setting xM LCD resolution at U-boot?

A few specific questions:

  1. What is the recommended way to set the LCD display resolution for a Beagleboard-xM with a BeagleTouch 4.3” display, running Angstrom?

  2. Are there compatibility issues between a kernel and rootfs files if I swap out kernels (uImage)?

  3. Liquidware’s website notes that the USB connector on the LiquidTouch screen is an extension of the serial port. Has anyone successfully used it for debug and are there specific kernel source changes required to make it work?

I’m using a Beagleboard-xM revC with a regular DVI monitor and trying to get the BeagleTouch from LiquidWare to work. I was able to get a basic console image from the older Narcissus and then ‘opkg’ added on packages to get X11 windows environment running. Ethernet works, wireless 802.11 works. However, on the 4.3” LCD display I never see an image.

Possible solutions to make the BeagleTouch LCD screen display an image:

  1. Interrupt u-boot loader and modify the display settings, save to non-volatile memory.

a. OMAP3 # printenv (to see current settings)

b. OMAP3 # setenv dvimode 480x272MR-16@60 (to set the resolution, pixel depth, update rate)

c. OMAP3 # saveenv (to save the settings)

d. Alternatively, OMAP3 # setenv defaultdisplay lcd43 (suggested here but with different opinions here)

  1. Include the settings within a boot.scr script in the boot partition. Contents:

setenv bootargs console=ttyO2, 115200n8 root=/devmmcblk0p2 rw rootfstype=ext3 rootwait
setenv dvimode 480x272MR-16@60
setenv defaultdisplay lcd43 (either one of these display options might work)
fatload mmc 0 0×80300000 uImage
bootm 0×80300000

  1. Directly modify the u-boot source to change the default u-boot settings. (I worked with the u-boot mainline)

a. File /include/configs/omap3_beagle.h, line229

“dvimode=480x272MR-16@60\0” \

“defaultdisplay=lcd43\0” \

Ultimately, none of these solutions worked for me. Regardless of changes #1 and #2, I can see in the u-boot variables at bootup (with printenv) that the default settings were still used, including “defaultdisplay=dvi”, “dvimode=640x480MR-16@60”. Perhaps these didn’t work because the Beagleboard-xM doesn’t have on-board non-volatile memory, and I saw a post somewhere that boot.scr was no longer used for –xM. (is uEnv.txt still necessary? I only have MLO and u-boot.bin on my boot partition because it looks like the kernel uImage is only accessed on /boot/)

Option #3 didn’t work for me because u-boot.bin didn’t load correctly. On the serial terminal, it says “Loading u-boot.bin from mmc” and then nothing. I’m using CodeSourcery Lite 2011.03-41, using arm-non-linux-gnueabi and I’ve actually compiled u-boot, the linux 3.4.1 kernel, and the liquidware kernel and none of them have worked, so perhaps I have a problem with my CodeSourcery installation. But that brings me to one of my other questions.

I put the normal pre-compiled angstrom rootfs on an SD card and it works correctly (X11 booted, display on DVI monitor), but if I swap out /boot/uImage with one of the kernel images I’ve compiled, the kernel crashes after /init/main.c after line890 when it fails to open the serial port at /dev/console (even though those files appear to be in the file system). So do I just have a defective kernel image built, or do you have to make sure to match your kernel revision with a rootfs revision?

Also, rubbing my finger around on the LiquidTouch touchscreen doesn’t cause a mouse movement on the DVI monitor. JKSH noted the kernel source fix for this was committed by LiquidWare on github. I see that those changes weren’t merged into the Linux trunk (3.4.1), though. I’m not sure how to look at the oe/angstrom source to see if it’s been incorporated there.


I just now saw this thread where Gerald Coley said the Liquidware BeagleTouch doesn’t support the Beagleboard-xM.


Any additional details/differences/explanation would be very useful. Comparing the LCD (P11,P13) and Expansion header (P9), the pinouts are the same between BB and BBxM. The only difference which LiquidWare notes is that the connectors need to be removed and soldered onto the top of the board. Ok, I did that. No other hardware changes are required, right?

I also note that there must be different revisions of the BeagleTouch because mine has a large SMT speaker on the back which interferes with the USB connector stacks, whereas the demo video doesn’t have the same component interferences. BTW, has anyone seen schematics for the BeagleTouch and BeagleJuice boards?


That is what I have been told from the Liquidware people. I suggest you as them the What??? question. If you want to adapt it you may be able to. Sounds like you have started that process. Whether it works or not, I can’t say. You need to ask the Liquid folks. As such, I am not aware of any work on the -xM from a SW standpoint where anyone has tried to get it to work. Not really any reason why it shouldn’t.

As to schematics, I have not seen any.