New kid on the block

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tsaiho
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New kid on the block

Post by tsaiho »

Hello everyone, and a shout-out to my two (at least) fellow hams here.

    I've been shoehorning Linux onto small tablets for a while - a masochist's hobby, but there it is! After trying to get something to run on a PenCentra 130, the DT366 seems like a dream, with its capability to boot from USB and its relatively standard peripherals.

    I have managed to put new LIon cells into the unit; Walmart was liquidating a $50 digital picture frame (with rechargable LIon cell) for $7, I bought four and was pleased to see they were slim enough to fit into the DT366. I paralleled 2, then used two of those paralleled units in series to bring the voltage up to 7.4 volts. Battery life is about 1.5 hours. The cells had on-board thermostats and charging circuitry. I just ran the red wire (from the original DT battery) to plus, the black to minus, and the yellow wire to ground via a 100K resistor (this makes the charging lights work).

    I'm using Debian, and it's all working fine except for the touchscreen, which does respond but has its Y axis reversed (when I move the stylus up, the mouse goes down.) I've included  "SwapY" "1" in my xorg.conf under the penmount 'Input Device' section, but it seems to have no effect. Anyone have any ideas?

    A reminder to anyone who feels themselves butting up against the 520 Meg memory limit - you can easily move any partition of your Linux install 'offsite' and onto a CF card. My /home and /usr partitions are on an 8G CF card - those are the biggest. Easy instructions here:

http://www.go2linux.org/how-to-move-hom ... -partition

    just remember to edit /etc/fstab and keep an empty, dummy directory with the same name on the boot drive.

    A pleasure to be here.

    Tsaiho
volkswagner
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Re: New kid on the block

Post by volkswagner »

Welcome,

Great work with the battery, I love a good bargain, with a challenge even better!

Have you moved your /usr directory?  I tried moving it in the past, but got errors on boot, due to CF-flash drive not activated early enough on boot.  There is a fix for this with a custom init image.  I am just wondering if you did successfully do this without the, custom init image, and if so what kernel are you using.  In fact with the custom init image you can put /boot on the internal flash, and put / on the CF.  It seems to be a significant performance hit.  I think the sweet spot is to put /var and /usr on the flash.

For the touch screen, I had the same issue.  After a good calibration with at least 9 points it will correct itself.  I had a hard time with the calibration, it seemed to stall or lock up, in fact it was just taking a long time, and did not move to the second point immediately after I hit the target.  So what was happening, was I hit the target too many times, causing bad data.  Be patient with the calibration utility and only hit the target once in each position.

Cheers,

eric
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tsaiho
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Re: New kid on the block

Post by tsaiho »

Hey Eric,

      I had looked on http://www.emdebian.org, but I think I ended up with a standard Debian netinstall iso burned to a CD. Install startup recognized the Cisco card and I was able to install what I wanted via a repository, choosing a minimal, no X install and adding xorg and icewm manager later, after I moved my /usr and /home directories. Specify 'noacpi' on the install bootup line; Debian has a bug involving finding the install media in the middle of a lengthy install. An apt-get install of "xserver-xorg-input-penmount" will get the screen running. Good luck!

Peter
tsaiho
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Re: New kid on the block

Post by tsaiho »

... and thanks so much for the tip about screen calibration - it worked!
volkswagner
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Re: New kid on the block

Post by volkswagner »

Glad you got the screen working.

Can you tell me the kernel you are using?

Please post output of:

Code: Select all

uname -a
That is great news, that you did not need to create a custom init.  I tried using symlinks, perhaps that is the difference.  With a small Flash drive, I did not want too many partitions with some wasted space, and partitions too small with potential for filling up.

Here is mine

Code: Select all

2.6.26-1-486 #1 Sat Jan 10 17:46:23 UTC 2009 i586 GNU/Linux
Here are the directories I moved using symlinks.  Check out var/cache...That darn apt can really eat some disk space.

Code: Select all

sudo du --max-depth=1 /hdc5/var -h
12M	/hdc5/var/log
62M	/hdc5/var/lib
155M	/hdc5/var/cache
228M	/hdc5/var

66M	/hdc5/usr/bin
201M	/hdc5/usr/share
266M	/hdc5/usr

I did get some side effects using the sym links.  Such as installing firefox got a double symlink to launch, causing it to fail...symlink to a symlink.  I was able to fix it, but it took a while to debug the problem.
Nothing is ever easy, but if it is difficult you must be doing it wrong.
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