335x LCD Setup Instructions¶

Typically Critical Link provides the LCD display kits as a complete kit including the necessary MitySOM-335x Development Kit Board. However the XGA and VGA displays can be added on to a standard baseboard only dev kit at a later time and these are the pertinent instructions to complete this update.

1) Complete the hardware assembly as directed in the "335x Display Kit Hardware Setup.pdf" guide, attached below.

2) For VGA display kits you need to update the uEnv.txt file on the dev kit SD card to change the video resolution to 640x480. The default resolution of the kits is 1024x768 so if you have the XGA display kit skip to step #4.

An updated uEnv.txt file has been attached to the bottom of this wiki.

To edit the file yourself from within Linux on the dev kit or in a Windows/Linux PC perform the following steps:

A) Open the uEnv.txt file from /media/mmcblk0p1/ using 'vi' or another utility. If using a windows PC the "boot" partition should be shown once inserted. You can use notepad to make the changes.
B) Change the "bootargs" line to read

bootargs=console=ttyO0,115200n8 video=da8xx:bpp=16,mode=640x480

C) Change the "optargs" line to read

optargs=video=da8xx:bpp=16,mode=640x480

D) If using 'vi' issue a "wq" to exit and save the file or if on a PC save the changes and safely eject the SD card.

3) Place the modified SD card into the development kit and/or reboot.

4) Make the touchscreen driver load on start-up of the "Matrix GUI".

From the serial port of your development kit please issue the following "sed" command which will modify the script file for you:

sed '/tsfile=\/etc\/pointercal/a sleep 1' /etc/init.d/matrix-gui-2.0 -i
sed '/tsfile=\/etc\/pointercal/a modprobe ti_tscadc' /etc/init.d/matrix-gui-2.0 -i

5) Copy the attached "backlight" file to your /home/root/ directory. You can use Ethernet and SCP from Linux or download WinSCP (http://winscp.net/eng/index.php) to copy the file from windows over the Ethernet. Alternatively you can use the following single line command to set the brightness from a value of 0 (min) to 31 (max), replacing the [0 to 31] with a single number such as 20:

echo [0 to 31] > /sys/devices/platform/tps6116x/backlight/tps6116x/brightness

Unless this command or script is added to the system start-up routine it will need to be issued after each boot as the backlight driver is reset at that time.

6) At this time your LCD should be displaying the matrix GUI at the designated brightness level. However the touch screen will still require calibration.

7) Touchscreen calibration (from the Linux serial console)

A) Remove any saved touch screen pointer calibration files

rm /etc/pointercal
rm /media/mmcblk0p1/pointercal

B) Stop the matrix GUI application so the touchscreen calibration routine can be run

/etc/init.d/matrix-gui-2.0 stop

C) Restart the Matrix GUI

/etc/init.d/matrix-gui-2.0 start

You will be directed to touch a [x] at 5 locations of the screen. Do so with either a pen cap or your finger as accurately as possible.

8) All setup should now be complete.