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| == Operating System Support ==
| | #REDIRECT [[Phidget Programming Basics]] |
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| Phidgets can '''run directly''' on these operating systems:
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| * [[OS - Windows]]
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| * [[OS - Mac OSX]]
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| * [[OS - Linux]]
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| * [[OS - Windows CE]] ??
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| * [[OS - Android]] (3.1 and above)
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| Phidgets can be '''driven remotely''' by these operating systems:
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| * [[OS - Windows]]
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| * [[OS - Mac OSX]]
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| * [[OS - Linux]]
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| * [[OS - Windows CE]]
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| * [[OS - iOS]]
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| * [[OS - Android]]
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| == Language Support ==
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| Phidgets can be programmed either by an '''event-driven''' model, or by traditional '''linear code'''. All languages below support linear code. Some languages support our complete API, which includes support for event-driven design.
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| If you are flexible on what language you can use, we suggest choosing a language which supports event-driven code.
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| Phidgets have libraries to support [[#Event Driven Code|Event Driven Code]] in the following languages:
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| * [[Language - C/C++]]
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| * ...
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| Phidgets have libraries to support only [[#Linear Code|Linear Code]] in the following languages:
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| * [[Language - MATLAB]]
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| * ...
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| == General Phidget Programming ==
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| == Different Code Styles ==
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| User and device actions can be handled by either:
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| *Letting the program tell you when they happen and then doing something ('''event driven''' code)
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| *Polling for things to happen then doing something ('''linear''' code)
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| === Choosing A Code Style ===
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| The style of programming you choose (and hence the language you might prefer) would depend on what you want to do with the Phidget. The two sections, [[#Event Driven Code|Event Driven Code]] and [[#Linear Code|Linear Code]] below give benefits, drawbacks, and general examples of each style.
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| The styles can also mix. For example, you can take a defined set of steps at first such as turning on an LED or antenna (linear code) and then doing nothing until an output change event is fired (event code).
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| With languages that support both styles, you can mix and match. For languages that support only linear code (see the [[#Language Support|Language Support Categories]] above) you can only use the linear style.
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| Examples in pseudo-code are given below for each style type so you can see how your language choice can affect your code design.
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| === Event Driven Code ===
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| Event driven code allows for ''smooth handling of complex programs''. Event driven code '''is''' useful for:
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| *Handling multiple Phidgets
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| *Handling active plugging or unplugging of the Phidget (multiple attach and detach events)
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| *Working behind a GUI, as many GUIs are already event driven
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| *Capturing all sensor data - or input and output - device changes
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| Without event driven code, you will need to constantly poll the device to see if any state has changed. If you poll at a slower rate than your input or output changes, you will not capture all data.
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| Event driven code is usually '''not''' as useful or efficient for:
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| *Only one open and close event
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| *Using only one device
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| *Having the user (or program) '''put''' changes onto the device (in contrast to reading data '''from''' the device)
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| In addition, event driven code is relatively hard to design well. It may help to draw out a '''flowchart''', '''state machine''', or at least a '''pseudo-code outline''' of your system design and all events you wish to handle before writing code.
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| All [[#Language Support|Supported Languages]] that handle event driven code have examples of how to write such code on the specific language pages. Event driven examples follow this structure, and places to start changing this structure are noted:
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| <div style="background-color: #f3f3f3; border-color: #1c9edb; border-width:1px; border-style: dashed;">
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| <font size="3">
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| <source lang=text>
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| // --- Event Functions ---
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| Create any Language-Specific Functions (error handling, etc)
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| Create General Attach, Detach, and Error Handling Functions
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| On attach: Initialize hardware (antennas, etc)
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| On detach: Reset any state variables (attached boolean, etc)
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| Create Hardware-Specific Functions
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| // ****** Add your own handling code for these data change events ******
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| On data input change: Notify using basic output (screen message, turn on LED, etc)
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| // --- Main Code ---
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| Create Device Software Object
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| Attach Event Functions created above to Device
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| Open Device
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| // ****** Change the look and structure of this loop for your GUI ******
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| Loop waiting for events and user input:
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| If device attached:
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| Get and Print various device statuses on request via user input
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| Exit upon specific user input
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| Close Device
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| Delete Device
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| </source>
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| </font>
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| </div>
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| === Linear Code ===
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| Linear code is often more compact and straightforward compared to event driven code. But, linear code cannot easily handle the same level of complexity that event-driven code can. Linear code is useful for:
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| * Simple, single-device applications
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| * Non-GUI applications (GUIs usually are event driven)
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| * The user driving the device rather than listening to it
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| Linear code is relatively easy to design well. When the code example in the [[#Event Driven Code|Event Driven Code]] section above is translated into linear code, we lose the ability to handle multiple attach and detach events (plugging and unplugging of the Phidget). We also lose the ability to have all of the sensor data or event changes come to us, instead we have to ask for them. However, the code structure is much simpler:
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| <div style="background-color: #f3f3f3; border-color: #1c9edb; border-width:1px; border-style: dashed;">
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| <font size="3">
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| <source lang=text>
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| Create Device Software Object
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| Open Device
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| Wait for Device Attachment
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| Initialize any hardware (antennas, etc)
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| Loop waiting for requests from user input:
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| Get and Print various device statuses on request by input
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| Exit upon specific user input
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| Close Device
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| Delete Device
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| </source>
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| </font>
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| </div>
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| <br>
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| If you find that in linear code you have a highly complex <code>if</code> loop driving your program, you should consider switching to event driven code. This type of awkward if-loop might look like this:
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| <div style="background-color: #f3f3f3; border-color: #1c9edb; border-width:1px; border-style: dashed;">
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| <font size="3">
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| <source lang=c>
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| Create Device Software Object
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| Open Device
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| Loop Until Exit Requested {
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| if No Device Attached {
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| Wait For Attachment until Timeout
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| if Wait Timeout Reached {
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| break
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| } else {
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| Initialize Device
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| }
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| } else { // Device Is Attached
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| if Device Data Type 1 Changed {
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| Do Something
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| }
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| if Device Data Type 2 Changed {
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| Do Something Else
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| }
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| // ... More data change functions here
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| }
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| Collect User Input
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| }
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| Close Device
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| Delete Device
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| </source>
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| </font>
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| </div>
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| On the other hand, you can probably see that if your language does not give the option for events, you can use this structure to mimic what events would enable you to do.
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