Difference between revisions of "Language - Python"

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[[Category:Language]]
 
[[Category:Language]]
__TOC__
+
__NOTOC__
  
 +
We provide support for Python in all major operating systems. We also provide instructions on how to get your project started in a number of common development environments. Select your operating system and preferred development environment below, and follow the instructions to get your project running with Phidgets.
  
== Quick Downloads ==
+
If you do not know which development environment you want to use, or your development environment of choice is not listed, we recommend starting with command line or terminal as the simplest path to getting your code running.
  
=== Documentation ===
+
Once you have set up your development environment to run with Phidgets, we recommend you follow our guide on [[Phidget Programming Basics]]. The guide will showcase the fundamentals of programming with Phidgets, with examples in Python.
  
*{{Phidget22API}} (Select Python from drop-down menu)
+
==Choose Your Development Environment:==
  
=== Example Code ===
+
{{Language_-_Python_Dev_Environment_Table}}
  
*{{SampleCode|Python|Python Examples}}
+
== Quick Downloads ==
  
=== Libraries ===
+
If you already know what you're doing and just need the files, you can find them all below.
  
{{AllQuickDownloads}}
+
=== Python Module ===
 +
* [{{SERVER}}/downloads/phidget22/libraries/any/Phidget22Python.zip Phidget Python module]
  
== Getting Started with Python ==
+
=== Documentation ===
Welcome to using Phidgets with Python! By using Python, you will have access to the complete {{Phidget22API}}, including events. We also provide example code in Python for all Phidget devices.
+
  
If you are developing for Windows, keep reading. Otherwise, select your operating system to jump ahead:
+
*{{Phidget22API}} (select Python from the drop-down menu)
*[[#macOS | macOS]]
+
*[[#Linux | Linux]]
+
== Windows ==
+
{{Windows_Languages}}
+
  
===Install Phidget Python module===
+
=== Example Code ===
Before getting started with the guides below, ensure you have [https://www.python.org/downloads/ Python] installed on your machine (both 2.7 and 3.6 are compatible with Phidgets). You will also need to download the [{{SERVER}}/downloads/phidget22/libraries/any/Phidget22Python/zip Phidget Python module].
+
  
After unpacking the Phidget Python module, open the command prompt at folder location and enter the following command:
 
<syntaxhighlight lang=python>
 
python setup.py install
 
</syntaxhighlight>
 
 
This will build the module and install the Python module files into your site-packages directory.
 
 
[[File:Python_install.png|link=|center]]
 
 
===Command Line===
 
====Use Our Examples====
 
One of the best ways to start programming with Phidgets is to use our example code as a guide. Before we get started, make sure you have read [[#Install Phidget Python module | how to install the Phidget Python module]] section above.
 
 
 
Now that you have Python and the Phidget Python module installed, select an example that will work with your Phidget:
 
 
*{{SampleCode|Python|Python Examples}}
 
*{{SampleCode|Python|Python Examples}}
  
 
+
===Libraries===
Open the command prompt at the location of the example and enter the following command:
+
{{AllQuickDownloads}}
<syntaxhighlight lang=bash>
+
python example.py
+
</syntaxhighlight>
+
 
+
 
+
[[Image:Python_command_run.png|link=|center]]
+
 
+
 
+
You should now have the example up and running for your device. Play around with the device and experiment with some of the functionality. When you are ready, the next step is configuring your project and writing your own code!
+
 
+
====Configure your project====
+
When you are building a project from scratch, or adding Phidget functionality to an existing project, you'll need to configure your development environment to properly link the Phidget Java library.
+
 
+
 
+
To include the Phidget Python library, add the following line to your code:
+
 
+
<syntaxhighlight lang=python>
+
from Phidget22.PhidgetException import *
+
from Phidget22.Phidget import *
+
</syntaxhighlight>
+
 
+
Then, you will also have to add a reference to your particular Phidget. For example, you would include the following line for a DigitalInput:
+
 
+
<syntaxhighlight lang=python>
+
from Phidget22.Devices.DigitalInput import *
+
</syntaxhighlight>
+
 
+
You can now compile the file as shown in the previous section.
+
 
+
 
+
The project now has access to Phidgets. Next, view the [[#Write Code | write your own code]] section located below.
+
 
+
===IDLE===
+
====Use Our Examples====
+
One of the best ways to start programming with Phidgets is to use our example code as a guide. Before we get started, make sure you have read [[#Install Phidget Python module | how to install the Phidget Python module]] section above.
+
 
+
 
+
Now that you have Python and the Phidget Python module installed, select an example that will work with your Phidget:
+
*{{SampleCode|Python|Python Examples}}
+
 
+
 
+
Right-click on the example and open it in IDLE:
+
[[Image:Python_idle_open.png|link=|center]]
+
 
+
 
+
To run the example, simply click on ''Run'' and select ''Run Module'':
+
[[Image:Python_idle_run.png|link=|center]]
+
 
+
 
+
 
+
You should now have the example up and running for your device. Play around with the device and experiment with some of the functionality. When you are ready, the next step is configuring your project and writing your own code!
+
 
+
====Configure your project====
+
When you are building a project from scratch, or adding Phidget functionality to an existing project, you'll need to configure your development environment to properly link the Phidget Java library.
+
 
+
 
+
To include the Phidget Python library, add the following line to your code:
+
 
+
<syntaxhighlight lang=python>
+
from Phidget22.PhidgetException import *
+
from Phidget22.Phidget import *
+
</syntaxhighlight>
+
 
+
Then, you will also have to add a reference to your particular Phidget. For example, you would include the following line for a DigitalInput:
+
 
+
<syntaxhighlight lang=python>
+
from Phidget22.Devices.DigitalInput import *
+
</syntaxhighlight>
+
 
+
You can now compile the file as shown in the previous section.
+
 
+
 
+
The project now has access to Phidgets. Next, view the [[#Write Code | write your own code]] section located below.
+
 
+
===Visual Studio===
+
====Use Our Examples====
+
One of the best ways to start programming with Phidgets is to use our example code as a guide. Before we get started, make sure you have read [[#Install Phidget Python module | how to install the Phidget Python module]] section above. You will also need to download [https://www.visualstudio.com/ Microsoft Visual Studio] if you have not already.
+
 
+
Now that you have Python and the Phidget Python module installed, as well as Visual Studio, select an example that will work with your Phidget:
+
*{{SampleCode|Python|Python Examples}}
+
 
+
 
+
Next, create a new Python project:
+
[[Image:Python_vs_newproject.PNG|link=|center]]
+
 
+
 
+
Delete the Python file that was generated with the project:
+
[[Image:Python_vs_delete.png|link=|center]]
+
 
+
 
+
Add the example you just downloaded by right-clicking on the project and adding an existing item:
+
[[Image:Python_vs_addexisting.png|link=|center]]
+
 
+
 
+
Select the example as the startup file:
+
[[Image:Python_vs_startupproject.png|link=|center]]
+
 
+
 
+
Ensure that your Python environment is the same as the version you have installed. Enter the following command to view your Python version if you are unsure:
+
<syntaxhighlight lang=python>
+
python -V
+
</syntaxhighlight>
+
 
+
[[Image:Python_version.PNG|link=|center]]
+
 
+
 
+
You can view/edit your Python environment under the ''Python Environments'' tab:
+
[[Image:Python_vs_environment.png|link=|center]]
+
 
+
 
+
You should now have the example up and running for your device. Play around with the device and experiment with some of the functionality. When you are ready, the next step is configuring your project and writing your own code!
+
====Configure your project====
+
When you are building a project from scratch, or adding Phidget functionality to an existing project, you'll need to configure your development environment to properly link the Phidget Java library.
+
 
+
 
+
To include the Phidget Python library, add the following line to your code:
+
 
+
<syntaxhighlight lang=python>
+
from Phidget22.PhidgetException import *
+
from Phidget22.Phidget import *
+
</syntaxhighlight>
+
 
+
Then, you will also have to add a reference to your particular Phidget. For example, you would include the following line for a DigitalInput:
+
 
+
<syntaxhighlight lang=python>
+
from Phidget22.Devices.DigitalInput import *
+
</syntaxhighlight>
+
 
+
You can now create your project as shown in the previous section.
+
 
+
 
+
The project now has access to Phidgets. Next, view the [[#Write Code | write your own code]] section located below.
+
 
+
===Eclipse + PyDev===
+
 
+
====Use Our Examples====
+
1. Please ensure that the Phidget Python Module is installed onto your system.
+
 
+
2. Next, download the [[#Example_Code|examples]] and unpack them into a folder. While these examples were written in Python 3.4, they are also compatible with Python 2.6. It is probably best to start with the HelloWorld program, which will work with any Phidget. There is also an example file for your specific Phidget device. The source file will be named the same as the software object for your device. If you are not sure what the software object for your device is, find your Phidget on our [http://www.phidgets.com webpage], and then check the {{Phidget22API}} documentation for it. You will need this example source code to be imported into your project later on.
+
 
+
3. Next, a new project will need to be created. Generate a new PyDev project with a descriptive name such as PhidgetTest.
+
 
+
[[Image: PyDev Create Project.png|link=]]
+
 
+
4. To import the example program into your project, right click the Project and select Import.
+
 
+
[[Image: PyDev Import 1.png|link=]]
+
 
+
5. On the next screen, select File System and proceed to the next screen.
+
 
+
[[Image: PyDev Import 2.png|link=]]
+
 
+
6. Browse to the directory where you extracted the examples into, and select the example you wish to open.
+
 
+
[[Image: PyDev Import 3.png|link=|600px]]
+
 
+
7. The only thing left to do is to run the examples! Click on Run → Run.
+
 
+
[[Image: Pydev Run.png|600px|link=]]
+
 
+
Once you have the Python examples running, we have a [[#Edit the Examples|teaching section]] below to help you follow them.
+
 
+
====Write Your Own Code====
+
 
+
When you are building a project from scratch, or adding Phidget function calls to an existing project, you'll need to configure your environment to properly link the Phidget Python library. Please see the [[#Use Our Examples|Use Our Examples]] section for instructions.
+
 
+
Then, in your code, you will need to include a reference to the Phidget Python library.
+
 
+
<syntaxhighlight lang=python>
+
from Phidget22.PhidgetException import *
+
from Phidget22.Phidget import *
+
</syntaxhighlight>
+
 
+
Then, you will also have to add a reference to your particular Phidget. For example, you would include the following line for a PhidgetDigitalInput:
+
 
+
<syntaxhighlight lang=python>
+
from Phidget22.Devices.DigitalInput import *
+
</syntaxhighlight>
+
 
+
Please see the [[#Example_Code|examples]] on how to add a reference to your particular Phidget.
+
 
+
The project now has access to the Phidget function calls and you are ready to begin coding.
+
 
+
The same [[#Edit the Examples|teaching section]] which describes the examples also has further resources for programming your Phidget.
+
 
+
== OS X ==
+
 
+
The first step in using Python on Mac is to install the Phidget libraries. Compile and install them as explained on the [[OS - OS X]] page, which also describes the different Phidget files, their installed locations, and their roles....
+
 
+
The next step is to install the Phidget Python module. Download it here:
+
 
+
*[[Phidget Python Module]]
+
 
+
Then, unpack the module and enter the root of the newly unzipped directory. There will be a script in the base directory called setup.py. This is used the same way as most other distributed Python modules - from a command line type:
+
 
+
<syntaxhighlight lang=python>
+
python setup.py install
+
</syntaxhighlight>
+
 
+
This will build the module and install the built python module files into your site-packages directory.
+
 
+
===Use Our Examples===
+
 
+
First, download the examples:
+
 
+
*[[#Example_Code|Phidget Python Examples]]
+
 
+
Unpack them, and enter the root directory. You will find examples specific to each Phidget device, as well as a HelloWorld.py example. The HelloWorld.py code is probably the easiest example to run as it will work with any Phidget device. Or you can use the example specific to your Phidget. The source file will be named the same as the software object for your device. If you are not sure what the software object for your device is, find your Phidget on our [http://www.phidgets.com webpage], and then check the {{Phidget22API}} documentation for it.
+
 
+
The Phidget examples were written in Python 3.4 and this tutorial assumes its use. However, they should still be compatible with Python 2.6.
+
 
+
If needed, make those changes to the HelloWorld.py example or the one for your Phidget.
+
 
+
<syntaxhighlight lang=python>
+
python HelloWorld.py
+
</syntaxhighlight>
+
 
+
====Write Your Own Code====
+
 
+
When writing your code from scratch, you start it as you would any Python code, such as within a text editor like Emacs, Vi, Gedit, or Kate. In your .py source code file, you must include a reference to the Phidget module:
+
 
+
Then, in your code, you will need to reference to the Phidget Python library.
+
 
+
<syntaxhighlight lang=python>
+
from Phidget22.PhidgetException import *
+
from Phidget22.Phidget import *
+
</syntaxhighlight>
+
 
+
Then, you will also have to add a reference to your particular Phidget. For example, you would include the following line for a DigitalInput:
+
 
+
<syntaxhighlight lang=python>
+
from Phidget22.Devices.DigitalInput import *
+
</syntaxhighlight>
+
 
+
For other devices, it would be the software object you found when running the examples above. Then, you would run your Python code the same way as the examples.
+
 
+
To learn how to write your own code for your Phidget, and to learn more about our API, we have a [[#Edit the Examples|teaching section]] to help you follow the provided Python examples and which has resources such as the {{Phidget22API}} reference.
+
 
+
== Linux ==
+
 
+
Python has excellent support on Linux.
+
 
+
The first step in using Python on Linux is to install the Phidget libraries. These are the core Phidget libraries, written in C, which when compiled become part of the programming libraries available to your system. Download, compile, and install from the links and instructions on the main Linux page. That Linux page also describes the different Phidget files, their installed locations, and their roles.
+
 
+
The next step is to install the Phidget Python module. Download it here:
+
 
+
*Phidget Python Module
+
Then, unpack the module and enter the root of the newly unzipped directory. There will be a script in the base directory called setup.py. This is used the same way as most other distributed Python modules - from a command line type:
+
 
+
<syntaxhighlight lang=python>
+
python setup.py install
+
</syntaxhighlight>
+
 
+
This will build the module and install the built python module files into your site-packages directory.
+
 
+
===Use Our Examples===
+
 
+
First, download the examples:
+
 
+
*[[#Example_Code|Phidget Python Examples]]
+
 
+
Unpack them, and enter the root directory. You will find examples specific to each Phidget device, as well as a HelloWorld.py example. The HelloWorld.py code is probably the easiest example to run as it will work with any Phidget device. Or you can use the example specific to your Phidget. The source file will be named the same as the software object for your device. If you are not sure what the software object for your device is, find your Phidget on our [http://www.phidgets.com webpage], and then check the {{Phidget22API}} documentation for it.
+
 
+
The Phidget examples were written in Python 3.4 and this tutorial assumes its use. However, they should still be compatible with Python 2.6.
+
 
+
If needed, make those changes to the HelloWorld.py example or the one for your Phidget.
+
 
+
Then, if you have not set up your udev rules for USB access, you will need to run the Python example as root:
+
 
+
<syntaxhighlight lang="Python">
+
sudo python HelloWorld.py
+
</syntaxhighlight>
+
 
+
===Write Your Own Code===
+
 
+
When writing your code from scratch, you start it as you would any Python code on Linux, such as within a text editor like Emacs, Vi, Gedit, or Kate. In your .py source code file, you must include a reference to the Phidget module:
+
 
+
<syntaxhighlight lang=python>
+
from Phidget22.PhidgetException import *
+
from Phidget22.Phidget import *
+
</syntaxhighlight>
+
 
+
Then, you will also have to add a reference to your particular Phidget. For example, you would include the following line for a DigitalInput:
+
 
+
<syntaxhighlight lang=python>
+
from Phidget22.Devices.DigitalInput import *
+
</syntaxhighlight>
+
 
+
For other devices, it would be the software object you found when running the examples above. Then, you would run your Python code the same way as the examples.
+
 
+
To learn how to write your own code for your Phidget, and to learn more about our API, we have a [[#Edit the Examples|teaching section]] to help you follow the provided Python examples and which has resources such as the API reference.
+
 
+
== Edit the Examples ==
+
 
+
By following the instructions for your operating system and compiler above, you probably now have a working example and want to understand it better so you can change it to do what you want. This [[#Edit the Examples|teaching section]] has resources for you to learn from the examples and write your own.
+
Your main reference for writing Python code will be the {{Phidget22API}}.
+
 
+
=== Code Snippets ===
+
 
+
The following code snippets describe how to do various general tasks with Phidgets. You should be able to find places in the examples where these snippets exist, and modify them to suit your requirements.
+
 
+
==== Step One: Initialize and Open ====
+
 
+
Before using a Phidget, it must first be created and opened.
+
 
+
<syntaxhighlight lang=python>
+
# Create
+
try:
+
  device = DigitalInput()
+
except RuntimeError as e:
+
  print("Runtime Error: %s" % e.message)
+
+
# Open
+
try:
+
  device.open()
+
except PhidgetException as e:
+
  print (“Phidget Exception %i: %s” % (e.code, e.details))
+
  exit(1)
+
</syntaxhighlight>
+
 
+
The variable device is now a handle for the Phidget. This example is ''specific to the Digital Input'' because the call DigitalInput() is used. For another device, use the correspondingly named call in the Python API.
+
 
+
The handle '''device''' is then used for all the Python function calls using the Phidget for its device-specific functions - in this case, Digital Input specific functions. Every type of Phidget also inherits functionality from the Phidget base class.
+
 
+
Note that open() opens the software object, but not hardware. So, it is not a guarantee you can use the Phidget immediately.
+
 
+
Also note that you can catch exceptions thrown by the Phidget library as we did above when using the open() call. In other words, this should probably be present around most of your Phidget calls, especially when you are learning how to use the Phidget and debugging your code:
+
 
+
<syntaxhighlight lang=python>
+
try:
+
  # Your code goes here
+
except PhidgetException as e:
+
  print (“Phidget Exception %i: %s” % (e.code, e.details))
+
  exit(1)
+
</syntaxhighlight>
+
 
+
==== Step Two: Wait for Attachment (plugging in) of the Phidget ====
+
 
+
To use the Phidget, it must be plugged in (attached). We can handle this simply by calling openWaitForAttachment in place of the basic open. This function works for any Phidget. openWaitForAttachment will block until a connection is made to the Phidget, or the specified timeout is exceeded:
+
 
+
<syntaxhighlight lang=python>
+
device.openWaitForAttachment(5000)
+
print ("%d attached!" % (device.getDeviceSerialNumber()))
+
</syntaxhighlight>
+
 
+
Sometimes, it makes more sense to handle the attachment via an event. This would be in instances where the Phidget is being plugged and unplugged, and you want to handle these incidents. Or, when you want to use event-driven programming because you have a GUI-driven program. In these cases, an event-driven code snippet to handle the attachment might look something like this:
+
 
+
<syntaxhighlight lang=python>
+
def AttachHandler(e):
+
    attachedDevice = e
+
    serialNumber = attachedDevice.getSerialNum()
+
    deviceName = attachedDevice.getDeviceName()
+
    print("Hello to Device " + str(deviceName) + ", Serial Number: " + str(serialNumber))
+
+
# Insert code for -creating- device here....
+
+
try:
+
    device.setOnAttachHandler(AttachHandler)
+
except PhidgetException as e:
+
    # Insert code for handling any exceptions
+
    # A common exception will occur if you do not create the device properly above
+
+
# Insert code for -opening- device here....
+
</syntaxhighlight>
+
 
+
==== Step Three: Do Things with the Phidget ====
+
 
+
You can read data and interact with your Phidget both by polling it for its current state (or to set a state), or by catching events that trigger when the data changes.
+
 
+
For a Phidget Digital Input or Output, the polling method of getting the input state or setting an output state looks something like this:
+
 
+
<syntaxhighlight lang=python>
+
#Get the state from a digital input
+
digitalInputDevice.getState()
+
 
+
#Set the duty cycle for a digital output
+
digitalOutputDevice.setDutyCycle(0)
+
</syntaxhighlight>
+
 
+
To catch data changes via events, you would use something like this:
+
 
+
<syntaxhighlight lang=python>
+
def StateChangeHandler(e, state):
+
    print("State %f" % state)
+
    return 0
+
 
+
# Insert code to create an Digital Input called 'device'
+
+
# Hook our function above into the device object
+
    device.setOnStateChangeHandler(StateChangeHandler)
+
+
# Insert code to open 'device'
+
</syntaxhighlight>
+
 
+
==== Step Four: Close and Delete ====
+
 
+
At the end of your program, don’t forget to call close() to free any locks on the Phidget that the open() call put in place!
+
 
+
<syntaxhighlight lang=python>
+
device.close()
+
</syntaxhighlight>
+
 
+
== Further Reading ==
+
 
+
[[Phidget Programming Basics]] - Here you can find the basic concepts to help you get started with making your own programs that use Phidgets.
+
 
+
[[Data Interval/Change Trigger]] - Learn about these two properties that control how much data comes in from your sensors.
+
 
+
[[Using Multiple Phidgets]] - It can be difficult to figure out how to use more than one Phidget in your program. This page will guide you through the steps.
+
 
+
[[Polling vs. Events]] - Your program can gather data in either a polling-driven or event-driven manner. Learn the difference to determine which is best for your application.
+
 
+
[[Logging, Exceptions, and Errors]] - Learn about all the tools you can use to debug your program.
+
 
+
[[Phidget Network Server]] - Phidgets can be controlled and communicated with over your network- either wirelessly or over ethernet.
+

Latest revision as of 22:14, 28 February 2019


We provide support for Python in all major operating systems. We also provide instructions on how to get your project started in a number of common development environments. Select your operating system and preferred development environment below, and follow the instructions to get your project running with Phidgets.

If you do not know which development environment you want to use, or your development environment of choice is not listed, we recommend starting with command line or terminal as the simplest path to getting your code running.

Once you have set up your development environment to run with Phidgets, we recommend you follow our guide on Phidget Programming Basics. The guide will showcase the fundamentals of programming with Phidgets, with examples in Python.

Choose Your Development Environment:

Python Development Environments
OS - Windows Windows

PY PCH WIN.png PY PCH WIN on.png

PY CL WIN.png PY CL WIN on.png

PY LI WIN.png PY LI WIN on.png

PY VS WIN.png PY VS WIN on.png

PY IDLE WIN.png PY IDLE WIN on.png

OS - macOS macOS

PY CL MAC.png PY CL MAC on.png

OS - Linux Linux

PY CL LNX.png PY CL LNX on.png

OS - Linux Phidget SBC Linux

PY CL SBC.png PY CL SBC on.png

Quick Downloads

If you already know what you're doing and just need the files, you can find them all below.

Python Module

Documentation

Example Code

Libraries