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Linux Wacom Project HOWTO

7.0 - Tablet PC

The Wacom digitizer that is embedded in the Tablet PCs can be a serial or USB tablet. The USB Tablet PCs follow the same configuration steps as the other Wacom USB tablets. This page is dedicated to serial Tablet PCs.

The embedded serial Wacom digitizers utilitizes a special protocol IV, ISDV4. Similar to the conventional serial tablets, serial tablet PCs use a serial controller (UART). But, on older Linux kernels, they are not set to a logical serial port. They are effectively serial devices, but require special configuration (setserial) under Linux.

The good news is on newer Linux kernels, most serial Tablet PCs don't need the setserial step anymore since the kernel is taking care of them now. However, you still need to figure out which serial port your tablet has been mapped to before update the xorg.conf.

You can use xxd to see if your tablet has been mapped onto a serial port or not. To do so, follow the steps below:

[jej@ayukawa ~]$su
[jej@ayukawa ~]# xxd /dev/ttyS0  

Move your pen on your tablet PC. If you see output from the terminal while you move the pen, your tablet has been mapped to port 1. Quit xxd by Ctrl+c. Then ignore the rest of this page and go to (see Configuring X11) page. Otherwise, apply xxd to port 1 to 4. If none of them show output, you need to manually map the tablet to a serial port or update your kernel serial driver.

If you have installed the kernel source that your system was based on, check the source under drivers/serial to see if you have 8250_pnp.c or not. If the file exists, please add:

	/* Wacom tablets */
	{	"WACFXXX",		0	},

to the end of pnp_dev_table (or replace all entries that start with WACF). Then compile and install your kernel from source. Once you launch the newly installed kernel, your serial tablet should be mapped to a ttyS port. Use xxd to decide which port is associated with your device.

If your kernel doesn't have 8250_pnp.c or you don't like to rebuild your kernel, here is a sample command to set your port manually. The IO port is most probably different from your Tablet PC, which you have to figure it out. This is the trade-off for not updating the kernel serial driver.

[jej@ayukawa src]$ setserial /dev/ttyS2 port 0x93f8 autoconfig 

This command needs to be excuted with each reboot before X server starts.

You can add the command into one of your favorite start scripts. I normally add it into /etc/rc.d/rc.local. Here is how my rc.local looks like:

# This script will be executed *after* all the other init scripts.
# You can put your own initialization stuff in here if you don't
# want to do the full Sys V style init stuff.

touch /var/lock/subsys/local
setserial /dev/ttyS2 port 0x93f8 autoconfig 

After installing wacom_drv.o and other programs, such as wacomcpl and wacdump, restart X server. Now you can view raw tablet data by:

[jej@ayukawa util]$ ./wacdump -f tpc /dev/ttyS2       # Wacom digitizer on fake COM3

If your wacdump is from linuxwacom version 0.7.5 or older, issue [jej@ayukawa util]$ ./wacdump -f c100 /dev/ttyS2

If everything looks right from wacdump (see Using wacdump), you can update /etc/X11/XF86Config or /etc/X11/xorg.conf to load wacom X driver (see Configuring XFree86/X11R6).

Please note that in Wacom InputDevice section, the following 2 options are required for serial Tablet PC:

  Option        "Device"        "/dev/ttyS2"          # SERIAL ONLY
  Option        "ForceDevice"   "ISDV4"               # Tablet PC ONLY

Refer to Adding the InputDevices for more information.

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