Discussion- Multi-purpose Onboard Computers

[Pericles]

Terry,

It's not at all surprising you were cold. You were lucky to eat.

http://news.xinhuanet.com/english/20...nt_7698015.htm

Regards,

Pericles

[masalai]

http://e.webring.com/hub?page=1&ring=gpsusers&list
http://tuxmobil.org/linux_gps_naviga...lications.html

Would either of these be of assistance on nmea protocols? I have them bookmarked to check out for new releases on gps / computer interfaces on Linux...

The non release and "personalisation" by various brands make the nmea protocol seem to be a "minefield of issues" - have you got the gps I sent to Terry - or is he using it to do interface work...

[Tim B]

You are quite right, the parts of the NMEA system that are non-standard are a pain. Some outputs have been reverse-engineered, and some are still a mystery to all but the manufacturer. NMEA, though has got well published sentences, which all gps (and other) devices must transmit if they are going to claim to be NMEA-compliant. Therefore, for outputs like position, speed and track, all GPS units will output the same sentences ( $GPRMC ). In fact, this is the only sentence that OpenPilot currently handles, mainly because it tells me everything I currently need to know.

The problem with adding extra NMEA sentences is simply time, and the ability to test them. Modifying the code is not hard (just parse the correct sentence and emit a signal) so most coders should be able to do it. The difficulty comes in handling the data after it has been emitted from the GPS routine. Magnetic heading for example, could be plotted on a gauge with track (which is what happens at the moment). Alternatively, you could subtract track and heading to give the course error.

if anyone wants to browse the NMEA code it is here:

http://openpilot.cvs.sourceforge.net....3&view=markup

I will (at some point) be adding capability to handle satellite sentences (GPGSA & GPGGA) and plot them on some sort of graph/globe as you would find on a hand-held GPS. I also intend to add a few more gauge-styles, so I hope we will see part-filled rectangles, and rectangular tape-style gauges. I also want to add green/orange/red sections to the gauges for operating conditions.

There is a lot of work yet to do, and as this is an open source project, I invite you all to join in!!

Cheers,

Tim B.

PS. You might want to have a look at this site too! http://aprs.gids.nl/nmea/

[erieslabhunter]

I don't mean to jump in but I don't want this thread to die. I have tried focusing on the 9 pages of great info but after reading through much seems to just be a blur I will read more focused in the morning (been a long couple days on rough water). I will just highlight a few issues that were at one time issues and they may have been resolved just not sure...

Power Supply - As many may realize the power to any motherboard is regulated at 12V, the only issue is the start-up and shut down. This can't simply be rigged to the ignition, but there are some special 12V power supplies that are less than $100 used in carputers.

Solid State Drives - While solid state drives are becoming ever cheaper the easiest solution is the USB flash drive. You can easily pick up 8GB for less than $100 these days, no need for moving parts nor the expense of a SSD.

Embedding XP - I don't mean to sound ignorant but if there is already work being done in Linux why try to port it to XP? Not to mention Linux can EASILY fit onto a puny little 512mb USB with loads of software on top of the OS.

I have a question on the marine radios... I know you can get XM via USB but are there any VHF interfaces for computers available to civilians?

[TerryKing]

Originally Posted by erieslabhunter

I don't mean to jump in but I don't want this thread to die... Power Supply - ..Solid State Drives - Embedding XP - marine radios...

Eric, I apologize for not keeping this thread up. I am living in China and things have pointed me more inland the last few months more than I expected. I'll try to get back here more often.

You raise good issues. Briefly,
- Yes, the "CarPuter" power supplies are a good answer, small, reliable, tolerant of voltage surges. I have a couple on the test bench.

- Solid State Drives. I agree the USB drives are a cost leader.. but a 100 Gb notebook drive is not too expensive, very durable etc. If something like 16 GB total is enough for an application, Flash may be good. THere ARE still issues about how many write-cycles are possible, etc.

- XP and (not VS) Linux: No answer fits all. For me, I have favorite applications like OziExplorer that need XP. Virtualization of Linux or XP on each other may be a fits-all answer. Having talked with friends working on Virtualizing Windows on Power PC, I'm a little leery of the complexity.

- Marine VHF: There are specialized modems (usually called TNC's (Terminal Node Controllers)) that interface VHF and Short-Wave(HF) radios to computers. There are whole books on this. Do a little Google / Wikipedia
http://en.wikipedia.org/wiki/PACTOR etc.

This whole subject is coming together, I believe, hardware and software.

[erieslabhunter]

I agree write cycle on USB drives could be an issue. I know dozens who use them as a sole drive for their OS, and I do not think the life cycle for the rewriting is much of an issue in real world situations but would hate to be stranded in fog when it does happen to strike. I am sure that is the exact moment it would happen and the only time it would ever happen to me! Realistically the SSD life cycle is not much better if at all according to the specs I seen on them 8 months back. 2.5" laptop drives are reasonable as an alternative I agree on.

As the theory goes on the auto-pilot/GPS features what type of software are we in need of? What type of hardware would we be seeking for the auto-pilot too?

Are there yet any open source sonar (fishfinding) applications available yet?

As far as the PACTOR system you linked to goes, that seems more inline for data over the VHF networks and channels such as email. I meant actually tuning to the channels and using the radio itself for analog voice transmission and reception. I mean really we are talking about an all-encompassing computer to handle everything, right? If I wanted a computer that could do everything, I want it to do everything not everything except the radio I need to buy.

Obviously I am not worried about seriously having to buy an additional piece of hardware like a GPS unit or a little radio, just the idea of it is the reason I ask. For data I almost always have a cellular signal on the lakes I'm on, I don't sail.

[Tim B]

Openpilot will port to XP without too much trouble (see some other thread that I posted on on the subject). It's an inconvenience, but it is possible. I will not be supporting WIN XP outright, with the exception of the SerialIO module which will be supported under WinXP and Linux.

Small disks and OS: I wouldn't even worry about running Linux from a Compact flash drive or similar.it'll do it with no hassle at all. You will only have problems if you're logging a lot of data to it (in which case use a different disk/card!!)

SONAR - not yet, for the same reason as RADAR. Primarily, of the few people that have them, even fewer are in the hands of enthusiastic coders, and the IO mechanisms are apallingly badly documented. It would be interesting to look into though.

Radio - well, possibly, what's the interfacing? DSP sets need an NMEA GPS feed which is not too hard. As for voice, etc. it may be a direct feed.

Autopilot is relatively easy, you just need some algorithm and an NMEA output.

The whole idea of OpenPilot was to set it up so that you can just add a module to it. so if you need a RADAR display, you pick up the Mapping module and add a RADAR class to it to handle that display mechanism. If you want a radio interface, you can create a new module for it and there you go.

Cheers,

Tim B.

[Hovercraft]

On the subject of cooling... Just wondered if the Peltier type of Thermoelectric devices might work? The type that are used in portable fridges. I'm not sure of the current draw - and agreed it would only be suitable for those with power to spare... You could rip one out of a mini fridge or coolbox (ones which have a fan each side of the device are best) and house your computer etc in an sealed / insulated compartment. Just a thought!

[BillyDoc]

Hovercraft,

Lots of good Peltier info here: http://www.peltier-info.com/info.html

The page is confusing, you have to scroll down to find the info. Oh, and to answer your question: You bet! Some enthusiasts put Peltier modules between their CPUs and the heatsink to get them cooler than they otherwise could so they can overclock them. The modules have a lot of things going for them, but they are not very efficient, unfortunately.

BillyDoc

[marshmat]

Thermoelectric cooling? Sure! If you have the power, and the money, to spare.

One of the computer shops around here sells the Peltier-effect CPU cooler BillyDoc mentions for about $160. That's a fair whack of cash compared to the $14 that the normal heatsink/fan costs, or the $36 that the really fancy heatsink/fan costs. For serious gamers who overclock to the limit, it's useful; however, they are not very efficient. It takes a fair bit more power to drive a thermoelectric cooler than to drive a normal air conditioner or heat pump of similar capacity, hence why you don't see them in fridges very much. For portable coolers that are already well insulated and don't need to get things cold- only keep them cold- thermoelectric is a good solution.

[BillyDoc]

Wow Matt! That's a hell of a markup! Take a look here for a more "reasonable" price: http://search.digikey.com/scripts/Dk...tier&x=15&y=14 Their most expensive Peltier module (4 cm x 4 cm) is $17.82.

And Digikey isn't usually what I would call cheap.

Bill

[masalai]

If you need that much cooling, don't use the nitrous in that big V8 engine? - and what have you got that needs so much cooling? My AMD has just a little fan on top of the cpu, in case ambient exceeds 42deg Celsius (107.6F) and I don't intend going to the middle of a desert to try it out.... (it is a Turion tl60 mobile) - - my notebook had a heating issue using intel, as sadly I could not get it with AMD due to anti-competitive practices a year ago.....

[burgoynebc]

I have been trying to work out very cheap ways to use a laptop for navigation. After motoring 120 miles in zero visability fog in northern BC, the experience has made me a true believer in the value of this approach to Nav. I have a USB GPS and a 19" flat LCD display and use the free download chart system "seaclear". I have found this to be excellent and the Canadian charts, although not free like in the USA are readily scrounged. My next step is to tie this into a very old woodfreeman autoplot. The wood freeman is totally electrical - no PC boards or electronics so subject to failure in salt air. I am wondering if anyone has come up with a really cheap but robust interface to take the usb nema 0183 laptop output and convert it to a simple 12v left/12v right input to my autopot (via an H bridge DC motor reversing circuit).

I am also trying to find ways of stripping the laptop down and building it into the boat's cabinetry such that the harddrive (use flashdrive to boot XP), screen, keyboard and other fragile devices are removed. Has anyone tried to do this?

[masalai]

I am in the process of putting together a "mini desktop" using an ITX motherboard fitted with AMD turion-mobile cpu, 4gig ram, 500gig HDD lots of usb ports and drive 2 to 4 separate screens (not "clone" images of the first) using Linux Mint.... I will post the info on the motherboard when it is done - hopefully within the week

The system will multi-task for me when I finally get my new boat sorted.... I hope....

[burgoynebc]

Does linux cut down the OS size so as to facilitate usage of a bootable flashdrive and allow removal of the harddrive from a laptop? Having dismantled mine several times it is all too clear to me that the retention and pinouts of standard laptop harddrives are not appropriate to usage onboards a sailboat, let alone the internal fragility of the drive itself.