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[Bastian]

Hi,

I want to have the high resolution black and white screen and backlight. I had the line to type into terminal, but lost it when my MacBooks hard drive died. Can somebody help me out.

Thanks

[Tjelfe]

Hey Bastian,

since the color is produced via hardware filter this would be impossible.
btw: The resolution is always 1200x900.

cu
T.

[Bastian]

Found it!

ok, the resolution is always 1200x900 and the reflective mode (and its crispness) can't be used with backlight, still:

su
echo 1 > /sys/devices/platform/dcon/output

will put the screen in grayscale mode with the backlight on. This makes the screen less blurry and is great for reading pdf in bed. Using the screen brightness buttons turns it off again.

Bastian

[Ben]

su
echo 1 > /sys/devices/platform/dcon/output

It works, but you have to switch away from the Terminal to see that it worked.

[magnuan]

Nice.
It seems to turn off some anti-aliasing filtres. Very usefull for viewing b/w line art.
Made some scripts for switching between modes:

Code:

#/bin/bash
iofile="/sys/devices/platform/dcon/output"
while read line; do cur_mode=$line; done < <(cat "$iofile")
if [ $cur_mode = "0" ]; then
        new_mode=1;
       echo Going B/W
else
        new_mode=0;
       echo Going Color
fi
echo $new_mode > /sys/devices/platform/dcon/output

To be able to run this script as non-root, I added this to /etc/rc.local

Code:

chgrp olpc /sys/devices/platform/dcon/output
chmod g+w /sys/devices/platform/dcon/output

I don't think this would be to much of a security risk (please let me know if you dissagree)
There still seems to be a lot of unused keys on the OLPC-keyboard, so untill it comes into better use, I mapped the "two-squares"-button to this script with xbindkeys
~/.xbindkeysrc

Code:

# Videomode (color/ BW)
 "/bin/bash /usr/bin/videomode"
 c:224

Where /usr/bin/videomode is a link to the script for switching modes.

[Tjelfe]

Really nice! I didn't know that.
Thanks for sharing.

CU
T

[XOIOWA]

I'm not exactly a newbie... but I'm far from expert.

I'd love to to the keybindings as shown here, but I'm missing something.  I've tried, but even as root, I'm getting permission denied when I run /usr/bin/toggle_screen_color  (that's what I named my symlink)

Could you please provide more detail about the file permissions, and how to actually do the keybinding?

Thanks in advance,

[magnuan]

Sounds strange.
Did the rc.local script work as intended?
Check:

Code:

ls -l /sys/devices/platform/dcon/output

Mine reads:

Code:

-rw-rw-r-- 1 root olpc 0 (file date) /sys/devices/platform/dcon/output

Are you able to switch modes manually with (both as olpc and as root):

Code:

echo 1 > /sys/devices/platform/dcon/output

What about the permissions for your script and symlink?

I am running "OLPC build update.1 703", haven't tested it on any other builds, but as long as echoing to .../dcon/output works, I can't see why the script shouldn't.

[XOIOWA]

I'm on build 656.

ls -l /sys/devices/platform/dcon/output
-rw-r--r-- 1 root root 4096 <date&time> /sys/devices/platform/dcon/output

I found out that I can change modes manually only as root, so, I must have missed something in the file permission there.  chmod g+w?  I guess I'm not familiar enough to know those arguments.  I'll have to check that later.

[XOIOWA]

I did some checking, and found that I had done the rc.local incorrectly.  So, I fixed that.  Now I can run my script as root, or as a user, but only if I'm in the same directory as the script, and I use this command:  ./toggle_screen_color

It doesn't seem to want to run from the symlink in /usr/bin.  Whenever I try that, I get a Permission Denied message, no matter if I'm root or user.

Any hints?

[magnuan]

Try
> sudo chmod a+x /usr/bin/toggle_screen_color    (or the name of your symlink)
From what you write, this shouldn't be necessary, but it's worth a try.

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