How to Connect to the Physical World
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You can connect your Scratch projects to the physical world using several different kinds of devices.
- MaKey MaKey
- LEGO WeDo Kit
- PicoBoard (also known as ScratchBoard)
- Kinect2Scratch, using Microsoft Kinect
- GoPiGo for Raspberry Pi
MaKey MaKey allows people to turn everyday objects into keys and use them with their computer.
- MaKey MaKey works by opening and closing circuits, using your body and other objects as conductors. It uses very little electricity, so it is safe, and you won't feel it.
- If you attach two alligator clips to the MaKey MaKey board and an apple and you, when you touch the apple you complete (close) the circuit and the computer recognizes this as a key is pressed. The MaKey MaKey uses standard "USB input device" drivers, so the computer thinks MaKey MaKey is a regular keyboard or mouse even though you have made your own unique key.
The default keys are the arrow keys, the space bar, and left click. They can be remapped using the website. Example use of MaKey MaKey:
- To make MaKey MaKey work with Scratch, plug in the USB to your computer and create a program like you normally would in Scratch. For example, when the right arrow key is pressed, the sprite moves 10 steps.
- Then connect one of the alligator clips to Earth at the bottom of the MaKey MaKey board and touch the metal at the other end of the alligator clip with your finger.
- Next connect another alligator clip to the apple and the right arrow on the MaKey MaKey board.
- When you touch the metal clip and apple at the same time, you complete a circuit and MaKey MaKey sends a signal to your computer saying a key is pressed. Every time you touch the apple your sprite will now move 10 steps
To purchase a MaKey MaKey, visit MaKey MaKey's website.
For information on how to set-up a MaKey MaKey, visit MaKey MaKey Set-Up.
For information on different materials to use with MaKey MaKey, visit MaKey MaKey Materials.
For information on troubleshooting MaKey MaKey, visit MaKey MaKey Troubleshooting.
Article on ideas of uses for MaKey MaKey, MaKey MaKey Article.
- Main article: LEGO WeDo Construction Set
The LEGO WeDo kit can be used to make motors and sensors interact with your Scratch project. It has a distance sensor, a tilt sensor, and a motor.
Example uses of the WeDo parts:
- Making a machine move when the distance sensor detects a certain distance.
- Wave your hand to change the size of a sprite when the distance sensor detects a certain distance.
- Using the motor to spin attached objects.
- Using the distance sensor' to control the speed of the motor.'
To find out more about LEGO WeDo parts and how you can use them in Scratch, LEGO Education WeDo Robotics Kit.
To purchase LEGO WeDo, visit LEGO Education Website.
- Main article: PicoBoard
The PicoBoard provides a way for you to make Scratch projects sense and respond to things going on in the world outside of your computer.
Examples of use with the PicoBoard:
- Use the sound sensor to make your sprite change how it looks whenever there is a loud sound.
- Use the light sensor to program a sprite to hop up or down whenever a shadow passes by.
- Use the slider and button to control a character in a video game.
- Use the USB cable and four sets of alligator clips that come with the PicoBoard to measure an electrical resistance in a circuit. The alligator clips can be used to build all kinds of custom sensors.
For more ideas on what to make visit the PicoBoard website.
To get started using the PicoBoard visit the PicoBoard Getting Started Guide.
To purchase a PicoBoard visit the SparkFun website.
If you own a ScratchBoard, a product similar to a PicoBoard that was sold through the Scratch website, the support information you'll find at the PicoBoard's website is applicable to your product as well.
If you own a ScratchBoard or PicoBoard and want to know about sensors that you can connect to it, look at the Sensor Types and Sources below.
Sensor Types and Sources
The following list shows different types of sensors that have been used in Scratch Sensor Board projects. (They are typically attached to alligator clip-heads plugged into sensor board jacks A, B, C, or D.) Visit the vendor site for pricing and ordering information.
Name; Description; Vendor Part Number
- Switch; Switch lever spdt 3A PCB; http://digikey.com SW773-ND.
- Temperature; Thermisor NTC 10K OHM 5%; http://digikey.com 317-1258-ND.
- Light; Photocell 5K-20K OHM 4.20 MM; http://digikey.com PDV-P9203-ND.
- Magnetic switch - 1; Switch Reed 10-15AT SPST .5A; http://digikey.com 420-1047-ND.
- Magnetic switch - 2; Switch Reed SPST .5A 12-23 A/T; http://digikey.com HE502-ND.
- Humidity; Consists of a metal electrode on a humidity sensitive membrane mounted on a ceramic substrate; http://rhopointcomponents.com SYH-1NC.
|Note:||When using resistive sensors with the XO microphone port, it appears that the interesting resistance range goes from around 2k to 5k. (Experimentally determined; your mileage may vary.)|
If you are looking for the files that explain how ScratchBoards/PicoBoards are made, they can be found at the Sensor Board Technical Information page.
Kinect2Scratch works by using the sensor recognition in Scratch and the Microsoft Kinect. The Microsoft Kinect works by recognizing certain bone movements in the human body, such as waving your arm, and Kinect2Scratch has created the software to have Scratch recognize this as well. Now you can use body movements to interact with the programs you create in Scratch!
To download the Kinect2Scratch software, visit Kinect2Scratch's Website.
For the set-up guide on how to install and use Kinect2Scratch, visit Kinect2Scratch's Set-Up Guide.
For ideas on what to do with Kinect2Scratch and sample projects, visit Kinect2Scratch's Examples.
GoPiGo for Raspberry Pi
GoPiGo is a robot that is controlled by an onboard Raspberry Pi to create an autonomous vehicle. The Raspberry Pi is a low-cost Linux-based computer that is very popular in the classroom. Once assembled, the GoPiGo can be controlled with Scratch 1.4, found on board the Raspberry Pi.
The easiest way to control GoPiGo is through Wifi and a portable computer running VNC viewer. That way, GoPiGo can be untethered. It's also possible to hook it up through an Ethernet cable, or even as a desktop setup with keyboard and monitor.
Details on how to set it up can be found at Getting Started with GoPiGo
- Make the GoPiGo go forward, backward, turn, and of course, stop.
- Blink your left turn signal, and then proceed with the turn.
- Take your GoPiGo outside and race each other. (wifi must be accessible)
To purchase a GoPiGo, visit GoPiGo Starter Kit Page
To see various projects that can be done with a GoPiGo, visit GoPiGo Projects.
- MaKey MaKey
- LEGO Education WeDo Robotics Kit
- Dexter Industries GoPiGo For Raspberry Pi
- Connecting to the Physical World (forum)