Language - C: Difference between revisions

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<metadesc>Communicate over USB with sensors, controllers and relays with Phidgets! Our C library supports Windows/MacOS/Linux using Visual Studio or GCC.</metadesc>
__NOTOC__
[[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.
 
General information of how to use Phidgets with C can be found in the '''Write Code''' section of each development environment page. This information is consistent across all pages.
 
==Choose Your Development Environment:==
 
{{Language_-_C_Dev_Environment_Table}}


== 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 16: Line 26:


{{AllQuickDownloads}}
{{AllQuickDownloads}}
== Getting Started with C ==
Welcome to using Phidgets with C! By using C, you will have access to the complete Phidget22 API, including events. Example code is also provided for each Phidget channel class.
If developing for Windows, keep reading; otherwise, select an operating system:
*[[#macOS | macOS]]
*[[#Linux | Linux]]
== Windows ==
===Install Phidget Drivers for Windows===
Before getting started with the guides below, ensure you have the following components installed on your machine:
# You will need the [[OS_-_Windows#Quick_Downloads|Phidgets Windows Drivers]]
===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 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]]
{{Edit_the_Examples}}
====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 begin:
Create a new Win32 Console application:
[[Image:C_vs_newproject.PNG|link=|center]]
Select an empty project and finish:
[[Image:C_vs_emptyproject.PNG|link=|center]]
If you are using a 64-bit machine, select x64, otherwise, keep x86:
[[Image:C_vs_configuration.png|link=|center]]
Next, add a new item to your source folder:
[[Image:C_vs_additem.png|link=|center]]
Give the source file a descriptive name and continue:
[[Image:C_vs_addsource.PNG|link=|center]]
Access the project's properties:
[[Image:C_vs_propertie.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, and any other header files:
<syntaxhighlight lang='C'>
#include <phidget22.h>
</syntaxhighlight>
[[Image:C_vs_finished.PNG|link=|center]]
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 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>
{{Edit_the_Examples}}
====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 include the Phidget 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 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]]
{{Edit_the_Examples}}
====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 include the Phidget 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==
===Install Phidget Drivers for macOS===
Before getting started with the guides below, ensure you have the following components installed on your machine:
# You will need the [[OS_-_macOS#Quick_Downloads|Phidgets macOS Drivers]]
===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 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]]
{{Edit_the_Examples}}
====Setting up a New 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 library.
To include the Phidget 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==
===Install Phidget Drivers for Linux===
Before getting started with the guides below, ensure you have the following components installed on your machine:
# You will need the [[OS_-_Linux#Quick_Downloads|Phidgets Linux Drivers]]
===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 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>
{{Edit_the_Examples}}
====Setting up a New 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 library.
To include the Phidget 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.
== Editing the Examples==
To get our example code to run in a custom application, simply remove the calls to ''AskForDeviceParameters'' and ''PrintEventDescriptions'', and hard-code the addressing parameters for your application.
If you are unsure what values to use for the addressing parameters, check the [[Finding The Addressing Information]] page.
For instance:
<syntaxhighlight lang=C>
AskForDeviceParameters(&channelInfo, (PhidgetHandle)ch);
prc = Phidget_setDeviceSerialNumber((PhidgetHandle)ch, channelInfo.deviceSerialNumber);
CheckError(prc, "Setting DeviceSerialNumber", &(PhidgetHandle)ch);
prc = Phidget_setHubPort((PhidgetHandle)ch, channelInfo.hubPort);
CheckError(prc, "Setting HubPort", &(PhidgetHandle)ch);
prc = Phidget_setIsHubPortDevice((PhidgetHandle)ch, channelInfo.isHubPortDevice);
CheckError(prc, "Setting IsHubPortDevice", &(PhidgetHandle)ch);
   
Phidget_setChannel((PhidgetHandle)ch, channelInfo.channel);
CheckError(prc, "Setting Channel", &(PhidgetHandle)ch);
if (channelInfo.netInfo.isRemote) {
    prc = Phidget_setIsRemote((PhidgetHandle)ch, channelInfo.netInfo.isRemote);
    CheckError(prc, "Setting IsRemote", &(PhidgetHandle)ch);
       
    if (channelInfo.netInfo.serverDiscovery) {
        prc = PhidgetNet_enableServerDiscovery(PHIDGETSERVER_DEVICEREMOTE);
        CheckEnableServerDiscoveryError(prc, &(PhidgetHandle)ch);
    } else {
        prc = PhidgetNet_addServer("Server", channelInfo.netInfo.hostname,
                    channelInfo.netInfo.port, channelInfo.netInfo.password, 0);
        CheckError(prc, "Adding Server", &(PhidgetHandle)ch);
    }
}
</syntaxhighlight>
Might become:
<syntaxhighlight lang=C>
prc = Phidget_setDeviceSerialNumber((PhidgetHandle)ch, 370114);
CheckError(prc, "Setting DeviceSerialNumber", &(PhidgetHandle)ch);
prc = Phidget_setHubPort((PhidgetHandle)ch, 2);
CheckError(prc, "Setting HubPort", &(PhidgetHandle)ch);
prc = Phidget_setIsHubPortDevice((PhidgetHandle)ch, 1);
CheckError(prc, "Setting IsHubPortDevice", &(PhidgetHandle)ch);
</syntaxhighlight>
Notice that you can leave out any parameter not relevant to your application for simplicity.
You can then manipulate the rest of the code as your application requires. A more in-depth description of programming with Phidgets follows in the [[#Write Code| Write Code]] section.
==Write Code==
{{WriteCode_Intro|C}}
=== Step One: Create and Address===
You will need to create your Phidget object in your code. For example, we can create a digital input object like this:
<syntaxhighlight lang=c>
PhidgetDigitalInputHandle ch;
PhidgetDigitalInput_create(&ch);
</syntaxhighlight>
Next, we can address which Phidget we want to connect to by setting parameters such as ''DeviceSerialNumber''.
<syntaxhighlight lang=C>
Phidget_setDeviceSerialNumber((PhidgetHandle)ch, 496911);
</syntaxhighlight>
Although we are not including it on this page, you should handle the return codes of all Phidget functions. Here is an example of the previous code with error handling:
<syntaxhighlight lang=C>
PhidgetReturnCode prc;
PhidgetDigitalInputHandle ch;
prc = PhidgetDigitalInput_create(&ch);
if (prc != EPHIDGET_OK) {
fprintf(stderr, "Runtime Error -> Creating DigitalInput: \n\t");
fprintf(stderr, "Code: 0x%x\n", error);
return 1;
}
prc = Phidget_setDeviceSerialNumber((PhidgetHandle)ch, 496911);
if (prc != EPHIDGET_OK) {
fprintf(stderr, "Runtime Error -> Setting DeviceSerialNumber: \n\t");
fprintf(stderr, "Code: 0x%x\n", error);
return 1;
}
</syntaxhighlight>
=== Step Two: Open and Wait for Attachment===
After we have specified which Phidget to connect to, we can open the Phidget object like this:
<syntaxhighlight lang=C>
Phidget_openWaitForAttachment((PhidgetHandle)ch, 5000);
</syntaxhighlight>
To use a Phidget, it must be plugged in (attached). We can handle this by calling ''openWaitForAttachment'', which will block indefinitely until a connection is made, or until the timeout value is exceeded. Simply calling ''open'' does not guarantee you can use the Phidget immediately.
Alternately, you could verify the device is attached by using event driven programming and tracking the attach events.
To use events to handle attachments, we have to modify our code slightly:
<syntaxhighlight lang=C>
PhidgetDigitalInputHandle ch;
PhidgetDigitalInput_create(&ch);
Phidget_setOnAttachHandler((PhidgetHandle)ch, onAttachHandler, null);
Phidget_openWaitForAttachment((PhidgetHandle)ch, 5000);
</syntaxhighlight>
Next, we have to declare the function that will be called when an attach event is fired - in this case the function ''onAttachHandler'' will be called:
<syntaxhighlight lang=C>
static void CCONV onAttachHandler(PhidgetHandle ph, void *ctx) {
    printf("Phidget attached!\n");
}
</syntaxhighlight>
We recommend using this attach handler to set any initialization parameters for the channel such as DataInterval and ChangeTrigger from within the AttachHandler, so the parameters are set as soon as the device becomes available.
=== 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>
PhidgetDigitalInputHandle ch;
PhidgetDigitalInput_create(&ch);
Phidget_setOnAttachHandler((PhidgetHandle)ch, onAttachHandler, null);
PhidgetDigitalInput_setOnStateChangeHandler(ch, onStateChangeHandler, null);
Phidget_openWaitForAttachment((PhidgetHandle)ch, 5000);
</syntaxhighlight>
This code will connect a function to an event. In this case, the ''onStateChangeHandler'' function will be called when there has been a change to the channel's input. Next, we need to create the ''onStateChangeHandler'' function:
<syntaxhighlight lang=C>
static void CCONV onStateChangeHandler(PhidgetDigitalInputHandle ph, void *ctx, int state) {
    printf("State: %d\n", state);
}
</syntaxhighlight>
If you are using multiple Phidgets in your program, check out our page on [[Using_Multiple_Phidgets]] for information on how to properly address them and use them in events.
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\n", state);
</syntaxhighlight>
'''Important Note:''' There will be a period of time between the attachment of a Phidget sensor and the availability of the first data from the device. Any attempts to get this data before it is ready will result in an error code, and a specific nonsensical result. See more information on this on our page for [[Unknown Values]].
====Enumerations====
Some Phidget devices have functions that deal with specific predefined values called enumerations. Enumerations commonly provide readable names to a set of numbered options.
Enumerations with Phidgets in C will take the form of '''ENUMERATION_NAME'''.
For example, specifying a SensorType to use the 1142 for a voltage input would look like:
<syntaxhighlight lang=C>
SENSOR_TYPE_1142
</syntaxhighlight>
and specifying a K-Type thermocouple for a temperature sensor would be:
<syntaxhighlight lang=C>
THERMOCOUPLE_TYPE_K
</syntaxhighlight>
The Phidget error code for timing out could be specified as:
<syntaxhighlight lang=C>
EPHIDGET_TIMEOUT
</syntaxhighlight>
You can find the Enumeration Type under the ''Enumerations'' section of the {{Phidget22API}} for your device, and the Enumeration Name in the drop-down list within.
=== 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 ==
[[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.

Revision as of 21:26, 20 June 2018


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.

General information of how to use Phidgets with C can be found in the Write Code section of each development environment page. This information is consistent across all pages.

Choose Your Development Environment:

C Development Environments
OS - Windows Windows

C VS WIN.png C VS WIN on.png

C GCC WIN.png C GCC WIN on.png

C CB WIN.png C CB WIN on.png

OS - macOS macOS

C GCC MAC.png C GCC MAC on.png

OS - Linux Linux

C GCC LNX.png C GCC LNX on.png

OS - Linux Phidget SBC Linux

C GCC SBC.png C GCC SBC on.png

Quick Downloads

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

Documentation

Example Code

Libraries

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