User:MartinDengler

+	Software
XO
	13.2.11	2020-01-29
XS
	xs-0.7	2012-02-20

About Me

I program for a living. I got an XO to support the OLPC project and have a laptop for daily use.

I work with python and Fedora a lot.

XO/OLPC mini-projects

I'm interested in helping with:

* Implementing ebook mode (Trac #2954) 
* Sugar grabs too many shortcut keys (Trac #4646) 
* and anything else that looks interesting

Ambient temperature tracking

bash-3.2$ cat /ofw/openprom/model ; echo
CL1   Q2D13  Q2D
bash-3.2$ cat /boot/olpc_build
update.1 691
bash-3.2$ for f in /sys/class/power_supply/olpc-battery/temp* ; do (echo -e $f\\t ; cat $f) | paste - - ; done
/sys/class/power_supply/olpc-battery/temp               2783
/sys/class/power_supply/olpc-battery/temp_ambient               3900

bemasc explained things on #olpc [I edited out background chatter]:

bemasc: "ambient" means "ambient in the case"
bemasc: battery means in the battery compartment
bemasc: the "ambient" thermometer is on the motherboard
bemasc: not sure which chip
bemasc: they were trying to place in the antenna
bemasc: so that it would be far from the heat sources
mtd: bemasc: so I guess if I want to know the temperature outside the case, the lower of the two numbers is closer to that (though still quite inaccurate)
bemasc: the battery temp is closest, yeah
bemasc: if you have another thermometer, you might consider trying to work out the offset and correct for it
bemasc: it'll be different depending on whether the battery is charging or discharging, and how fast
bemasc: and it'll take at least a few minutes to stabilize
bemasc: so it's not easy, but it's also not impossible

Misc snippets to remember

Backlight and blurring switched off, makes some pdfs more readable:

su -c "echo 1 > /sys/devices/platform/dcon/output"

How to explicitly forget/add a WPA wireless network

If you want to forget/add a WPA wireless network explicitly, stop NetworkManager (/etc/init.d/NetworkManader stop) and edit

/home/olpc/.sugar/default/nm/networks.cfg

Screen battery status hint

Date: Sat, 5 Jan 2008 18:09:19 +0000
From: Martin Dengler <martin@martindengler.com>
Subject: Battery capacity in screen hardstatus line hint
To: devel@lists.laptop.org

[-- PGP output follows (current time: Sat 05 Jan 2008 06:23:51 PM GMT) --]
gpg: Signature made Sat 05 Jan 2008 06:09:19 PM GMT using DSA key ID 75C7D2F8
[GNUPG:] SIG_ID AwM6Me4nlHAq/mT0qRJbz79n4sk 2008-01-05 1199556559
[GNUPG:] GOODSIG 81B444DD75C7D2F8 martin@martindengler.com
gpg: Good signature from "martin@martindengler.com"
[GNUPG:] VALIDSIG 565C8F33ABF72DAA33DEB9CB81B444DD75C7D2F8 2008-01-05 1199556559 0 3 0 17 2 01 565C8F33ABF72DAA33DEB9CB81B444DD75C7D2F8
[GNUPG:] TRUST_ULTIMATE
[-- End of PGP output --]

[-- The following data is signed --]

Hi,

In case this is of use to anyone, I've put the battery capacity in my
xo screen instance's hardstatus line with this tiny script & screenrc
change:

---------- /home/olpc/bin/olpc_screen_status.sh
#!/bin/bash
# Author: Martin Dengler <martin@martindengler.com>
# idea from http://www.mail-archive.com/screen-users@gnu.org/msg00322.html
# based on battery info from olpc-logbat
#
B_INFO=/sys/class/power_supply/olpc-battery

while true
do
    CAP=`cat $B_INFO/capacity`
    echo b:$CAP%
    sleep 60
done
----------

....screenrc change:

---------- /home/olpc/bin/.screenrc
# run command forever and assign most recent output to string escape %1`  
backtick 1 0 0 /home/olpc/bin/olpc_screen_status.sh

# the ...%1`... part at the end is the important part
hardstatus alwayslastline "%{.bW}%-w%{.rW}%n %t%{-}%+w %=%{..G} %H %{..Y} %m/%d %C%a %1` "
----------

I'd be interested to know how to get at the ambient temperature sensor mentioned in section 2.4.1 of the CL1 hardware design specification PDF. I've had a look around /sys/class but nothing's jumped out at me.

Other useful OLPC hints

http://www.catmoran.com/olpc