QUARC Linux Verdex Target
| The QUARC Linux Verdex Target is a legacy target because the product lines using this target have been replaced with hardware based on the Gumstix DuoVero. Refer to the QUARC Linux DuoVero Target for details. |
One of the target types supported by QUARC is the Linux Verdex target. The Linux Verdex target currently supports OpenEmbedded (OE) Linux running on a gumstix™ Verdex board. This section provides a general description of the Linux Verdex target in addition to limitations and requirements for this target type. Please use the following list to refer to each topic:
Description
The QUARC Linux Verdex target currently supports the OpenEmbedded Linux Operating System (OS) running on a gumstix Verdex XL6P board. A gumstix Verdex board is a full-function miniature computer built and sold by Gumstix, Inc. (www.gumstix.com). The gumstix verdex XL6P motherboard has 32 MB of on-board flash memory and is run by a 600 MHz Marvell® PXA270 with XScale™ processor. Its full set of specifications is described at https://www.gumstix.com/support/hardware/verdex-pro/. The small form factor of the gumstix makes it very attractive to use for, for example, Unmanned Aerial Vehicle (UAV) applications.
The Linux Verdex target is a soft real-time system. The OE Linux operating system is not designed to guarantee that events are always processed within a particular timeframe, as in a hard real-time system. Thus, if an operation misses its deadline, it is considered "less" than correct but not an application or system failure. The system simply tolerates the missed deadline and performs the operation with delay. In real-time applications, this behaviour is undesirable since all operations must meet their deadlines. In particular, real-time control applications expect the sampling rate of the controller to be maintained, and no samples to be missed.
To minimize the delays in processing real-time events, the QUARC Linux Verdex target assigns the highest possible priority to a model's real-time code. The threads of the real-time code will preempt the threads of all other processes, including operating system processes performing important tasks, such as networking. Hence, a real-time process that executes for more than a brief interval may cause for example networking to be unresponsive.
Please keep in mind that using QUARC with a Linux Verdex target still requires a Windows host. Details on this requirement are given in the Requirements section of this page.
The gumstix refers to both a QUARC target type as well as a data acquisition card. For more information about the data acquisition cards supported by the QUARC Linux Verdex target, please refer to the QUARC Data Acquisition Card Support reference section in the QUARC documentation.
Limitations
There are a number of limitations imposed on the Linux Verdex target. The following is a list of these limitations:
Real-Time Performance
The Linux Verdex target is a soft real-time system. For real-time processes with critical
time constraints (e.g. advanced robotics), this target may not be suitable.
Sampling Rates
There is a limit on the fastest sampling time that can be set for a model using the QUARC system timebase. This limit is
1.3 milliseconds (using the modified OE Linux kernel, as recommended by Quanser).
You cannot have sampling times smaller than 1.3 milliseconds
when using the QUARC system timebase on a QUARC Linux Verdex target.
C++ Not Supported by All Compilers
The LLVM-based cross-compilers supplied with QUARC do not support C++. However,
the optional CodeSourcery Lite compiler do support C++.
Ad-hoc wireless network setup for Windows 8.1 and above
Due to limitations of Windows 8.1 and above, ad-hoc wireless network set up requies some manual steps.
Refer to Setting up Ad-hoc wireless network for Windows 8.1 and above
for detailed steps in setting up ad-hoc network. Note that the default SSID used for the Linux Verdex target is GSAH.
Requirements
As mentioned earlier on this page, running code on a gumstix target still requires a remote Windows host to be present. This is required since the code to be run on the Linux Verdex target first needs to be generated on a Windows system with MATLAB, Simulink and QUARC installed. Please note that even though QUARC must be installed on the Windows host, it is still necessary to have the QUARC runtime installed on the gumstix target, since the QUARC Target Manager must be present where the code is running.
Please note that if your only intended target is a gumstix, the QUARC Windows target is not required and you can select not to install that component when installing QUARC. However the QUARC Simulink Development Environment component is required to generate code from your Simulink models.
Unlike the old Linux Verdex target, quarc_linux_arm, the new Linux Verdex target supports cross-compilation tools to compile code for the gumstix Verdex board. Using a cross-compiler results in much faster compiles and downloads than in the previous generation.
Four different compilation options are available for the Linux Verdex target:
LLVM-GCC
The LLVM-GCC cross-compiler is supplied with QUARC. This compiler is used by default. The LLVM compiler is an open-source compiler that is extensible, so it is possible to modify the code generation or optimization phases of the compiler for static analysis, instrumentation and other capabilities and use those extensions with QUARC. Please refer to the LLVM Release License for licensing information.
LLVM-GCC based on CodeSourcery Lite
To use an LLVM-GCC cross-compiler based on CodeSourcery Lite, the appropriate CodeSourcery Lite compiler must be downloaded and installed. Detailed instructions on where to download CodeSourcery Lite and how to install it may be found at Installing CodeSourcery Lite.
The LLVM compiler is an open-source compiler that is extensible, so it is possible to modify the code generation or optimization phases of the compiler for static analysis, instrumentation and other capabilities and use those extensions with QUARC. Please refer to the LLVM Release License for licensing information.
CodeSourcery Lite
To use the CodeSourcery Lite compiler, the appropriate CodeSourcery Lite compiler must be first be downloaded and installed. Detailed instructions on where to find CodeSourcery Lite and how to install it with QUARC may be found at Installing CodeSourcery Lite.
Technical Support Package
Due to the high flexibility and customizability of a gumstix-based system together
with the specificity of the gumstix configuration required to optimally use and run QUARC,
only the Quanser products (e.g., ALTAV, Qbot) using a gumstix board are currently
directly supported by Quanser.
If required, please contact the Quanser Sales department for more details regarding running QUARC
on a gumstix board interfacing with your own application(s).
The following is a link to the
Quanser Contact Web Site.
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