| Design studies: CE and the single-board computer |
(Feb. 10, 2003)
Microsoft's rolling out a payload of articles discussing Windows CE apps. They're stressing software reliability. We're offering you exclusive first looks at some interesting technical contect. Building High Reliability Products Using Windows CE and Arcom's Single Board Computer Solutions, the second in our series, outlines several design projects utilizing CE on single-board computers made by Arcom. We hope you find it useful; let us know what you think in our talkback section. We'll be bringing you more material in the days and weeks ahead.
Building High Reliability Products Using Windows CE and Arcom's Single Board Computer Solutions
By Glen Middleton, Engineering Director of Arcom
Arcom designs and manufactures a wide range of standard and custom original equipment manufacturers (OEMs) single-board computers, based on the x86 personal computer (PC) architecture and Intel XScale, which are low power processors. These processors are combined with board support packages (BSPs) for the leading embedded operating systems including Windows CE, Windows XP Embedded, VxWorks, Embedded Linux, and QNX, to offer comprehensive ready-to-run development kits. Arcom also manufactures a wide range of PC/104 format input/output (I/O) modules and rugged industrial enclosures. Arcom's extensive hardware design, software integration, mechanical design, and manufacturing capabilities are available as a complete OEM Design Service. Arcom has sales, support, and design teams, in Kansas City, U.S. and Cambridge, U.K., and is a wholly owned subsidiary of Spectris, plc.
Marsh Encore-II
VideoJet
Videojet is one of the world’s pre-eminent industrial ink printing and scanner technology companies. Videojet builds equipment for high volume, continuous operation printing solutions. They used several Arcom single board computers based on AMD’s Elan processor and the National Semiconductor Geode, along with Windows CE 3.0.
One of the products is the Marsh Encore-II high resolution secondary packaging printer, a product targeted at printing information onto boxes travelling on conveyor systems. Videojet used Arcom’s SBC-GXm embedded PC to serve as a human-machine interface that would quickly process serial information from upstream equipment, such as check weighers, and interface this information to a custom, high-speed, digital signal processing (DSP) board linked to the inkjet print head.
The controller exchanges print data between the embedded PC and the print head driver using a dual port FIFO across the PC/104 bus interface. Blocks of data are streamed under interrupt control at a rate of 4 megabytes (MBs) per second. The equipment must reliably process 50 images per second and meet a minimum consistent interrupt latency of 100 us.
Chief Software Project Engineer, Adrian Moss, carried out a month of performance testing using Arcom’s Windows CE Development Kit to ensure that the system could achieve the real-time response and meet the requirements for interrupt and context switch times. Windows CE was also chosen for its comprehensive graphical user interface (GUI) library (output on a VGA TFT color display).
In terms of strategy, Moss felt that, "the Windows CE operating system offered the best technical solution for this task and a basis for future developments. Windows CE is a real-time operating system which gives me the right level of real time performance with the benefit of a very capable graphical user interface. This equipment must be totally reliable and this can only be achieved using reliable components."
TC2000 temperature calibrator
Scan-Sense
One of the first customers to use the Arcom 100MHz AMD SC400-based ELAN-104NC Windows CE Development Kit was Scan-Sense AS, in Norway. The development kit was supplied and supported by the system integrator Data Respons, Arcom’s distributor in Norway. Scan-Sense manufactures precision sensors and associated calibration instruments used by the process control industry, sensor manufactures, and research institutions. Scan-Sense recognised that their core competence was developing sensors and calibration techniques, not writing graphics libraries and I/O drivers. When they started development of the TC2000 temperature calibrator, they selected Windows CE. The choice was driven by the readily available GUI, serial communications, and support for Visual Basic.
Scan-Sense realised that this would offer the lowest entry cost and the fastest time to market for a product which needed good quality graphics support. By using a quarter VGA flat panel and matrix keypad, they were able to offer high-quality presentations of the calibration process within the lid of the calibrator. The availability of Arcom’s development kit and a pre-installed Windows CE image saved them several months of development and, most importantly, allowed them to start application development immediately.
Oivind Gundersen, product manager, from Scan-Sense commented, "Customers need complete confidence in this sort of specialist calibration equipment. Furthermore, the calibration instructions and recorded data must be presented in a clear, easy to use manner; the Windows CE environment offers the foundations to build quality instrumentation."
Marius Hauki, from system integrator Data Respons, added that "Buying a combined hardware/software solution from Arcom ensures we have a fully supported and known working environment, offering a fast time to market. Reliability is paramount for industrial control applications.”
Fluke’s 6100A Electrical Power Standard
Fluke
Another recent product launch has been Fluke’s 6100A Electrical Power Standard, a precision instrument for verifying and calibrating industrial power measuring devices. It is a phantom voltage and current source with the ability to introduce measured levels of harmonic distortion, and supply sag and flicker. This product uses Arcom’s 300MHz SBC-GX1 processor board with Windows CE 3.0 to control the entire instrument. By pursuing a well partitioned design, Fluke Senior Software Engineer, Kevin Harvey was able to offer the familiar Windows look and feel with the ability to control and process precision data.
To perform the front end signal processing, Fluke engineers used an array of eight dedicated digital signal processors linked to the SBC-GX1 through a high speed RS-485 link. Windows CE allowed them to regularly and consistently handle each digital signal processor (DSP) channel within a defined 100 milliseconds time slice.
"The two year development process with Windows CE presented considerably less problems than expected." said Harvey, "through the exhaustive product testing process, the operating system has behaved very well. As a market leading product, it is essential that we supply our customers with an easy to use interface with a wide selection of features."
The PC/104 expansion site on the SBC-GX1 is used to provide a GPIB IEEE488 instrument expansion interface for remote computer control and data acquisition.
Drill Line machine
Controlled Automation, Inc.
Finally, to show that Windows CE works just as well in the heavy end of industry, Controlled Automation Inc, a manufacturer of steel fabricating machinery and controls, used both Windows XP Embedded and Windows CE to create a real-time control system without the need for real-time extension software. The Drill Line machine includes three drill spindles, each having three independent axis of motion. Controlled Automation designed a PC/104 board fitted with four encoder/counter channels, 32 I/O channels, and a four-channel digital-to-analog converter (DA) to assist in performing the motion control and other general machine I/O.
Several Arcom SBC-GX1 single board computers running Windows CE 3.0 each implement the function of a dependent I/O controller, a hydraulic cylinder position controller, and a servo motor controller. The servo function implements a software digital filter and drives the analog output to each drill feed axis motor. Each instance of the servo and hydraulic controllers receives an interrupt request from an onboard timer 2000 times a second, to create the actual motion profile and monitor position. The profile command for speed, acceleration, and target position is issued as a distributed command from the host Windows XP Embedded-based system. The servo function controls the conveyor system and feed rate while drilling holes.
Buck Rogers, President of Controlled Automation, said "Since the servo function is implemented as a component object model (COM) component, the host Windows XP Embedded-based application can create as many instances as it needs. One board can run all three drills or, in our case the Windows XP Embedded creates one servo for each drill since each drill unit has its own controller. This maintains a highly distributed system with reduced wiring. To create a "soft" controller architecture, which will give us the maximum flexibility for new machine tool products, relies on a good level of determinism and reliable communication features. Real-time control is very crucial for the hydraulic and servo control and we demand excellent network performance for all the monitoring and task distribution.” Each Windows CE controller is also capable of communicating to Modbus/TCP-based devices. We use WAGO I/O devices in places that need a smaller controller."
The majority of Arcom’s customers load and run Windows CE and their application directly from the onboard embedded Intel StrataFlash devices. Arcom uses Datalight’s Flash media management software, FlashFX to implement the read/write Flash drive. The combination of Windows CE (both CE 3.0 and 4.x), FlashFX and Arcom’s hardware has proven to be reliable. Arcom is working closely with many more, leading companies developing Windows CE-based devices for a vast range of applications from GSM/GPRS mobile data monitoring for trucks to gaming machines, and in-store point of sale and promotions equipment. Today, customers have a wide choice of embedded operating offering a broad range of performance criteria and features. Using Windows CE in a carefully partitioned system offers excellent value for money, a familiar GUI, and a level of real-time responsiveness to capture a large slice of control and communications applications. Although reliability must be assessed on the basis of individual performance, feedback from Arcom’s diverse customer base testifies to a broad acceptance of Windows CE for high performance applications.
Copyright (c) 2003 Microsoft Corporation. All rights reserved. Reproduced by WindowsForDevices.com under license.
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