Onboard Computers

Discussion in 'Wiki Archive' started by TerryKing, Mar 17, 2007.

  1. TerryKing
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    TerryKing On The Water SOON

    Discussion thread for Onboard Computers. If you would like to add a comment, click the Post Reply / New Reply button.
    Right now, I'd appreciate suggestions on the topics to be covered as seen in the CONTENTS section at the top. If there is something you'd like covered, or something that is confusing, please comment here! If you have knowledge of some area and would like to contribute please do so. Right now, it would be great to have:
    - An NMEA expert
    - Someone experienced with high-end fly-by-wire systems
    - Someone who knows Satellite data communications options
    - Probably other stuff we haven't thought about yet!
    If there are differences of opinion about something, let's thrash it out here on the discussion page!
     
    Last edited: Mar 18, 2007
  2. TerryKing
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    TerryKing On The Water SOON

    Portager and MarshMat, thanks for the great pointers! I am working on a Wiki item on Onboard Computers at http://www.boatdesign.net/wiki/Onboard_Computers
    May I use your information there?? I plan to add a section for details of board-level solutions including PC-104, Mini-ITX etc. I'd like to work out a typical configuration of those systems in a DIY case, with approximate pricing to be able to compare to the box-level offerings like TinyByte and LittlePC etc.

    The Wiki is supposed to be a collaborative effort and I'd appreciate your contributions there. Also, I'd appreciate it if you would review the Outline as shown in the Table Of Contents, and make suggestions about additions or changes. I hope we can pull some of the wisdom of the many discussions on BoatDesign.Net into easily-accessable summaries in the Wiki.

    There is a "Discussion" tab at the top of the Wiki pages that goes directly to the discussion thread here in the forums. Hope to see Y'all there!
     
  3. Portager
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    Portager Senior Member

    Feel free to use anything I post at you see fit.

    I took a look at the outline for the Wiki. Looks pretty good.

    For true boat controlls, I would look at PC/104 opto isolated input and relay output boards http://www.diamondsystems.com/products/ir104 . I can do amazing things with these.
     
  4. TerryKing
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    TerryKing On The Water SOON

    HomeWork...

    Portager, I would like to add a section at some point about electronic interfaces in general, for those who want to go to that level of customization. I have built systems with the old OPTO-22 and OPTO-MUX components, and although those are still used, I understand there are modern versions that are USB connected. I'm all for optical isolation in any more-complex system.

    I haven't used PC/104 components in a design (although one of my kids has.. I Must Be Old :eek: ). Some time could you put together a list of components that would make up an example PC/104 system, along with approximate prices, for the Wiki? And something about operating system options?

    It seems to me that there will always be a choice between 'consumer' single-board solutions like Mini-ATX and 'Industrial' multiboard solutions. What do you think?

    Marshmat, I'll look at the Vicor stuff more; I have used other DC-DC parts but not theirs. Have you seen any good 12 VDC output solutions that take (Unruly vehicle battery, starting transients, 16V high charge etc) as inputs and supply well-behaved 12VDC output for the more sensitive devices?

    Uh-Oh, I must have been hanging around schools too much lately... now I'm giving out HomeWork! :p

    Anyone else is invited to drop in...
     
  5. Portager
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    Portager Senior Member

    TerryKing

    Sorry I did not notice this request earlier, I've been very busy getting ready for and flying to a critical design review. Now that that is over I should have a little more free time (actually it would be more accurate to omit "more").

    I have used Industrial rack mounted PC's, Little PC's and PC/104 on marine applications. I think PC/104 is probably the best option for most personal boat applications because; they are easy to customize (no EE degree required), compact, rugged and they can be sealed in a COTS container for corrosion control and shock isolation. One thing that many people overlook is shock isolation. We have had many hard drive failures on marine systems with minimal or insufficient shock isolation.

    What would help with the component list is some idea of what the use of the system would be. For example would it run a Navigation system which would require an interface to a GPS, a hard drive and possible an external CD/DVD drive? Would it be used for communication and require cell phone modem or satellite link? Would the PC be used to monitor intrusion detection sensors for security while the owner is away, ...
     
  6. TerryKing
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    TerryKing On The Water SOON

    PC104 Systems

    Portager, Thanks for getting involved in this!

    Just like Hulls and Propulsion, many people will buy one made by someone else, and some will DIY. In both cases, more understanding of the internals and design considerations is A Good Thing. Appliance Operators won't show up at boatdesign.net.

    (Well, first there's the "What we want to / could do with onboard computers)...

    then, the choices, one of which is "Multi-purpose Onboard Computers"

    My thoughts about how to structure the Wiki relative to specific computer-based systems are, um (Moving Target: I just modified it a little):
    ---( copy from Wikii )------
    # 4 Multi-Purpose Onboard Computers and Interfaces

    * 4.1 Commercially Available "Marinized" Computers
    * 4.2 DIY Approaches to "Marinized" Computers
    o 4.2.1 Marine Environment
    * 4.3 Overview of Different Types of DIY Onboard Computer Systems
    o 4.3.1 Mini-ATX based Systems
    o 4.3.2 PC-104 based Systems
    * 4.4 Examples of Possible DIY Onboard Computer Systems
    o 4.4.1 Mini-ATX based Systems
    o 4.4.2 PC-104 based Systems
    ---( end )----

    Please comment on this or change it! This is a collaborative effort and I don't 'own' it...

    I'd like us to first try to do 4.3.1 (probably me) and 4.3.2 (probably you). This would be an introduction to the architecture, form factors and mechanical possibilities. Then the Processor options, Memory, Hard and Flash 'disk' storage, removable storage, network/serial interfaces, video/display options, human interface options, real-world I/O options, etc. Then Operating System options. Then a bit about the kind of onboard software that can be utilized and typical systems as used today. (What did I forget?) Maybe Power is a generic issue. No-- ATX is not used/useable for PC-104 is it? Hmmm..

    Later, I'd really like it if we (and others) could detail a specific onboard system they have built, as a working example. That would be the 4.4 section. Based on other stuff I've done, I think it gets confusing when you combine general information and architecture options with a specific system design.

    You've done actual onboard systems. We all will benefit from your onboard experiences and shock-mounting concepts. I've done many landlocked industrial systems, and an older land vehicle system. I will build an onboard system starting in May when I get back to the USA. Hopefully others will drop in here with their experiences.

    Speaking of that, I think we should start another thread about onboard computers, with references to the Wiki. What do you think??
     
  7. Portager
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    Portager Senior Member

    I agree we should probably start a new thread for on-board computers.

    Here is the beginning of my write-up on PC/104. As you can see there are many alternatives to PC/104, but PC/104 is the main option.

    There are two basic approaches to on-board computers. The most common, and cheapest in terns of initial cost, is to use a general purpose computer, generally a laptop, that is carried aboard and set-up on an available horizontal surface. These laptops slide around and maybe drop on the deck until someone decides to tie them down. Then they get shook and exposed to salt air until components start to come loose and/or contacts corrode and reliability becomes unacceptable. At this point, most people go out and purchase a new laptop, probably changing brands thinking that will help. The real problem is consumer grade computers are not designed for the marine operating environment. The best long term solution is to replace the general purpose PC with a rugged PC that is designed for harsh environments and also more expensive but lower cost in the long term. The second approach is an embedded computer that is mounted onboard and protected from the environment. This protection generally includes shock isolation, especially for high speed boats, and sealing it from the corrosive effects of the salt air. It may also include remotely locating the computer to reduce its exposure to temperature extremes, such as mounting it below deck instead of on the fly bridge. In general the embedded PC will be lower cost that a rugged laptop and easier to isolate from the environment.

    Embedded PC's are much more common than you realize. Everything from arcade games to vending machines have an embedded PC in them of some form or another. This production volume helps keep cost down. There are many commonly available form factors such as;
    Little Board - 5.75 x 8.0 in. single board computer,
    ISA "slot boards" - full-length, 13.8 x 4.8 in. and half-length, 7.1 x 4.8 in.,
    PC/104 - stacking 3.6 x 3.8 in. single board computers and expansion modules,
    PC/104-Plus - PCI bus added to PC/104,
    PCI-104 -PC/104+ without the ISA bus connector,
    EBX - PC/104-Plus added to Little Board,
    EPIC - shrunken EBX,
    EPIC Express - EPIC with PCI-express.

    However, no format is more widely supported or has more interchangeable expansion modules than the PC/104 and PC/104+ family. The EBX and Epic options have PC/104 expansion and more board area than a PC/104 SBC, so more features can be accommodated on the main board (fewer expansion modules required) and they support PC/104(+) expansion modules. However, the larger main board of EBX and EPIC means the enclosure will have a lower volumetric efficiency. In general little board is used for embedded applications that do not need expansion modules. EBX and EPIC are used mainly when one or two expansion modules are required. If more than two expansion modules are required, then PC/104 is probably the best option. BTW: all generalizations are false including this one.

    PC/104

    The PC/104 standard was developed by Ampro and the specification was initially released in 1992 http://www.pc104.org/technology/PDF/PC104 Spec v2_5.pdf to provide a compact, high reliability form factor for embedded computer systems see also http://www.pc104.org/technology/reg_info.html. It features 90 by 96 mm (3.550 by 3.775 inches) boards with 104 (64 pins on P1, plus 40 pins on P2) stacking through connectors. The stack through connectors allow the boards to be stacked in parallel layers instead of at right angles, using 15 mm (.6")spacers to form a very small and compact package.

    PC/104+

    The PC/104+ specification was initially released in February 1997 http://www.pc104.org/technology/PDF/PC104-Plus v2.0.pdf and it adds a stack though connector for the higher speed PCI bus http://www.pc104.org/technology/plus_info.html. The PC/104+ cards are fully compatible with PC/104 cards so PC/104+ and PC/104 cards can be combined in a single stack provided the PC/104+ cards are all at one end of the stack. However, you can only use 5 PC/104+ cards in a stack, the host plus 4 PC/104+ expansion modules.
     
  8. TerryKing
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    TerryKing On The Water SOON

    Pc104

    Portager, This is looking good! Let me know when/if you want me to move/format it into the Wiki.. You can keep editing it here for a while if you want..

    One question: The term for a rugged PC mounted in a protected place onboard. The term "Embedded" is widely used for microcomputer-based embedded applications these days, and Embedded Systems is a discipline almost of it's own... It might be confused here by some people. Maybe some term including.. mmm.. "protected mount rugged PC" or something??? What do you think??

    I'll dig some more into the PC-104 specs...
     
  9. Portager
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    Portager Senior Member

    According to Wikipedia http://en.wikipedia.org/wiki/Embedded_system

    "Embedded system
    From Wikipedia, the free encyclopedia

    An embedded system is a special-purpose system in which the computer is completely encapsulated by or dedicated to the device or system it controls. Unlike a general-purpose computer, such as a personal computer, an embedded system performs one or a few pre-defined tasks, usually with very specific requirements. Since the system is dedicated to specific tasks, design engineers can optimize it, reducing the size and cost of the product. Embedded systems are often mass-produced, benefiting from economies of scale."

    ...

    "Physically, embedded systems range from portable devices such as digital watches and MP3 players, to large stationary installations like traffic lights, factory controllers, or the systems controlling nuclear power plants."

    What I am trying to address is the concept of a computer that is embedded in the boat and dedicated to boat functions so I think the term is used appropriately within the definition. In addition, PC/104 systems are a major player in embedded systems. Doing a search on "PC/104" at www.embedded.com yields 115 returns. Doing the same on "Zigbee" yields 63 hits.
     
  10. TerryKing
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    TerryKing On The Water SOON

    Hmmm... Embedded Hmmm....

    Portager, I can see both sides.. Hmmm...

    Assuming a PC-104 system runs a PC Operating system like Win98 or WIN-XP, and therefore the user can install and run new software, and can use the MultiProgramming environment, is it different enough from the "Embedded System" concept in which it is "completely encapsulated by or dedicated to the device or system it controls." that it should have a different 'Label" ??

    I guess a PC-104 system could be used to implement a classical Embedded System, running out of ROM or Flash at power-up and unchanged by the user, right? But if it's running a PC O/S maybe it's in a different category?

    I just want to reader of this stuff to be clear on what we mean....

    What do you think??
     
  11. TerryKing
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    TerryKing On The Water SOON

    Moving this part of the detailed discussion??

    Portager, I'm thinking we should move this level of discussion to the "Onboard Computer" discussion thread connected to the Wiki. Agree?
     
  12. Tim B
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    Tim B Senior Member

    ummmm.... Why would you run an MS operating system on an (effectively) embedded system. That would seem to be asking for overhead and instability near seawater. Surely running a Linux kernel would be preferable by far.

    Tim B.
     
  13. TerryKing
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    TerryKing On The Water SOON

    Why a PC OS??

    Specifically to be able to use advanced, free navigation software like OziExplorer, integrate communications/weather receivers information, to allow a DIY software person to integrate multiple applications in a shipboard system, to allow use of the system at anchor for lots of other available applications. There are a number of high-end available systems that have WIN-XP as the OS. I'm not great microsoft fan, and Linux / Ubuntu may well be a good choice for some boat applications.

    A true Embedded System is something that I could write and integrate. But I'd still probably have some else's multitasking kernel. I bet it would be 100's of hours of work, and with the testing I could do I'm not all that sure that it would be more reliable than a very clean, minimized WIN-XP based system.
     
  14. Portager
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    Portager Senior Member

    TerryKing;

    Yes, I agree we should move this discussion. Just tell me where, or provide a link.

    You have a good point on the term embedded computer. PC/104 processors can run Win whatever or they can run Win XP embedded, Linux, ... Since most users wouldn't be using an embedded OS using the term embedded computer would be confusing. Maybe we should coin a catchy and descriptive name?

    Tim B;

    The disadvantage of using any embedded OS is; installation and set-up is too complex for most DIYers, getting support in remote areas could be difficult and in the case of Linux the lack of compatibility testing means interoperability is by guess and by golly.

    Win XP embedded (XPe) is a modular version of Win XP and excellent choice for PC/104 Computers. Windows has an application that allows OEM developers to load just the modules that are required for the embedded application. This strips out all the unnecessary components, allowing the system to boot from a flash drive, reducing boot/reboot time and minimizing the potential for conflicts. The problem is configuring XPe requires a $990 application to set it up (a small one time fee for an OEM, but a big added cost for the DIY user) and Microsoft licensing restrictions prevent it from being deployed on to standard PCs.

    The dirty little secret of Linux is nobody is paying for compatibility testing (Microsoft doesn't test Win compatibility either, but Windows is so common that most manufacturers do their own compatibility testing at least for the current versions of Windows) and many expansion modules do not include an application programming interface (API) for Linux.
     

  15. Tim B
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    Tim B Senior Member

    If the "DIY" user is building an embedded system, then the chances are that they know what they are doing. Linux may not be familiar, but shouldn't pose too much of a problem to learn (at least the basics). There is also a not inconsiderable support network (if you're on land) and if you have problems at sea, it's unlikely to be a software fault.

    The last time I asked a rep for a particular XP based software package to give me a demo, the machine hung and had to be rebooted. That wouldn't give me much faith in using it.

    As for Lack of compatibility testing, do you mean for hardware or software? Yes, software often has to be re-compiled, but from a hardware point of view, Linux runs on more chipsets than anything else (ever).

    see:
    http://www.linux.org/projects/ports.html

    It is worth noting that there are now embedded (or at least SBC) systems that come with a hardware-specific Distro from not a lot more than Microsoft's runtime licence!!

    I would advise that you read this page carefully...
    http://msdn2.microsoft.com/en-us/embedded/aa714410.aspx

    Please note, though that information regarding Linux from microsoft is wildly innaccurate. There are a lot of people around who are very afraid of a genuinely open operating system (and they have their reasons), and are very prone to making wild claims extolling the closed-source method (especially in the server market). Scepticism is a good thing, undoubtedly, just don't believe everything you here from the big organisations because almost all of it is propaganda sold as information.

    Cheers,

    Tim B.
     
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