Peripherals/Touch Screen

Technology

Different touch screen technologies:

• 4-Wire Resistive
• 5-Wire Resistive
• Capacitive
• Surface Acoustic Wave
• Infrared
• Strain Gauge technology
• embedded ccd in panel - can't find link but light detectors can be intermixed with light generators, maybe on an oled display, so the computer can detect when light reflected
• A simple light sensor could also work as a display pointer. A tethered pen could detect flashed target boxes, like the old Nintendo Light Gun. For continuous drawing, the screen could flash through a series of patterns where the pen either sees light or dark. Each screen location would thus have a unique binary code flash through it, which would be reported by the pen's narrow light sensor. This screen scan will start in a small box near where the pen was last to reduce search time, and the eyesore of flickering. -- Nintendo wii remote has been hacked to provide multi touch interface-- http://gizmodo.com/gadgets/clips/wiimote-hack-is-wireless-multitouch-tv-321329.php

Apparently most PDA’s use 4-Wire Resistive touch screen technology. However I am not positive on this.

Adding a Touch Screen to the XO

The XO has a 7,5 inches display, so is quite hard to find. An alternative is to buy an 8 inches no wide touch screen, I have bougth mine at http://www.iiic.hk.cn/ Then you have to open the XO computer and remove the screws in the lcd corners, then remove the rubber over them to obtain more space between the top plastic and the display. The touch screen comes with an usb controller, that we soldier inside the XO USB port as you can see in the pothograph. We could obtain some free space, over the display as you can see in the photograph.

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wget http://dev.laptop.org/~dilinger/testing/kernel-2.6.25-20080925.1.olpc.f10b654367d7065.src.rpm bash-3.2# mkdir /usr/src/redhat bash-3.2# mkdir /usr/src/redhat/SOURCES Compilando El kernel module de Touch Kit

wget http://dev.laptop.org/~dilinger/testing/kernel-2.6.25-20080925.1.olpc.f10b654367d7065.src.rpm bash-3.2# mkdir /usr/src/redhat bash-3.2# mkdir /usr/src/redhat/SOURCES bash-3.2# rpm -ivh kernel-2.6.25-20080925.1.olpc.f10b654367d7065.src.rpm yum install redhat-rpm-config yum install m4 yum install rpm-build yum install unifdef yum install tar rpmbuild -ba --define "dist olpc1" --define "olpc 1" --define "head dc5079fafb767e4" --target=i586 /usr/src/redhat/SPECS/olpc-2.6.spec

en el make del touch usb cambiar KDIR por KDIR := /usr/src/redhat/BUILD/kernel-2.6.25/linux-2.6.25.i586/ da error al hacer make, se soluciona agregando {} al final de la tabla, ver http://forum.eeeuser.com/viewtopic.php?pid=175102

make!

pruebas para exportar las variables de entorno:

cp tkusb.ko /lib/modules/ mknod /dev/tkpanel0 c 180 180 add the following to /etc/rc.local Code:

1. 1. TouchKit kernel module section begin ##

rmmod touchkitusb

1. This module may be renamed “usbtouchscreen”.

insmod /lib/modules/tkusb.ko

1. for Kernel 2.6.x only.
   1. TouchKit kernel module section end ##

modifique /etc/profile para agregar LD_LIBRARY_PATH modifique /etc/bash.bashrc agregando el contenido de libs.sh

External Links

• Touch Screen Technology