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Table of Contents > QUARC > User's Guide > QUARC Targets > Specific Targets

QUARC Linux RT ARMv7 Target

The Linux RT ARMv7 target currently supports Linux RT running on the National Instrument ELVIS III device. This section provides a general description of the Linux RT ARMv7 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 RT ARMv7 target currently supports NI Linux Real-Time Operating System (OS) running on an ARMv7 embedded board. The ARMv7 board has a 667 MHz dual core ARM Cortex-A9™ processor.

The Linux RT ARMv7 target is a hard real-time system. The NI Linux Real-Time Operating System is based on the PREEMPT_RT patch to the standard Linux kernel to faciliate its real-time performance. For more information, refer to the Introduction to NI Linux Real-Time white paper.

The QUARC Linux RT ARMv7 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 RT ARMv7 target still requires a Windows host. Details on this requirement are given in the Requirements section of this page.

For more information about the data acquisition cards supported by the QUARC Linux RT ARMv7 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 RT ARMv7 target. The following is a list of these limitations:

Real-Time Performance

Warning

The Linux RT ARMv7 target is an embedded system. The processor has good performance but is not comparable to a desktop computer. Hence, for real-time processes with significant computational requirements (e.g. advanced robotics), this target may not be suitable.

Sampling Rates

Warning

While very fast sampling periods may be configured using the system timer, there is a practical limit to how fast a model may run on the Linux RT ARMv7 target. Sampling periods faster than 2 kHz are not recommended.

Requirements

As mentioned earlier on this page, running code on a Linux RT ARMv7 target still requires a remote Windows host to be present. This is required since the code to be run on the Linux RT ARMv7 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 Linux RT ARMv7 target, since the QUARC Target Manager must be present where the code is running.

Please note that if your only intended target is a Linux RT ARMv7 target, 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.

 

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