Small Linux HW to be carried in a model airplane

I think you can do most of that with a Gumstix:

Leon

--
Leon Heller, G1HSM
http://www.geocities.com/leon_heller

how small ?

Pozdrawiam.

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Like ninjas, true hackers are shrouded in secrecy and mystery. You may never know -- UNTIL IT'S TOO LATE.

Must be a fairly hefty model, dragging along that printer, 4 RS232 peripherals, and a long Ethernet cable, not to mention lifting them all. Are you really sure you aren't overspeccing things a hair?

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The printer port was for digital I/O, not for a printer. At least that's what the phrase "for digital I/O" means to me.

There are many small RS-232 peripherals out there. An RS-232 peripheral need be no more than one or two chips.

That's likely for programming, configuration and upload download of data files.

I would guess he knows more about what he's trying to do than you do.

I know of a model airplane that carried a pretty full-up PC104 Linux system with an RF modem, video and still cameras, GPS receiver, gyros, air-speed and temp sensors, etc.

It sounds like his specs aren't much different.

--
Grant Edwards                   grante             Yow!  HELLO, little boys!
                                  at               Gimme a MINT TULIP!! Let's
                               visi.com            do the BOSSA NOVA!!

In other words, he is over-specifying. There is no need for ethernet for those purposes. He can do it all through one of the RS232 ports. He shouldn't add weight to his airplane for functions that he can do without.

On Usenet, that would often be a poor guess.

And that 45 second reboot will kill you on landing approach (: Just hope the watchdog doesn't have to fire.

In all seriousness, have you considered DOS instead?

I think one gets linux prompt in about 4 or 5s in a PXA255 like SBC as long no boot delay is programmed in the boot loader and carefull choice of filesystem (therefore no JFFS root fs), boot scripts and application is made. Someone (I think Montavista) even states almost instantaneous (less than 1s) boot up is achieved with execute in place patch. Haven't tried it though. Still it can be as long as 45s in the context presented.

Regards.

Elder.

8 MB @ 10 kB/s = 800 seconds = 13 minutes. Maybe he has other things to do than waiting for serial file transfers...

-- Best Regards, Ulf Samuelsson snipped-for-privacy@a-t-m-e-l.com This message is intended to be my own personal view and it may or may not be shared by my employer Atmel Nordic AB

Why would he have to move 8MB even once? An embedded system to control a model airplane shouldn't need to move that much data. A good, fast linux system can fit on a single floppy, and there is no good reason to collect data at more than 10 channels at

5 16-bit samples/sec each, that's 200 bytes/s - 360K/hour.

Have a look at this site for some ideas.

It is normally there to load the operating system and a flash disk Linux fit compressed into 700 kB, but if you for some reason like to program in PERL, then it quickly adds up. You will obviously not fly with an Ethernet cable attached, but you could have a digital camera which takes pictures, which you want to download once its landed. If that is the case, then maybe he would want to download 256 MB. Another alternative is for debugging purposes. Some systems run considerably better if Ethernet is attached.

-- Best Regards, Ulf Samuelsson snipped-for-privacy@a-t-m-e-l.com

Firstly with 4 RS232 ports you don't know what he is collecting data from. Secondly no A/D was specified. Thirdly the flight time is not known. Fourthly if any camera is involved for image capture the data size is exponentially bigger.

Personally I would if possible save to CF Flash and use that to transfer data.

The cost and weight of an ethernet port is likely to be the same or less than the CF card and mounting hardware.

Unless parts of the hardware can be put into very deep standby when not in use (USB, Ethernet, CF Flash) his real problem is going to be power consumption, as this will have more effect on weight wrt the battery size to be carried.

Downloading data sets after landing again is a good idea as in most countries model aircraft do not have wide bandwidth telemetry channels,

10Kb/s with modem chips is the highest you can get on allowed channels. Saving to non-volatile memory whilst in flight is also a good idea to avoid problems with power glitches/loss for whatever reason.

Some of the bits might be overspeced, most likely with use of optional USB and Linux. Then again it is not stated whether this is a control or monitoring application and how much.

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It doesn't take much video to fill up 8MB.

What about data from cameras?

--
Grant Edwards                   grante             Yow!  I once decorated my
                                  at               apartment entirely in ten
                               visi.com            foot salad forks!!

Sure we do. He is collecting data from a model airplane.

I wrote "bits." I never specified that they were ADC bits. Whatever kind of data he aquires, it ends up as bits.

Sure it is. It is limited by the weight of fuel and the weight of providing power for the board. Assuming a special kind of model airplane ythat flies for many hours without asking is no way to do a preliminary spec of an onboard computer. the default assumption should be a normal model airplane.

Now you are assuming a camera just to defend there being an ethernet port. Why not streaming video? Why not assume an onboard hamster with life support in case the plane flies too high?

Indeed. Then again, maybe he does have an onboard camera and hampster...

If you are going to add on things that he never said are on the airplane, why stop at a camera or two? Why not just assume full

360 degree IMAX-format streaming video?

There are plenty of "normal model airplanes" that can fly for quite a long time. On a decent day, a glider can fly for hours. Eventually, the receiver/servo batteries run down, but the energy density of LiPoly cells is getty pretty high.

Putting cameras in model airplanes is a pretty popular thing to do.

It's been done. The model I'm thinking about was a glider lifted to about 50,000 feet by a small weather baloon, and then released. It flew semi-autonomously for a couple hours and then landed at the launch site. It had both a web-cam and a

35mm still camera. That plane had an RF modem link so the ground station could get live telelmetry and video.

That would be somethign new.

I wouldn't be at all surprised if he's planning on putting a camera in the plane. The hampster would be a bit odd.

--
Grant Edwards                   grante             Yow!  Did an Italian CRANE
                                  at               OPERATOR just experience
                               visi.com            uninhibited sensations in
                                                   a MALIBU HOT TUB?

Because cameras in model planes aren't unusual. 360 degree IMAX-format streaming video would be pretty unusual. Especially since the "format" is 75mm prints.

--
Grant Edwards                   grante             Yow!  .. over in west
                                  at               Philadelphia a puppy is
                               visi.com            vomiting...

Or non-existent. I've never heard of it. IMAX is usually shot with off-the-shelf Hasselblad still camera lenses and a custom made camera body. No Hasselblad lens can do 360 degrees. And as you implied, the format has *nothing* to do with video.

Especially

Actually transparencies. Admittedly, the working copies are usually referred to as "prints"