homemade EFIS system and EMI

"jcpearce" wrote in message ups.com...
Thank you everyone for the input, now I am looking for some
prioritization. I received the new power supply from www.mini-box.com
and it is substantially better than the previous version
(http://www.mini-box.com/s.nl/sc.8/ca...it.A/id.356/.f ) however
I still get some noise in the radios. The new version is too big to
fit in the previous enclosure so it is sitting slightly apart from the
MB on its own.

I have started to jot down what the system wants to do, pictures and
status at
http://69.229.202.54:8080 Under the 'Image' folder one can see the
plane, the EPIA in the nose and the prototype ADC board.

So now I have a case that has to heavily part for the ATX power lines
to come into it & a non cased DC power supply. I have attached ferrite
beads to the power lines coming in/out with little improvement.

It takes time for many of the steps so I am looking for what you folks
think would be the 'biggest bang for the buck', or the right priority
to proceed with. (IE, build a brand new case for everything, build a
seperate case for the PSU, don't build a case right away but do X,Y,Z,
etc..)

Thanks once again for the brains helping noodle this over.


Check out this machine, only +5vdc required, linux capable...

http://www.diamondsystems.com/products/prometheus

I'm sure there are many more similar...

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Blueskies wrote:
"jcpearce" wrote in message ups.com...

Thank you everyone for the input, now I am looking for some
prioritization. I received the new power supply from www.mini-box.com
and it is substantially better than the previous version
(http://www.mini-box.com/s.nl/sc.8/ca...it.A/id.356/.f ) however
I still get some noise in the radios. The new version is too big to
fit in the previous enclosure so it is sitting slightly apart from the
MB on its own.

I have started to jot down what the system wants to do, pictures and
status at
http://69.229.202.54:8080 Under the 'Image' folder one can see the
plane, the EPIA in the nose and the prototype ADC board.

So now I have a case that has to heavily part for the ATX power lines
to come into it & a non cased DC power supply. I have attached ferrite
beads to the power lines coming in/out with little improvement.

It takes time for many of the steps so I am looking for what you folks
think would be the 'biggest bang for the buck', or the right priority
to proceed with. (IE, build a brand new case for everything, build a
seperate case for the PSU, don't build a case right away but do X,Y,Z,
etc..)

Thanks once again for the brains helping noodle this over.



Check out this machine, only +5vdc required, linux capable...

http://www.diamondsystems.com/products/prometheus

I'm sure there are many more similar...


All Right! Now that's what I call an embedded system. Actually I use
systems almost exactly the same as these in my line of work... Put Linux
on them too.
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Blueskies wrote:


Check out this machine, only +5vdc required, linux capable...

http://www.diamondsystems.com/products/prometheus

I'm sure there are many more similar...

Looks to be a nice system to play around with. It has the possibility of
handling both the data interface and computations. The main problem I see
with this system is no windowing system ie KDE and I think that was part of
his need.
John

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UJ,

Well, it doesn't come with a video card if that is what you meant,
however, that is a relatively simple matter to fix. PC104 video cards
are quite reasonably priced & even support 1/2 or 1/4 VGA standards.

Evan

UltraJohn wrote:
Blueskies wrote:



Check out this machine, only +5vdc required, linux capable...

http://www.diamondsystems.com/products/prometheus

I'm sure there are many more similar...


Looks to be a nice system to play around with. It has the possibility of
handling both the data interface and computations. The main problem I see
with this system is no windowing system ie KDE and I think that was part of
his need.
John


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He could also go with the Athena card instead. That does have VGA on it. And
it's a faster processor.

"Evan Carew" wrote in message
...
Well, it doesn't come with a video card if that is what you meant,
however, that is a relatively simple matter to fix. PC104 video cards
are quite reasonably priced & even support 1/2 or 1/4 VGA standards.

Pete Schaefer wrote:

He could also go with the Athena card instead. That does have VGA on it.
And it's a faster processor.

"Evan Carew" wrote in message
...
Well, it doesn't come with a video card if that is what you meant,
however, that is a relatively simple matter to fix. PC104 video cards
are quite reasonably priced & even support 1/2 or 1/4 VGA standards.

Looking closer at it the biggest shortcoming I see now is the lack of ram
the card only handles 32mb and Linux is very memory intensive and running
only a 486dx-100 mhz chip with that kind minimal memory it will be
relatively slow. Do you really want to watch a video screen at 1/2 or 1/4
vga resolution? I think the card would be great for his data acquisition
card and use the via card for the processor. at least he'd be using the
same operating system and compilers for both. Less to learn and get
confused with, I get very confused!
John

Look again at the specs. The Athena has 128mb on board, and uses a
400-600MHz VIA Eden.

"UltraJohn" wrote in message
nk.net...
Pete Schaefer wrote:

He could also go with the Athena card instead. That does have VGA on it.
And it's a faster processor.

Looking closer at it the biggest shortcoming I see now is the lack of ram
the card only handles 32mb and Linux is very memory intensive and running

Pete Schaefer wrote:

Look again at the specs. The Athena has 128mb on board, and uses a
400-600MHz VIA Eden.

"UltraJohn" wrote in message
nk.net...
Pete Schaefer wrote:

He could also go with the Athena card instead. That does have VGA on
it. And it's a faster processor.

Looking closer at it the biggest shortcoming I see now is the lack of ram
the card only handles 32mb and Linux is very memory intensive and running

My reference was to the Prometheus board that was suggested, and it does
look like a viable source for the data acquisition.
http://www.diamondsystems.com/products/prometheus

I have not looked up the Athena. Who makes it? Even the 128mb is pretty
marginal for Linux except possibly in the straight data acquisition mode.
John

In article et,
UltraJohn wrote:
Pete Schaefer wrote:

He could also go with the Athena card instead. That does have VGA on it.
And it's a faster processor.

"Evan Carew" wrote in message
...
Well, it doesn't come with a video card if that is what you meant,
however, that is a relatively simple matter to fix. PC104 video cards
are quite reasonably priced & even support 1/2 or 1/4 VGA standards.

Looking closer at it the biggest shortcoming I see now is the lack of ram
the card only handles 32mb and Linux is very memory intensive and running

With some care in kernel tuning, you can get the memory footprint *way* down.

The _real_ memory pig is the X server.

With a text-only display, it is *amazing* how much you can do in 'small'
memory configurations. 8 megs is _plenty_ for running a dedicated 'firewall'
box, for example, and a _386DX/33_ will handle a full T-1, in that
application, with cycles to spare.

I ended up ordering a Via TC motherboard as it will take up less space
than the CL with cumbersome DC converter and hopefully reduce RFI, and
if there is still RFI I have only one variable to contend with vs two.

I did not go with the PC104 format although I did look at this at
length. I already have considerable experience with the VIA now, a case
and airplane bay designed for it (17cm x 17cm) and a very lean kernel
tweaked for it. Also the VIA is a tad more mainstream with this
typically resulting in better doc and support for drivers. Also I can
boot off a write protected USB flash card (USB flash memory as IDE did
not work for me, too much data corruption in unexpected power off
scenarios). I don't know which PC104 have this ability. Anyone with
PC104 experience would probably argue with this, but I have had my fair
share in the past of getting odd behavior with a video, sound, ethernet
driver and having to slowly track it down. I know all the MB sensors on
the VIA are queryable in linux (ie CPU temp, all the voltages, etc..)

For me, memory is very important and 512Mb a mininum. Why so big when
my entire custom Linux distribution with X and Java fits on a 128Mb USB
flash card? As a Robert pointed out the kernel is a small memory
consumer, X is the real hog. And with potentialy complicated displays
this would grow even further.

Most importantly this distribution runs in entirely in memory,
there are no writes by the OS to the main USB flash card which is write
protected. As such there is no swap space, and hence any malloc calls
need to actually find real memory not virtual memory. Flash memory
degrades with each write, areas such as swap and log directories can
receive an enormous # of writes with often little effort. Some
benchmarks have shown corruption after only 10,000 writes. Having a
memory block go bad (which is just a matter of time given the nature of
Flash) can lead to odd/unpredictable behavior (the worse kind),
something I want to entirely avoid.

The secondary USB flash card, which is not write protected, holds the
log files and mp3 files. 'Non critical' files. I also wrote the data
logging program to only flush the OS writes every X seconds, not on
each log write. I could add an OS swap file to this partition but I
still could end up with corrupted swap space and the additional writes
would also shorten the life of the USB flash card. Additional memory is
cheap insurance (in additional $40) in avoiding these problems and has
an added benefit of performance.

If I was going to start from scratch I might go with the PC104 platform
but neither platform seems to be vastly superior to the other. And the
Devil you know...