Notice: This page contains information for the legacy Phidget21 Library. Phidget21 does not support VINT Phidgets, and will not support any new Phidgets. Phidget21 will be maintained until 2020. We recommend that new projects be developed against the Phidget22 Library.
Language - Flex AS3
Preamble about the language and its general strengths and weaknesses.
- 1 Assessment for use with Phidgets
- 2 Support
- 3 Restrictions
- 4 Development Environments and Compilers
- 5 Quick Downloads
- 6 Getting Started
- 7 Building your Project
- 8 Common Problems and Solutions/Workarounds
Assessment for use with Phidgets
Our honest opinion on how well this language is suited to controlling Phidgets. If it is a poor choice, suggest and link similar (better) languages.
Flex AS3 has a complete API and code samples for all Phidgets devices.
For a complete list of our supported languages and their support status, click here.
In this section, list any restrictions or limitations that this particular language may impose. For example, incompatibility with certain operating systems.
Development Environments and Compilers
Describe each major compiler and notable differences or important information. (eg. framework versions) If there are known issues/workarounds mention them and link to the corresponding issue at the bottom of the page.
Before you can run your program, you need to set up the proper environment and get the necessary files off the Phidgets website. Visit the drivers section at www.phidgets.com and get the latest:
You will need the Phidget Framework to use and to program with Phidgets. We also recommend that you download the following reference materials:
- API Manual
- API Reference
- Flex AS3 Sample Code
- You can find a high level discussion about programming with Phidgets in general on the General API page.
- The Device Functionality page explains the general operational information for your device.
You may want to have these pages open while working through these instructions.
The Phidget examples were written using Actionscript 3.0 under Adobe Flex Builder 3 and this tutorial assumes its use. Other development environments should work provided they support Actionscript 3.0, and each would be set up in a similar manner. First launch Flex and generate a new project with a descriptive name such as PhidgetTest. You will then need to add the Phidget Library to your project library path. This can be done under Project | Properties | Flex Build Path on the Library tab, by clicking the “Add SWC” button and selecting the Phidget21Library.swc from the Flex examples. As an alternative, you can copy the “com” folder that is located in the Flash AS3 examples into your project source directory and it should work as well.
Coding For Your Phidget
Before you can use the Phidget, you must import references from the library to the device in the main body of code. In MXML and Actionscript 3.0:
Afterwards, the Phidget object will need to be declared and then initialized. For example, a start function is set to execute on initialization, and then an instance of a PhidgetInterfaceKit is declared and then set inside with:
The object name for any type of Phidget is listed in the API manual. Every type of Phidget also inherits functionality from the Phidget base class.
Connecting to the Phidget
Next, the program needs to try and connect to the Phidget through an open call. Open will continuously try to connect to a Phidget, based on the parameters given, even trying to reconnect if it gets disconnected. This means that simply calling open does not guarantee you can use the Phidget immediately. We can handle this by using event driven programming and tracking the AttachEvents and DetachEvents, or checking the isAttached property.
The API manual lists all of the available modes that open provides. In Flash, the parameters can be used to open the first Phidget of a type it can find or based on its serial number. One important thing to remember is that when working with Phidgets, a local connection will reserve the device until closed. This means other programs that open the Phidget may end up preventing other instances from retrieving data. The one connection per device limit does not apply when exclusively using the Phidget WebService, and the Actionscript libraries by extension.
Event Driven Programming
We recommend the use of event driven programming when working with Phidgets. In Actionscript 3.0, we hook an event handler with the following code:
The onSensorChange method will get executed every time the PhidgetInterfaceKit reports a change on one of its analog inputs. The values from the report can be accessed from the PhidgetDataEvent object.
Some events such as Attach and Detach belong to the base Phidget object and thus are common to all types of Phidgets. Please refer to the API manual for a full list of events and their usage.
Working directly with the Phidget
Some values can be directly read and set on the Phidget and used as an alternative to event driven programming. Simply use the instance properties or call member functions such as getSensorValue(index: int) or setOutputState(index: int, val: Boolean) for PhidgetInterfaceKits.
Working with multiple Phidgets
Multiple Phidgets of the same type can easily be run inside the same program. In our case, it requires another PhidgetInterfaceKit instance to be defined and initialized. The new instance can then be set up, opened and used in the same process as the previous one. If the application needs to distinguish between the devices, open can be called with the serial number of a specific Phidget.
Flash Security Settings
During debugging or after publishing the project, you may encounter some difficulties with Flash network security settings either inside or outside of the development environment with Phidgets. Permissions for your project folder can be added through the settings manager at here, under “Always trust files in these locations” | “Edit locations...” | “Add location...”.
The design given in this document can also be followed for almost all Phidgets. For example, if you were using a PhidgetRFID instead of an PhidgetInterfacekit, you would declare a RFID object instead of a InterfaceKit object. The methods and events available would change but they can be accessed in a similar manner.
Building your Project
Describe the different ways a project could be built using this language.
Common Problems and Solutions/Workarounds
Here you can put various frequent problems and our recommended solutions.