the most common types is the Arduino Uno. It is pictured below on the right. In today s workshop, we will be using the LightBlue Bean--pictured on the left. I like using these because they can be programmed from an ipad either by using the graphical programming app called Tickle or the native Arduino code from the Bean Loader app. This makes them a great tool to introduce kids to Arduino programming. Arduinos connect to things and control them. These things could be simple like an LED.

4 Or they can be complicated like all the sensors and motors of a robot. Arduinos connect to these things through pins. Different types of Arduinos have different numbers and configurations of pins. Pins come in two flavors: Analog and Digital I ll let you worry about analog pins another time. Today will be using the Digital ones. Challenge #1 -- Blink an LED on and Off Task #1 : Find the Digital pins on your Bean. See the pictures above for guidance. Digital Pins have two states: On and Off On means that there is electricity coming into or going out of the pin Off means that there is no electrical current detected on the pin HIGH / LOW is how we say On/Off in Arduino language Task #2: Plug the long leg of the LED into pin 2. Plug the short leg into the GND port on the Arduino.

5 Now that you know how to connect things to your Arduino, you might be wondering how to control the thing you connected. HINT: It s all about changing the state of a pin from HIGH to LOW or vice versa, and you do this by Programming. Arduino programs are called sketches. To write sketches for the bean, you can use one of two apps The Tickle App is a graphical programming environment that makes coding easy to learn. The Bean Loader app lets you write in native Arduino code and upload it to your bean wirelessly.

6 The instructions in today s workshop will assume that you are using Tickle to complete the challenges. Each time I refer to programming code, however, I will also include the native Arduino code right next to the Tickle code. If you want to use Bean Loader and write in native Arduino language, you may also want to refer to the second handout: Configuring Bean Loader to Program the Bean. Task #3: Get familiar with Tickle 3a. Launch Tickle and open the Nyan Whale Demo sketch. 3b. Play the game, and figure out how to switch to fullscreen. 3c. Change the background music to something a little less annoying. 3d. Instead of having it run forever, have the music and movement stop after 5 touches. Task # 4: Use Tickle to blink the LED

7 4a. Close the Nyan Whale sketch by clicking on the three horizontal lines next to the name of the sketch. 4b. Create a new sketch by clicking the +New Project button in the upper right corner and select Arduino Bean as the type of project. When the project opens, you will notice a few things: A sample sketch loads, which highlights some of the features of the bean. You now have access to additional command blocks that control the Bean. The Bean has been added as a character in your project. You can control it just like you controlled the Nayan Whale. And yes You guessed it you can add multiple characters (both physical and digital) to your project and have them interact with each other. (Not sure if you can add multiple beans. Why not give it a try?)

8 Tickle Bean Loader void setup() { pinmode(2,output); void loop() { digitalwrite(2,high); delay(1000); digitalwrite(2,low); delay(1000); When you run this program, if you plugged your LED correctly into Pin#2, you should see it flash on and off once per second. If not, check to make sure that your LED is plugged with the LONG leg into pin 2 and the short leg plugged into Gnd. Key things to notice: 1 is the same as HIGH or ON. When you write the value 1 to a digital pin, you turn it ON. 0 is the same as LOW or OFF. When you write the value 0 to a digital pin, you turn it OFF. Wait (in Tickle) or Delay (in Arduino) causes the program to pause for a specified amount of time. Tickle uses seconds. Arduino uses milliseconds. 4c. Adjust the value in the Wait command block to change the pattern of flashes. See what happens when you remove one or both of the wait commands. Challenge #2 -- Chase pattern with four LEDs If you re only plugging in a single LED, you can plug it directly into the board. To connect more than that, you will probably want to use a breadboard. In this project, we will light up a strand of LEDs in a chase pattern. Task #1: Setup the hardware 1a. Add 4 LEDs across the gutter of your breadboard. Be sure that the long leg of the LED is on right side of the gutter and the short leg on the left..

9 1b. Use jumper wires to connect the GND pin from the Bean to the neutral power bus on the left side of the breadboard. 1c. Use additional jumper wires to connect the left leg of each LED into the ground bus of the breadboard. 1d. Then connect the following pins from the Bean to the corresponding breadboard row for each LED: Pin 0 first LED Pin 1 second LED Pin 2 third LED Pin 3 fourth LED When You are finished, your breadboard should look like this

10 If the first LED in the series is connected correctly to GND and Pin 0, and you still have the Blink program from the previous exercise loaded on your bean, the first LED should be blinking on and off once per second. Key Question How can you modify the blink program below so that the LEDs connected to pins 1-3 blink in a series? Don t forget to set the pinmode for each of these additional pins in the setup block. Tickle Bean Loader void setup() { pinmode(2,output); void loop() { digitalwrite(2,high); delay(1000); digitalwrite(2,low); delay(1000); Task #2: Create a new sketch based on the Blink program that flashes the lights in a series. Play around with the delay settings and the order to make any fun pattern you like. Challenge #3 Make it Fade! The digitalwrite command has only two states: on and off. Pins 0-3 on the Bean support analog output as well as digital, allowing you to determine how ON something is. This allows you to change the brightness of an LED or the speed of a motor, etc.. The code below is a modification of the blink program. Turning an LED completely on or off, this will cycle the LED connected to pin 2 between half power (128) and full power (255). Tickle Bean Loader (Arduino)

11 void setup() { pinmode(2,output); void loop() { analogwrite(2,128); delay(1000); analogwrite(2,255); delay(1000); Variables are words or letters that stand for values (just like in math). Loops are blocks of code that repeat a set of instructions. The cool thing about variables in programming is that we can change their value during the execution of a program. Let s say we create a variable called x to hold the value we are going to use in our analogwrite() command. Instead of writing: analogwrite(0,128);

12 We could create the variable x and assign it the value of int x=128; Then we could write: analogwrite(0,x); Why would we want to do this? It seems like we are now using two lines of code to do what we were doing with one line in the previous example. We do it because now we can change the value of x in our program. If we reduce the value of x while analogwrite() executes over and over again, the LED will fade out. If we do the same while increasing the value of x, the LED will glow brighter. So how can we execute a command over and over again? We use a loop. Tickle Arduino void setup() { pinmode(2,output); void loop() { int x=0; while(x<=255) { analogwrite(2,x); x++; while(x>=0) { analogwrite(2,x); x--;

13 Task: Incorporate the code above into your program so that the lights fade in one at a time then fade out. Apply What You Know Now that you know how to turn lights on and off and make them fade, you can incorporate lights into lots of different decorations (paintings, greeting cards, holiday lights). Design a 2-dimensional picture that incorporates an array of LED lights, which you control from the Bean. Design a light up garment such as a tie, hat, shirt, belt, shoes, etc. Create a light up greeting card with an internal switch that is triggered when opened. Create a light up Solar System that emphasises the planets in a sequence.

14 Project #2 -- Make It Move! If you know how to use the analogwrite() command, you can control a servo motor. Servo motors are special types of motors that can move to precise positions. Any type of automated device that requires precise movement uses either a servo motor or a similar motor called a stepper. We change the position of a servo by changing the voltage going into one of it s three wires. Task #1: Wire up the hardware For this project, we are going to use 3 volts to power the motor. We can also power the Bean from the same 3v, so you can remove the coin cell from your bean. 1a. connect positive and negative battery wires to their respective bus location on the breadboard 1b. connect the Batt pin on the Bean to the positive power bus, and connect Gnd pin on the Bean to the negative bus. 1c. connect the brown wire of your servo to ground, connect the red wire to the positive bus, and connect the orange wire to pin 0 on the Bean. It should look like this:

15 When you start working with servos, the trickiest part is getting them calibrated to give you the angle that you want. You control the position of the servo arm by changing the value you use in your analogwrite() command. You need to play around with the value that you write to pin0 in order to get the servo to do what you want. We are using two different servo motors in our workshop today. One has a Black top. The other has a white top. I did a little experimenting and discovered the following PWM values for each: 0 degrees = degrees = 254 White Top 0 degrees = degrees = 250 Black Top So when you write your code, it should look something like this Tickle Bean Loader

16 void setup() { pinmode(0,output); void loop() { analogwrite(0,250); delay(7000); analogwrite(0,1); delay(7000); The values above assume you are working with one of the servos with the black top to it. If you are working with one of the white ones, you will need to adjust the values in the analogwrite commands. I m not a servo expert, and I have found them to be pretty temperamental. They get especially wonky when you are working with them below 4v as we are with the Bean, so if you need more precise and reliable servo control than what you can get with the Bean, it might be time to move up to a 5v Arduino board like the Uno. Apply What You Know Now that you know how to control the movement of a Servo motor, you can design and build an original sculpture with moving parts. Use any of the found or recycled materials we have in the class to create something that is innovative, unexpected, and fun to look at.

17 Project #3 -- Make It Go! If you have made it this far, you have learned how to connect wires and LEDs to the Bean. You have also learned how to turn those LEDs on and off using both the digitalwrite() and analogwrite() commands. You have also learned the following programming concepts in the Arduino language: Variable Loop If you can turn an LED on or off, you can turn anything on or off using your Arduino including a motor. BUT BE CAREFUL If you plug a motor directly into one of the digital ports on the Arduino, it will either not work or in some cases, it can draw too much current and fry the Bean. Let s avoid turning our workshop into a Mexican dinner and learn how to drive a motor the correct way. First, it s helpful to understand how a motor works A DC motor is made of a series of copper wire coils surrounded by a couple of magnets. when current passes through the coils, it creates a magnetic field that interacts with the magnets causing the shaft to spin. If you change the + and - direction of the current, the motor will spin in the opposite direction. The more current you supply, the faster the motor spins.

18 So We want to use our Arduino to selectively send current to our motor in one direction or another and at various power levels. Task #1: Wire up the hardware To control the current going to two motors, we need a chip called a motor driver. The motor driver is a special circuit called an H-Bridge. It is made up of a collection of transistors that allow us to change the direction and strength of current flow to the motor. Out of the package, the motor driver looks like this: Before we can use it on a breadboard, we need to solder some male headers onto it. Since the pins are labeled on the bottom of the board, we will mount this on our breadboard upside-down to make things easier to work with, so solder the headers such that the long parts are on the same side as the chip. Then mount it on your breadboard like this:

19 Next we will connect all of our components (Bean, Motor Driver, External Battery, Motors) using jumper wires. The steps below will walk you through that. First lets connect all of our ground wires. Items labeled ground should be constant throughout an electronic circuit. We will wire the driver ground pins together, connect them to ground on the Bean, and connect it all to the negative terminal of our external battery through the ground bus of the breadboard. Like this Next we will connect the parts that need positive voltage.

20 Now that we have connected power, we need to connect the wires that will control the motors. For each motor there are 3 wires-- two wires control direction (IN1 & IN2), and a third wire controls the speed (PWM). These pins are labeled A and B to distinguish the two motors. We will use Pins 0 and 1 to control speed for Motor A respectively. Connect Pin0 to the PWMA pin on the motor driver. Connect Pin1 to the PWMB pin on the motor driver. We will use Pins 2 and 3 to control direction for motor A. We will use Pins 4 and 5 to control direction for motor B. Connect Pin2 to AIN1 Connect Pin3 to AIN2 Connect Pin4 to BIN1 Connect Pin5 to BIN2

21 On the right side of the motor driver are the pins that actually drive the motors. For each motor there are two wires 01 and 02 for each motor A and B. Connect A01 and A02 to the terminals of one motor. Connect B01 and B02 to the terminals of the other.

22 Task #2: Create the Sample Program The sketch below will test to see that you have everything wired correctly. Now that we are using a lot more pins, I am going to name them using variables, so it will be easier to remember what they do.

23 Tickle Arduino //This sets up the variables and the mode of each pin int pwma=0; int pwmb=1; int fwda=2; int reva=3; int fwdb=4; int revb=5; void setup() { pinmode(pwma,output); pinmode(pwmb,output); pinmode(fwda,output); pinmode(reva,output); pinmode(fwdb,output); pinmode(revb,output); //this drives both motors forward void loop () { // drive both motors forward digitalwrite(fwda,high); digitalwrite(reva,low); digitalwrite(fwdb,high); digitalwrite(revb,low); delay(3000); //this drives both motors backward // drive both motors backward digitalwrite(fwda,low); digitalwrite(reva,high); digitalwrite(fwdb,low); digitalwrite(revb,high); delay(3000); // use a loop to increase the power to both motors from 0 to full int counter=0; while (counter<256) { analogwrite(pwma,counter); analogwrite(pwmb,counter); counter++; delay(250);

24 // Stop both motors digitalwrite(fwda,low); digitalwrite(reva,low); digitalwrite(fwdb,low); digitalwrite(revb,low); delay(3000); //Slowly increase power to both motors from 0 to 100% //Stop both motors

25 If things are wired correctly and this code was entered correctly, your motors should do the following: 1. Spin forward for 3 seconds 2. Spin backward for 3 seconds 3. Stop momentarily and then increase gradually in speed 4. Stop for 3 seconds So now you know how to control your motors. Your next task will be to construct a vehicle! Apply What You Know Using your knowledge of how to control DC motors, create a vehicle that can drive autonomously or be controlled from within the Tickle App. Be creative. Make a vehicle that doesn t look like a vehicle. Or a vehicle that reimagines household materials.

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27 Parts List All Projects Light Blue Bean (or microcontroller of your choice) Swiss Machine Pin Female headers. The bean comes without headers. Breadboard Jumper Wires AA Battery Holder (we used the 4 cell for make it go, but a 2 cell for the other two projects) Make it Shine 3mm LEDs various colors Wire (22 gauge solid) Make it Move Servo Motor (We used this part# from Sparkfun: ROB 09065) Make it Go Sparfun Motor Driver Dual H Bridge (ROB 09457) Male Headers to solder onto the motor driver Pair of DC Geared Hobby Motors (ROB 13258) Pair of Wheels (ROB 13259) Light Blue Bean can be purchased at Punch Through Design (www. punchthrough.com) Everything else is available from Sparkfun (