Language - C: Difference between revisions

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__NOTOC__
[[Category:Language]]
[[Category:Language]]
__TOC__
We provide support for the C language 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 GCC 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 C.
 
== Setup Guide ==
 
<div class="phd-deck-sequence">
{{PT3_C_CHOOSE}}{{PT3_C_WIN_VS}}{{PT3_C_WIN_VS_1}}{{PT3_C_WIN_VS_2}}{{PT3_C_WIN_CB}}
{{PT3_C_WIN_GCC}}{{PT3_C_MAC_GCC}}{{PT3_C_LNX_GCC}}{{PT3_C_SBC_GCC}}
</div>
 


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


=== Documentation ===
=== Documentation ===
Line 10: Line 25:
=== Example Code ===
=== Example Code ===


*{{SampleCode|C|C/C++ Examples}}
*{{SampleCode|C|C Examples}}


===Libraries===
===Libraries===


{{AllQuickDownloads}}
{{AllQuickDownloads}}
== 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:
*[[#macOS | macOS]]
*[[#Linux | Linux]]
== Windows ==
{{Windows_Languages}}
===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 [https://www.visualstudio.com/ Microsoft Visual Studio].
Now that you have Microsoft Visual Studio installed, select an example that will work with your Phidget:
*{{SampleCode|C|C/C++ Examples}}
Open the example project and start the example by pressing the ''Local Windows Debugger'' button:
[[Image: c_vs_run.png|link=|center]]
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:
[[Image: c_vs_output.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 C/C++ library. To begin:
Create a new Win32 Console application:
[[Image:C_vs_newproject.PNG|link=|center]]
After creating a project with the default settings, access the project's properties:
[[Image:C_vs_properties.png|link=|center]]
Next, navigate to Configuration Properties -> C/C++ -> General and add the following line to the additional include directories:
*C:\Program Files\Phidgets\Phidget22
[[Image:C_vs_additionalinclude.png|link=|center]]
Navigate to Configuration Properties -> Linker -> Input and add the following line to the additional dependencies:
*C:\Program Files\Phidgets\Phidget22\phidget22.lib
[[Image:C_vs_additionadepend.png|link=|center]]
Finally, include the Phidget library in your code:
<syntaxhighlight lang='C'>
#include <phidget22.h>
</syntaxhighlight>
Success! The project now has access to Phidgets. Next, view the [[#Write Code | 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 [http://www.mingw.org/ MinGW] or [https://www.cygwin.com/ Cygwin].
Now that you have either MinGW or Cygwin installed, select an example that will work with your Phidget:
*{{SampleCode|C|C/C++ Examples}}
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:
<syntaxhighlight lang='bash'>
gcc example.c -o example -I"/cygdrive/c/Program Files/Phidgets/Phidget22" -L"/cygdrive/c/Program Files/Phidgets/Phidget22/x86" -lphidget22
</syntaxhighlight>
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:
<syntaxhighlight lang='bash'>
gcc example.c -o example -I"C:/Program Files/Phidgets/Phidget22" -L"C:/Program Files/Phidgets/Phidget22/x86" -lphidget22
</syntaxhighlight>
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:
<syntaxhighlight lang='bash'>
example.exe
</syntaxhighlight>
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:
<syntaxhighlight lang='C'>
#include <phidget22.h>
</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.
===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 [http://www.codeblocks.org/downloads Code::Blocks].
Now that you have Code::Blocks installed, select an example that will work with your Phidget:
*{{SampleCode|C|C/C++ Examples}}
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:
[[Image:C_codeblocks_settings.png|link=|center]]
From the Global compiler settings screen, navigate to Search directories -> Compiler and add the following directory:
*C:\Program Files\Phidgets\Phidget22
[[Image:C_codeblocks_compiler.PNG|link=|center]]
Next, select Search directories -> Linker and add the following directory:
*C:\Program Files\Phidgets\Phidget22\x86
[[Image:C_codeblocks_linker.PNG|link=|center]]
Finally, from the Global compiler settings screen, navigate to Linker settings and add the following line:
*phidget22
[[Image:C_codeblocks_libraries.PNG|link=|center]]
You can now build and run the example:
[[Image:C_codeblocks_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 C/C++ library.
To include the Phidget C/C++ library, add the following line to your code:
<syntaxhighlight lang='C'>
#include <phidget22.h>
</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.
==macOS==
{{macOS_Languages}}
===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 [https://developer.apple.com/xcode/ Xcode].
Next, select an example that will work with your Phidget:
*{{SampleCode|C|C/C++ Examples}}
To compile the example program, enter the following command in the terminal:
<syntaxhighlight lang='bash'>
gcc example.c -o example -F /Library/Frameworks -framework Phidget22 -I /Library/Frameworks/Phidget22.framework/Headers
</syntaxhighlight>
Finally, run the program by entering the following command in the terminal:
<syntaxhighlight lang='bash'>
./example
</syntaxhighlight>
[[Image:c_mac_gcc.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 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:
<syntaxhighlight lang='C'>
#include <phidget22.h>
</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.
==Linux==
{{Linux_Languages}}
===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:
<syntaxhighlight lang='C'>
apt-get install gcc
</syntaxhighlight>
Next, select an example that will work with your Phidget:
*{{SampleCode|C|C/C++ Examples}}
To compile the example, enter the following command in the terminal:
<syntaxhighlight lang='bash'>
gcc example.c -o example -lphidget22
</syntaxhighlight>
After compiling, you can run the program by entering the following command in the terminal:
<syntaxhighlight lang='bash'>
./example
</syntaxhighlight>
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:
<syntaxhighlight lang='C'>
#include <phidget22.h>
</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.
==Write Code==
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 C/C++ 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=C>
//Create
PhidgetDigitalInputHandle device;
PhidgetDigitalInput_create(&device);
//Open
PhidgetReturnCode ret;
ret = Phidget_open((PhidgetHandle)device);
if(ret != EPHIDGET_OK)
{
  Phidget_getErrorDescription ( returnValue, &errorString );
  printf("\n%s", errorString );
}
</syntaxhighlight>
The variable "device" is now a handle for the Phidget. This example is ''specific to the Digital Input''. For another device, use the correspondingly named calls in the C API.
Note that Phidget_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 error codes returned by the Phidget library as we did above when using the Phidget_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=C>
PhidgetReturnCode ret;
const char* errorString;
ret = /*function call here*/;
if(ret != EPHIDGET_OK)
{
  Phidget_getErrorDescription ( returnValue, &errorString );
  printf("\n%s", errorString );
}
</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=C>
Phidget_openWaitForAttachment((PhidgetHandle)device, 5000);
</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=C>
void CCONV OnAttachedEventHandler(PhidgetHandle Device, void *userPtr)
{
  int serial;
  const char* deviceName;
  Phidget_getDeviceSerialNumber(Device, &serial);
  Phidget_getDeviceName(Device, &deviceName);
  printf("\nHello to Device %s, Serial Number: %d", deviceName, serial);
}
</syntaxhighlight>
And the code to set up the event handler within the code opening your device might look like:
<syntaxhighlight lang=C>
//Code for -creating- device here....
Phidget_setOnAttachHandler((PhidgetHandle)device,OnAttachedEventHandler, NULL)
//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=C>
//Get the state from a digital input
int state;
PhidgetDigitalInput_getState(digitalInputDevice, &state);
//Set the duty cycle for a digital output
PhidgetDigitalOutput_setDutyCycle(digitalOutputDevice, 0);
</syntaxhighlight>
To catch data changes via events, you would use something like this:
<syntaxhighlight lang=C>
void CCONV OnStateChangeHandler(PhidgetDigitalInputHandle digitalInput, void *userPtr, int state)
{
  printf("State: %d", state);
}
//...
//Within the function that opens the device
// Insert code to create an Digital Input called 'device'
// Hook our function above into the device object
  PhidgetDigitalInput_setOnStateChangeHandler(digitalInput, OnStateChangeHandler, NULL);
// Insert code to open 'device'
</syntaxhighlight>
==== Step Four: Close and delete ====
At the end of your program, don’t forget to close and delete the device to free any locks on the Phidget that opening the device put in place!
<syntaxhighlight lang=C>
Phidget_close((PhidgetHandle)device);
PhidgetDigitalInput_delete(&device);
</syntaxhighlight>
===C++ events===
If you want to use C++ style, object-oriented events you can do that as well. The following examples show you how to do this:
'''<span style="color:#FF0000">Figure out how to properly load these</span>'''
[[:File:Simple_22.cpp|Main]]
[[:File:Simple_22.h|Header]]
== 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 16:13, 15 March 2021

We provide support for the C language 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 GCC 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 C.

Setup Guide

C - Select Development Environment

Select your Development Environment:

Windows

MacOS

Linux

PhidgetSBC

Language - C

Windows with Visual Studio

Welcome to using Phidgets with C! By using C, you will have access to the complete Phidget22 API, including events.

Visual Studio is an IDE provided by Microsoft that can be used to develop code in a wide variety of programming languages, including C/C++.

Requirements

First, make sure you have the following installed:

● Phidgets Drivers for Windows (see Part 1 of this user guide)

● Microsoft Visual Studio

Using Phidgets in Your Programs

There are two ways you can use Phidgets in Visual Studio. You can either start from a sample project provided by our code sample generator, or you can start a new project from scratch.

Select your preferred method below for instructions:

Use our Code Sample

New Project

«
»

Visual Studio Code Sample

Finding Code Samples

To find the code sample to use for your Phidget, navigate to the Code Samples page and select your device from the drop-down menu.

Once you select your device, the code sample generator will give you a working code sample, and a selection of options to customize it to your needs.

Using the Code Samples

If it's unclear what any of the options do, click on the nearby '?' for more info.

Once you've made your selections, click the Visual Studio Project button under Downloads.

Using the Code Samples

Extract the files and open the .sln file.

Then start the example by pressing the Start button:

What's Next?

Now that you've set up Phidgets in your C programming environment, you should read our guide on Phidget Programming Basics to learn the fundamentals of programming with Phidgets.

In particular, you should ensure that you familiarize yourself with how error handling is done in C, because it's not automatically implemented like in other programming languages. Once you've added error handling to your code, you can use the Error Code List to anticipate and handle various errors.

Continue down below for advanced information and troubleshooting for your device.

«
»

Visual Studio New Project

Setting up a New Project

When using Phidgets in a Visual Studio project, you need to properly link the Phidget C library.

1. First, create a new Win32 Console Application:

Setting up a New Project

2. Select an empty project and Finish:

Setting up a New Project

3. If you are using a 64-bit machine, select x64, otherwise, select x86:

Setting up a New Project

4. Next, right click on the source folder and click New Item:

Setting up a New Project

5. Give the source file a name and click Add:

Setting up a New Project

6. Right click your project and access its properties:

Setting up a New Project

7. Go to Configuration Properties -> C/C++ -> General and add this to the additional include directories:

C:\Program Files\Phidgets\Phidget22

Setting up a New Project

8. Go to Configuration Properties -> Linker -> Input and add the appropriate line to additional dependencies:

C:\Program Files\Phidgets\Phidget22\phidget22.lib (for 64-bit systems)

C:\Program Files\Phidgets\Phidget22\x86\phidget22.lib (for 32-bit systems)

Setting up a New Project

9. Lastly, include the Phidget library at the beginning of your program:

#include < phidget22.h >

Success! The project now has access to Phidgets.

What's Next?

Now that you've set up Phidgets in your C programming environment, you should read our guide on Phidget Programming Basics to learn the fundamentals of programming with Phidgets.

In particular, you should ensure that you familiarize yourself with how error handling is done in C, because it's not automatically implemented like in other programming languages. Once you've added error handling to your code, you can use the Error Code List to anticipate and handle various errors.

Continue down below for advanced information and troubleshooting for your device.

«
»

Language - C

Windows with Code::Blocks

Welcome to using Phidgets with C! By using C, you will have access to the complete Phidget22 API, including events.

Code::Blocks is a free, open source cross-platform IDE that can be used for C and C++.

Requirements

First, make sure you have the following installed:

● Phidgets Drivers for Windows (see Part 1 of this user guide)

● Code::Blocks

Setting up a New 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 library.

To start, open Code::Blocks, and go to Settings -> Compiler as shown in the image below:

Setting up a New Project

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

C:\Program Files\Phidgets\Phidget22

Setting up a New Project

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

C:\Program Files\Phidgets\Phidget22\x86

Setting up a New Project

Next, go to Linker settings and add the following line:

phidget22

Setting up a New Project

Next, create a new Console Application project, as follows:

Setting up a New Project

Name your project, and finish creating the project.

Setting up a New Project

Now your project is created, and you can open the generated main.c to begin coding.

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

#include <phidget22.h>

Your project now has access to the Phidget libraries.

Finding Code Samples

To find the code sample to use for your Phidget, navigate to the Code Samples page and select your device from the drop-down menu.

Once you select your device, the code sample generator will give you a working code sample, and a selection of options to customize it to your needs.

Using the Code Samples

If it's unclear what any of the options do, click on the nearby '?' for more info.

Once you've made your selections, click the copy button and paste the code into your new project.

What's Next?

Now that you've set up Phidgets in your C programming environment, you should read our guide on Phidget Programming Basics to learn the fundamentals of programming with Phidgets.

In particular, you should ensure that you familiarize yourself with how error handling is done in C, because it's not automatically implemented like in other programming languages. Once you've added error handling to your code, you can use the Error Code List to anticipate and handle various errors.

Continue down below for advanced information and troubleshooting for your device.

«
»

Language - C

Windows with GCC

Welcome to using Phidgets with C! By using C, you will have access to the complete Phidget22 API, including events.

GCC is a compiler system for originally written for GNU, and is the standard compiler on unix-like operating systems. It is available on Windows by using tools like MinGW or Cygwin to allow compilation of C programs from the command line.

Requirements

First, make sure you have the following installed:

● Phidgets Drivers for Windows (see Part 1 of this user guide)

● One of the following:

- MinGW

- Cygwin

Finding Code Samples

To find the code sample to use for your Phidget, navigate to the Code Samples page and select your device from the drop-down menu.

Once you select your device, the code sample generator will give you a working code sample, and a selection of options to customize it to your needs.

Using the Code Samples

If it's unclear what any of the options do, click on the nearby '?' for more info.

Once you've made your selections, click the Download Example button under Downloads.

Compile and Run

Go to the folder where your code is and open the command prompt by typing 'cmd' in the address bar.

The specific command you will use depends on your compiler of choice:

Cygwin x86:

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

Cygwin x64:

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

MinGW:

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

Compile and Run

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 program:

example.exe

What's Next?

Now that you've set up Phidgets in your C programming environment, you should read our guide on Phidget Programming Basics to learn the fundamentals of programming with Phidgets.

In particular, you should ensure that you familiarize yourself with how error handling is done in C, because it's not automatically implemented like in other programming languages. Once you've added error handling to your code, you can use the Error Code List to anticipate and handle various errors.

Continue down below for advanced information and troubleshooting for your device.

«
»

Language - C

MacOS with GCC

Welcome to using Phidgets with C! By using C, you will have access to the complete Phidget22 API, including events.

GCC is a compiler system for originally written for GNU, and is the standard compiler on unix-like operating systems. It is available on Windows by using tools like MinGW or Cygwin to allow compilation of C programs from the command line.

Requirements

First, make sure you have the following installed:

● Phidgets Drivers for macOS (see Part 1 of this user guide)

● gcc


You likely have gcc installed on your macOS machine already, but if not, you can easily get it by downloading Xcode.

Finding Code Samples

To find the code sample to use for your Phidget, navigate to the Code Samples page and select your device from the drop-down menu.

Once you select your device, the code sample generator will give you a working code sample, and a selection of options to customize it to your needs.

Using the Code Samples

If it's unclear what any of the options do, click on the nearby '?' for more info.

Once you've made your selections, click the Download Example button under Downloads.

Compile and Run

To compile the program, enter the following command in the terminal, substituting "example" for the name of your C file:

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

Success! The project is now running with Phidgets.

What's Next?

Now that you've set up Phidgets in your C programming environment, you should read our guide on Phidget Programming Basics to learn the fundamentals of programming with Phidgets.

In particular, you should ensure that you familiarize yourself with how error handling is done in C, because it's not automatically implemented like in other programming languages. Once you've added error handling to your code, you can use the Error Code List to anticipate and handle various errors.

Continue down below for advanced information and troubleshooting for your device.

«
»

Language - C

Linux with GCC

Welcome to using Phidgets with C! By using C, you will have access to the complete Phidget22 API, including events.

GCC is a compiler system for originally written for GNU, and is the standard compiler on unix-like operating systems. It is available on Windows by using tools like MinGW or Cygwin to allow compilation of C programs from the command line.

Requirements

First, make sure you have the following installed:

● Phidgets Drivers for Linux (see Part 1 of this user guide)

● gcc


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

Finding Code Samples

To find the code sample to use for your Phidget, navigate to the Code Samples page and select your device from the drop-down menu.

Once you select your device, the code sample generator will give you a working code sample, and a selection of options to customize it to your needs.

Using the Code Samples

If it's unclear what any of the options do, click on the nearby '?' for more info.

Once you've made your selections, click the Download Example button under Downloads.

Compile and Run

To compile the program, enter the following command in the terminal, substituting "example" for the name of your C file:

gcc example.c -o example -lphidget22

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

./example

Success! The project is now running with Phidgets.

What's Next?

Now that you've set up Phidgets in your C programming environment, you should read our guide on Phidget Programming Basics to learn the fundamentals of programming with Phidgets.

In particular, you should ensure that you familiarize yourself with how error handling is done in C, because it's not automatically implemented like in other programming languages. Once you've added error handling to your code, you can use the Error Code List to anticipate and handle various errors.

Continue down below for advanced information and troubleshooting for your device.

«
»

Language - C

PhidgetSBC with GCC

Welcome to using Phidgets with C! By using C, you will have access to the complete Phidget22 API, including events.

GCC is a compiler system for originally written for GNU, and is the standard compiler on unix-like operating systems. It is available on Windows by using tools like MinGW or Cygwin to allow compilation of C programs from the command line.

Requirements

If you haven't already, check out the user guide in order to set up the following:

● Networking

● Administrator password


This guide will cover development using an external machine. For development using the SBC itself, go back and select GCC - Linux as your environment.

Introduction

To begin, this video will help you get started:

Developing With An External Computer

There are two main ways in which you can access your SBC from an external computer:

● SBC Web Interface

● Secure Shell (SSH)


Since the SBC User Guide covers the web interface in detail, this guide will cover SSH.

SSH

If you are unfamiliar with SSH, it is a simple yet powerful tool that allows you to log into a remote machine in order to execute commands. You can also transfer files using the associated SCP tool.

In order to use SSH, you need the following:

● The SBC's IP address (e.g. 192.168.3.195) or the link local address (e.g. phidgetsbc.local)

● The administrator password

● SSH enabled on the SBC

SSH

You can enable SSH on the SBC Web Interface as shown below:

SSH on Windows

To use SSH on Windows, we recommend PuTTY. Use the images below as a guide for configuring PuTTY (use the IP address or the link local address interchangeably):

SSH on Windows

After clicking open, simply login as root and provide the administrator password:

To transfer files between your SBC and Windows machine, we recommend either of these programs:

● WinSCP

● PuTTY PSCP

You will follow a similar process to access the SBC as described for SSH.

SSH on Linux and macOS

SSH is available on Linux and macOS by default. To run SSH, open the terminal and type:

ssh root@phidgetsbc.local

Or, something like this (you will need to know the IP address of your SBC):

ssh root@192.168.3.195

You will then be prompted for the password in order to gain access to the SBC:

SSH on Linux and macOS

To copy a file from the SBC to your development machine using SCP, open the terminal and type:

scp root@phidgetsbc.local:/path/to/source /path/to/destination

You can reverse this if you want to transfer a file from your development machine to your SBC:

scp /path/to/source root@phidgetsbc.local:/path/to/destination

Installing Packages For Development

Now that you are connected, you may want to start developing on the SBC.

Go to System->Packages, check Include full Debian Package Repository and click Install.

Finding Code Samples

To find the code sample to use for your Phidget, navigate to the Code Samples page and select your device from the drop-down menu.

Once you select your device, the code sample generator will give you a working code sample, and a selection of options to customize it to your needs.

Using the Code Samples

If it's unclear what any of the options do, click on the nearby '?' for more info.

Once you've made your selections, click the Download Example button under Downloads.

Setting up a New 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 library.

When developing on an external computer, you will write, compile, and test your programs on that machine. When you are ready, you will then upload your programs to the SBC to compile and run them.

Setting up a New Project

Once your code is written, follow these steps to get your program running on the SBC:

1. Using the SBC Web Interface, create a new project:

Setting up a New Project

2. Transfer all the project files from the development machine to the SBC, either using the SBC Web Interface or a tool like WinSCP.

The project directory will be:

/usr/userapps/ProjectName

Setting up a New Project

3. Use SSH to access the SBC terminal and go to the project folder:

cd /usr/userapps/ProjectName

Then compile the example by entering the following command in the terminal, replacing "example" with the name of your C file:

gcc example.c -o example -lphidget22

You can now run the program with the command:

./example

Success! The program is running on your SBC.

Running a Program Automatically

Click on the sections below for various automation options:

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Running a Program from the SBC Web Interface

To quickly test whether a program can be run automatically, you can try starting it from the SBC Web Interface.

1. To start the program, navigate to Projects->ProjectName->Startup Settings in the SBC Web Interface.

2. Select your program in the drop-down menu labeled Executable/Class Name.



3. Click the Start button on the SBC web interface.


4. You'll note that as it runs, there are two links below the Stop button which can be used to view the program output:

  • stdout: view the program output like you would in a terminal or command prompt
  • stderr: view the program error output
Run on Boot

Running on boot ensures that your program will never miss an event. As long as the SBC is running, your code will be running. This section assumes you have written and compiled your program on an external computer, and have uploaded it to the SBC Web Interface.


To have your program run on boot, navigate to Projects->ProjectName->Startup Settings in the SBC Web Interface. After selecting your project, copy the settings from the image below:



We will review some of the options that are shown in the image above:

  • Startup Order: lower numbers boot first. Booting later means more programs are available for use, booting earlier means other programs can use your program.
  • Run as a daemon: starts the program as a daemon. Unless you have explicitly written your program as a daemon, leave this checked, or else your SBC may hang on boot.
  • Executable/Class name: your main Java class or C file.
  • Arguments: any command line arguments the program needs.

After saving your changes, your program will run automatically whenever your SBC boots.

Run on a Schedule

Running your program on a schedule allows you to perform your task once a week, or once a minute without worrying about memory management issues or instability problems that may arise. It executes, and then gets cleaned up. To run your program on a schedule, we recommend using Cron. Cron can automatically schedule programs (known as jobs, or cron jobs). Cron simply reads a crontab file and runs whatever programs are listed, with whatever timing they are listed with. Cron runs continuously in the background, but the cron jobs only run as long as they naturally would, and then they exit.


Let's set up your first cron job. We will use nano to edit the crontab file, but feel free to use whatever editor you prefer.


First, set your editor to nano: 

export EDITOR=nano

Next, edit your crontab file: 

crontab -e

Finally, schedule your cron job: 

#cron job that will run at 5AM every week:
0 5 * * 1 /root/code/myprogram argument1


After entering your task, simply save and exit the file.

What's Next?

Now that you've set up Phidgets in your C programming environment, you should read our guide on Phidget Programming Basics to learn the fundamentals of programming with Phidgets.

In particular, you should ensure that you familiarize yourself with how error handling is done in C, because it's not automatically implemented like in other programming languages. Once you've added error handling to your code, you can use the Error Code List to anticipate and handle various errors.

Continue down below for advanced information and troubleshooting for your device.

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