Language - C: Difference between revisions

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==Write Code==
==Write Code==
{{WriteCode_Intro}}
You've followed the instructions above for your operating system and now have a working example. Next, we will show you how the example was created and how it works by getting into the code. When you are ready, head to our [[Phidget Programming Basics]] page. There you will find code examples writen in C/C++ and you will be writing your own code in no time!
 
=== Step One: Initialize and open ===
You will need to declare your Phidget object in your code. For example, we can declare a digital input object like this:
<syntaxhighlight lang=C>
PhidgetDigitalInputHandle ch;
</syntaxhighlight>
 
 
Next, the Phidget object needs to be initialized and opened:
<syntaxhighlight lang=C>
PhidgetDigitalInput_create(&ch);
Phidget_open((PhidgetHandle)ch);
</syntaxhighlight>
 
 
Although we are not including it on this page, you should handle the return values of all Phidget functions. Here is an example of the previous code with error handling:
<syntaxhighlight lang=C>
PhidgetReturnCode res;
const char* errorString;
 
res = PhidgetDigitalInput_create(&ch);
 
if(res != EPHIDGET_OK){
  Phidget_getErrorDescription ( returnValue, &errorString );
  printf("\n%s", errorString );
}
 
res = Phidget_open((PhidgetHandle)ch);
if(res != EPHIDGET_OK){
  Phidget_getErrorDescription ( returnValue, &errorString );
  printf("\n%s", errorString );
}
</syntaxhighlight>
 
=== Step Two: Wait for attachment of the Phidget ===
Simply calling open does not guarantee you can use the Phidget immediately. To use a Phidget, it must be plugged in (attached). We can handle this by using event driven programming and tracking the attach events. Alternatively, we can modify our code so we wait for an attachment:
 
<syntaxhighlight lang=C>
PhidgetDigitalInput_create(&ch);
Phidget_openWaitForAttachment((PhidgetHandle)ch, 5000);
</syntaxhighlight>
Waiting for attachment will block indefinitely until a connection is made, or until the timeout value is exceeded.
 
 
To use events to handle attachments, we have to modify our code slightly:
<syntaxhighlight lang=C>
PhidgetDigitalInput_create(&ch);
Phidget_setOnAttachHandler((PhidgetHandle)ch, OnAttachedHandler, NULL)
Phidget_open((PhidgetHandle)ch);
</syntaxhighlight>
 
Next, we have to declare the function that will be called when an attach event is fired - in this case the function ''OnAttachedHandler'' will be called:
<syntaxhighlight lang=C>
void CCONV OnAttachedHandler(PhidgetHandle ch, void *userPtr){
  printf("Phidget attached!");
}
</syntaxhighlight>
 
=== Step Three: Do things with the Phidget ===
We recommend the use of event driven programming when working with Phidgets. In a similar way to handling an attach event as described above, we can also add an event handler for a state change event:
 
<syntaxhighlight lang=C>
PhidgetDigitalInput_create(&ch);
Phidget_setOnAttachHandler((PhidgetHandle)ch,OnAttachedHandler, NULL);
PhidgetDigitalInput_setOnStateChangeHandler(ch, onStateChangeHandler, NULL);
Phidget_open((PhidgetHandle)ch);
</syntaxhighlight>
 
This code will connect a function and an event. In this case, the ''onStateChangeHandler'' function will be called when there has been a change to the devices input. Next, we need to create the ''onStateChangeHandler '' function:
<syntaxhighlight lang=C>
void CCONV onStateChangeHandler(PhidgetDigitalInputHandle ch, void *userPtr, int state){
  printf("State: %d", state);
}
</syntaxhighlight>
 
 
If events do not suit your needs, you can also poll the device directly for data using code like this:
<syntaxhighlight lang=C>
int state;
 
PhidgetDigitalInput_getState(ch, &state);
printf("State: %d", state);
</syntaxhighlight>
 
=== Step Four: Close and delete ===
At the end of your program, be sure to close and delete your device:
<syntaxhighlight lang=C>
Phidget_close((PhidgetHandle)ch);
PhidgetDigitalInput_delete(&ch);
</syntaxhighlight>


== Further Reading ==
== Further Reading ==

Revision as of 21:42, 9 June 2017

Quick Downloads

Documentation

Example Code

Libraries

Getting started with C/C++

Welcome to using Phidgets with C/C++! By using C/C++, you will have access to the complete Phidget22 API, including events. We also provide example code in C/C++ 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!

Visual Studio

Use our examples

One of the best ways to start programming with Phidgets is to use our example code as a guide. In order to run the examples, you will need to download and install Microsoft Visual Studio.


Now that you have Microsoft Visual Studio installed, select an example that will work with your Phidget:


Open the example project and start the example by pressing the Local Windows Debugger button:


C vs run.png


The application will open the Phidget, list basic information about the Phidget, and demonstrate the Phidget's functionality. Here is an example of an Accelerometer channel on a Spatial Phidget:


C vs output.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 C/C++ library. To begin:


Create a new Win32 Console application:

C vs newproject.PNG


After creating a project with the default settings, access the project's properties:

C vs properties.png


Next, navigate to Configuration Properties -> C/C++ -> General and add the following line to the additional include directories:

  • C:\Program Files\Phidgets\Phidget22


C vs additionalinclude.png


Navigate to Configuration Properties -> Linker -> Input and add the following line to the additional dependencies:

  • C:\Program Files\Phidgets\Phidget22\phidget22.lib


C vs additionadepend.png

Finally, include the Phidget library in your code: 

#include <phidget22.h>

Success! The project now has access to Phidgets. Next, view the write your own code section located below.

GCC

Cygwin/MinGW

Use our examples

One of the best ways to start programming with Phidgets is to use our example code as a guide. In order to run the examples, you will need to download and install either MinGW or Cygwin.


Now that you have either MinGW or Cygwin installed, select an example that will work with your Phidget:


If you are using Cygwin, navigate to the folder where the example is and open the command prompt. Enter the following command to compile the example: 

gcc example.c -o example -I"/cygdrive/c/Program Files/Phidgets/Phidget22" -L"/cygdrive/c/Program Files/Phidgets/Phidget22/x86" -lphidget22


If you are using MinGW, navigate to the folder where the example is and open the command prompt. Enter the following command to compile the example: 

gcc example.c -o example -I"C:/Program Files/Phidgets/Phidget22" -L"C:/Program Files/Phidgets/Phidget22/x86" -lphidget22

After running the commands above for either Cygwin or MinGW, an executable file called example.exe will be created. Enter the following command to run the example: 

example.exe


You should now have the example up and running. 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 exisiting project, you'll need to configure your development environment to properly link the Phidget C/C++ library.

To include the Phidget C/C++ library, add the following line to your code: 

#include <phidget22.h>

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.

Code::Blocks

Use our examples

One of the best ways to start programming with Phidgets is to use our example code as a guide. In order to run the examples, you will need to download and install Code::Blocks.


Now that you have Code::Blocks installed, select an example that will work with your Phidget:


Open the example in Code::Blocks (you do not need to create a new project) and navigate to Settings -> Compiler... as shown in the image below:

C codeblocks settings.png


From the Global compiler settings screen, navigate to Search directories -> Compiler and add the following directory:

  • C:\Program Files\Phidgets\Phidget22
C codeblocks compiler.PNG


Next, select Search directories -> Linker and add the following directory:

  • C:\Program Files\Phidgets\Phidget22\x86
C codeblocks linker.PNG


Finally, from the Global compiler settings screen, navigate to Linker settings and add the following line:

  • phidget22
C codeblocks libraries.PNG


You can now build and run the example:

C codeblocks 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 C/C++ library.


To include the Phidget C/C++ library, add the following line to your code: 

#include <phidget22.h>

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.

macOS

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

GCC

Use our examples

One of the best ways to start programming with Phidgets is to use our example code as a guide. You likely have gcc installed on your macOS machine already, but if not, you can easily get it by downloading Xcode.

Next, select an example that will work with your Phidget:


To compile the example program, enter the following command in the terminal: 

gcc example.c -o example -F /Library/Frameworks -framework Phidget22 -I /Library/Frameworks/Phidget22.framework/Headers

Finally, run the program by entering the following command in the terminal: 

./example


C mac gcc.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 exisiting project, you'll need to configure your development environment to properly link the Phidget C/C++ library.

To include the Phidget C/C++ library, simply add the following line to your code: 

#include <phidget22.h>

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.

Linux

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

GCC

Use our examples

One of the best ways to start programming with Phidgets is to use our example code as a guide. You likely have gcc installed on your Linux machine already, but if not, you can easily get it by entering the following command in the terminal: 

apt-get install gcc


Next, select an example that will work with your Phidget:


To compile the example, enter the following command in the terminal: 

gcc example.c -o example -lphidget22

After compiling, you can run the program by entering the following command in the terminal: 

./example


You should now have the example up and running. 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 exisiting project, you'll need to configure your development environment to properly link the Phidget C/C++ library.

To include the Phidget C/C++ library, simply add the following line to your code: 

#include <phidget22.h>

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.

Write Code

You've followed the instructions above for your operating system and now have a working example. Next, we will show you how the example was created and how it works by getting into the code. When you are ready, head to our Phidget Programming Basics page. There you will find code examples writen in C/C++ and you will be writing your own code in no time!

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.

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