Difference between revisions of "Language - Python"

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The project now has access to Phidgets. Next, view the [[#Write Code | write your own code]] section located below.
 
The project now has access to Phidgets. Next, view the [[#Write Code | write your own code]] section located below.
  
===Visual Studio + Python Tools for Visual Studio===
+
===Visual Studio===
 
+
 
====Use Our Examples====
 
====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.
  
1. Please ensure that the Phidget Python Module is installed onto your system.
+
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}}
  
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. A new project will need to be created. Generate a new Python project with a descriptive name such as PhidgetTest.
+
Next, create a new Python project:
 +
[[Image:Python_vs_newproject.PNG|link=|center]]
  
[[Image: VS New Project.png|link=|600px]]
 
  
4. Right click on the project in the Solution Explorer and select Add->Existing Item
+
Delete the Python file that was generated with the project:
 +
[[Image:Python_vs_delete.png|link=|center]]
  
[[Image: VS Add Exixting.png|link=|600px]]
 
  
5. Navigate to the folder with the examples and select the one you wish to open.
+
Add the example you just downloaded by right-clicking on the project and adding an existing item:
 +
[[Image:Python_vs_addexisting.png|link=|center]]
  
[[Image: VS Select Example.png|link=|600px]]
 
  
6. Right click the newly-loaded example file and select 'Set as Startup File'.
+
Select the example as the startup file:
 +
[[Image:Python_vs_startupproject.png|link=|center]]
  
[[Image: VS Set Startup file.png|link=]]
 
  
7. To run the program, under Debug select "Start Debugging"
+
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: VS Start Dubugging.png|link=|600px]]
+
[[Image:Python_version.PNG|link=|center]]
  
Here is an example output:
 
  
[[Image: VS Example Output.png|link=|600px]]
+
You can view/edit your Python environment under the ''Python Environments'' tab:
 +
[[Image:Python_vs_environment.png|link=|center]]  
  
====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.
+
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.
  
Then, in your code, you will need to include a reference to the Phidget Python library.
+
 
 +
To include the Phidget Python library, add the following line to your code:
  
 
<syntaxhighlight lang=python>
 
<syntaxhighlight lang=python>
Line 165: Line 170:
 
</syntaxhighlight>
 
</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:
+
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>
 
<syntaxhighlight lang=python>
Line 171: Line 176:
 
</syntaxhighlight>
 
</syntaxhighlight>
  
Please see the [examples] on how to add a reference to your particular Phidget.
+
You can now create your project as shown in the previous section.
 
+
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.
 
  
 +
The project now has access to Phidgets. Next, view the [[#Write Code | write your own code]] section located below.
  
 
===Eclipse + PyDev===
 
===Eclipse + PyDev===

Revision as of 23:06, 2 June 2017


Quick Downloads

Documentation

Example Code

Libraries

Getting Started with Python

Welcome to using Phidgets with Python! By using Python, you will have access to the complete Phidget22 API, 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:

Windows

If you haven't already, please visit the Windows page before you continue reading. There you will be instructed on how to properly set up your Windows machine so you can follow the guides below!

Install Phidget Python module

Before getting started with the guides below, ensure you have Python installed on your machine (both 2.7 and 3.6 are compatible with Phidgets). You will also need to download the Phidget Python module.

After unpacking the Phidget Python module, open the command prompt at folder location and enter the following command:

python setup.py install

This will build the module and install the Python module files into your site-packages directory.

Python install.png

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 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:


Open the command prompt at the location of the example and enter the following command:

python example.py


Python command run.png


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:

from Phidget22.PhidgetException import *
from Phidget22.Phidget import *

Then, you will also have to add a reference to your particular Phidget. For example, you would include the following line for a DigitalInput:

from Phidget22.Devices.DigitalInput import *

You can now compile the file as shown in the previous section.


The project now has access to Phidgets. Next, view the 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 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:


Right-click on the example and open it in IDLE:

Python idle open.png


To run the example, simply click on Run and select Run Module:

Python idle run.png


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:

from Phidget22.PhidgetException import *
from Phidget22.Phidget import *

Then, you will also have to add a reference to your particular Phidget. For example, you would include the following line for a DigitalInput:

from Phidget22.Devices.DigitalInput import *

You can now compile the file as shown in the previous section.


The project now has access to Phidgets. Next, view the 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 how to install the Phidget Python module section above. You will also need to download 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:


Next, create a new Python project:

Python vs newproject.PNG


Delete the Python file that was generated with the project:

Python vs delete.png


Add the example you just downloaded by right-clicking on the project and adding an existing item:

Python vs addexisting.png


Select the example as the startup file:

Python vs startupproject.png


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:

python -V
Python version.PNG


You can view/edit your Python environment under the Python Environments tab:

Python vs environment.png


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:

from Phidget22.PhidgetException import *
from Phidget22.Phidget import *

Then, you will also have to add a reference to your particular Phidget. For example, you would include the following line for a DigitalInput:

from Phidget22.Devices.DigitalInput import *

You can now create your project as shown in the previous section.


The project now has access to Phidgets. Next, view the 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 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 webpage, and then check the Phidget22 API 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.

PyDev Create Project.png

4. To import the example program into your project, right click the Project and select Import.

PyDev Import 1.png

5. On the next screen, select File System and proceed to the next screen.

PyDev Import 2.png

6. Browse to the directory where you extracted the examples into, and select the example you wish to open.

PyDev Import 3.png

7. The only thing left to do is to run the examples! Click on Run → Run.

Pydev Run.png

Once you have the Python examples running, we have a 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 section for instructions.

Then, in your code, you will need to include a reference to the Phidget Python library.

from Phidget22.PhidgetException import *
from Phidget22.Phidget import *

Then, you will also have to add a reference to your particular Phidget. For example, you would include the following line for a PhidgetDigitalInput:

from Phidget22.Devices.DigitalInput import *

Please see the 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 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:

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:

python setup.py install

This will build the module and install the built python module files into your site-packages directory.

Use Our Examples

First, download the 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 webpage, and then check the Phidget22 API 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.

python HelloWorld.py

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.

from Phidget22.PhidgetException import *
from Phidget22.Phidget import *

Then, you will also have to add a reference to your particular Phidget. For example, you would include the following line for a DigitalInput:

from Phidget22.Devices.DigitalInput import *

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 teaching section to help you follow the provided Python examples and which has resources such as the Phidget22 API 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:

python setup.py install

This will build the module and install the built python module files into your site-packages directory.

Use Our Examples

First, download the 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 webpage, and then check the Phidget22 API 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:

sudo python HelloWorld.py

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:

from Phidget22.PhidgetException import *
from Phidget22.Phidget import *

Then, you will also have to add a reference to your particular Phidget. For example, you would include the following line for a DigitalInput:

from Phidget22.Devices.DigitalInput import *

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 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 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 Phidget22 API.

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.

# 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)

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:

try:
  # Your code goes here
except PhidgetException as e:
  print (Phidget Exception %i: %s % (e.code, e.details))		
  exit(1)

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:

device.openWaitForAttachment(5000)
print ("%d attached!" % (device.getDeviceSerialNumber()))

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:

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....

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:

#Get the state from a digital input
digitalInputDevice.getState()

#Set the duty cycle for a digital output
digitalOutputDevice.setDutyCycle(0)

To catch data changes via events, you would use something like this:

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'

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!

device.close()

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.