We recently released our new mainline-Kernel based Debian and Yocto BSPs for our i.mx6 based System on Modules. In this article we'll give you a short overview of the advantages of the new BSP era! Beside the recent Kernel Versions delivered, new userspace APIs have to be used to access peripherals.
Today we released a beta version of a new root file system for the SBC-SAMA5D36. The main changes are a new Kernel Version and the use of systemd as init system. The Kernel version is 4.9 and is a longterm maintained kernel (see this page for more information). Systemd has some advantages over sysv like parallel start of services (if possible), delaying of the start until a service or device is really needed, and it is compatible to the old sysv init scripts. Systemd also has some other advantages like builtin monitoring of running services and restart of them if they crash or stop working and also better dependency handling of services.
Use this beta release at your own risk. There are some known issues and mabye also some unknown ones. We will stabilize this release during the next weeks and bring out a stable release. Please find the release under following link:
In the past few months emtrion has broaden its knowledge base towards the open source virtualization platform Jailhouse . The eventual goal is to provide customers a virtualization solution that is real-time capable, lightweight, secure, certifiable and operable on emtrion hardware. The main advantage to customers will be the reduction of costs through the combination of multiple hardware units into one single unit that handles multiple tasks.
In general most of emtrion’s hardware comes with interfaces like Ethernet, RS232, CAN, GPIOs, I2C, SPI. In addition, the used CPU modules are supported by a powerful microprocessor.
Such preconditions are predestinated in controlling industrial systems. In many cases, programming in this environment is based on the widely-known standard IEC 61131-3.
If you consider these items, the question to ask is, are there any reason why you are not using emtrion's hardware as PLC. Not really. On the one hand it's dependent on the use case and its requirements such as real-time, certification etc. and the other hand on the effort needed to transform it to a PLC.
Transforming is an independent part of the use case and means to make an emtrion hardware a PLC. The transformation is limited by adding a piece of software, the so called RTS (runtime system) to the RFS (root filesystem).
The RTS we used, it is possible to make a PLC in less than one work day.
Following the proceeding steps are described.
Products for consumer market, industrial control systems and other embedded devices often require a touch screen display to offer both, visual feedback to the user, as well as an input method to interact with the system. In order to achieve a nicely designed and responsive user interface, developers can write their own graphical library providing widgets like drop-down menus, list-views, check-boxes or simple buttons. However, this can be a very tedious and error-prone task. It is best to use one of the available graphic libraries like Qt, Cairo, EFL or also emWin, not to forget to mention nCurses for console-style block-oriented graphics.
Now which library should one select, especially in terms of limited hardware resources on embedded systems but also with a look forward to the look&feel as well as the usability on a touch screen? Besides, hardware restrictions, like the used CPU and its computing power, available RAM-size, free space in ROM, availability of a GPU with 2D/3D hardware accelerated graphics and the used operating system, should be taken into consideration. emWin for example, runs on bare-metal systems either with or without a RTOS whereas Qt or EFL need at least a running Linux (but not said that it is impossible to run them on bare-metal). Other decision affecting parameters are the availability of the library as open- or closed-source, as well as the costs for non-commercial and commercial products. In the following article we will take a brief look at the Enlightenment Foundation Libraries (EFL) of a small Cortex-A5 based single board computer from emtrion running a Debian Jessie based Linux: the SBC-SAMA5D36 .
Linux is an operating system that is widely used in embedded systems such as consumer electronics, networking equipment, machine control, industrial, automation and so on and so forth. However, all systems do not have the same requirements in term of determinism and sometimes determinism, the ability to schedule the highest priority tasks in a consistent and predictable way, really matters. This is the case for Financial Services, Networking (QoS), Robots, Air Traffic Control Systems...
Compared to other real-time operating systems, Linux has the advantage to be open source with great hardware support. Yet it was not designed to be real-time. It was originally designed to be a time-sharing system where the goal is to give the best throughput from the hardware using all the resources at the maximum. This is the opposite requirement of the real-time constraints that needs determinism even at a low global throughput.
Throughout the years, different approaches have emerged to overcome this problem. The first approach is to modify the Linux Kernel itself in order to get the required latencies or the real-time APIs. This approach is covered by the project PREEMPT_RT led by the Linux kernel developers Ingo Molnar, Thomas Gleixner and Steven Rostedt. The second approach is to add a layer between the Hardware and the Linux kernel to handle the real-time requirements so that the Linux kernel behaviour can stay as it is. This approach has been taken into account by different project like RTLinux, RTAI and Xenomai. Since only the last one is maintained actively on ARM, we will only talk about it.