Welcome to emBLOG
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 NORM 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.
I may be a microcontroller guy myself, but there are times where you need the power of a microprocessor. Having an operating system handle the memory, peripherals and events just saves time, and some applications really do need the power a microprocessor provides.
Atmel’s SAMA5D3 family has some impressive devices. Based on ARM’s A5 architecture, they has an impressive amount of peripherals and I/O lines. To name just a few, the SAMA5D36 has 3 I2C ports, 6 SPI ports, 12 12-bit ADC channels, and something you don’t see every day, 7 UART ports. This is impressive enough, but to add to that, the SAMA5D3 also has up to 160 I/O pins, each with its own interrupt. The SAMA5 series is geared towards industrial environments, automotive devices, and with Atmel’s implementation of capacitive touch peripherals, it can be used on just about any application where a user must input data.
With all that power, it isn’t surprising that the German manufacturer emtrion used this processor for one of their development boards, the SBC-SAMA5D36. They not only went with the SAMA5D36 device for its power and reliability, but also for Atmel’s reactivity when it comes to support. Atmel has worked hard on Linux implementation, and so the Linux kernel has everything you need to access every part of the processor, but I’ll get into that later on.
Android has established itself as a dominant mobile operation system for consumers in recent years. It is indispensable in the field of applications such as smart phones, cameras, tablets, game consoles and much more. The Android-Software-Development- Kit (SDK) is extensively equipped and offers substantial possibilities for programming complex applications. Based on a complete Linux-kernel, Android is operated by a touch-based user interface. In fact, these are ideal conditions for the development of appealing and intuitive HMI applications in an industrial environment. However, especially in industry, there are further boundary conditions to be considered before Android can be used.