9 Replies Latest reply on Oct 7, 2014 6:31 PM by septimo

    BB-VIEW 7" touchscreen display blank


      I seem to be having difficulty getting a just purchased BeagleBone Black and BB 7" Touchscreen display to work. I wonder if someone could give some help.


      Followed the hardware installation instructions in the manual, which are easy enough. After fiddling around with Debian, in which I could get HDMI OK and all else seemed to work fine, Went looking for the TI Angstrom demo. After working through the Element14 links I dug BBB-eMMC-flasher-2013.09.04.img out from BeagleBoard.org - latest-images. I am still presented with a blank screen.  Is this the correct image?


      It shows the cape not being recognised.

      # more /sys/devices/bone_capemgr.*/slots

      0: 54:PF---

      1: 55:PF---

      2: 56:PF---

      3: 57:PF---

      4: ff:P-O-L Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G

      5: ff:P-O-L Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI


      Followed instructions in the BB-View Cape user manual with  no effect (the images suggested are actually a later date than the latest images from beagleboard.org, but cannot find them on Element14's site).


      Back to Debian. After updating the kernel as suggested in the Debian Howto, and setting in uEnv.txt:

      optargs=capemgr.disable_partno=BB-BONELT-HDMI,BB-BONELT-HDMIN capemgr.enable_partno=BB-VIEW-LCD7-01


      got the same result - cape not recognised, similar to here BB View + BeagleBone Board.


      That seems to be the end of my competence. Any suggestions?

        • Re: BB-VIEW 7" touchscreen display blank

          Just a thought - I wonder if there would be an entry in /sys/devices/bone_capemgr.*/slots? Files in that directory seem to have information from the devices which presumably comes from an EEPROM, of which the BB-View has none.

          • Re: BB-VIEW 7" touchscreen display blank

            Back to the start to try to make some sense out of this.


            Put the Angstrom distro BBB-eMMC-flasher-2013.09.04.img.xz from BeagleBoard.org - latest-images onto a microsd card and flashed to eMMC. After several tries got it to boot up OK.


            The web page element14: BB View LCD Cape Software Download Centre[1] contains images that are patched for the BB-VIEW, but on opening they appear to be compiled kernel. Unfortunately there is no documentation provided to explain how to use these, I'm not a Linux kernel hacker so I googled around to get some ideas. What i ended up doing was to take the Angstrom image, modify xorg.conf with 50-tslib.conf and scp'd it all across. Then


            # opkg install xf86-input-tslib_0.0.6-r17.1_armv7a-vfp-neon.ipk

            # cp -f uImage /boot

            # cp -f *.dtb /boot

            # tar -xvf kernel_modules.gz -C /

            # cp -f xorg.conf /etc/X11/

            # sync



            The BBB booted up OK but nothing on the BB-VIEW screen. Screen lights up but shows no output.


            Still hoping someone might come to the rescue :-)


            EDIT I'm really not with it this week. It's described in the manual and requires a dtb file to be renamed to recognise the 7" display. Sorry everyone. Angstrom came up on the screen to a command-line login, but no desktop. Didn't pursue it further.

            • Re: BB-VIEW 7" touchscreen display blank

              Put the Debian distro BBB-eMMC-flasher-debian-7.5-2014-05-14-2gb.img.xz from BeagleBoard.org - latest-images onto a microsd card and flashed to eMMC.


              Grabbed the patched kernel file BB VIEW Debian Image.zip from element14: BB View LCD Cape Software Download Centre[1], unzipped and scp'd across. Installed with:


              # cp xorg.conf /etc/X11/

              # cp *.dtb /boot/uboot/dtbs/

              # cp zImage /boot/uboot/

              # tar -xvf kernel_modules.tar.gz -C /

              # sync


              ssh into the BBB, root has no password. Edit the /boot/uboot/uEnv.txt file as follows:





              Works a charm.


              PS when plugging the LCD to the cape, make sure that the FPC cable has the exposed metal facing down and the blue stripe facing up. Don't follow the pictures showing the writing facing up as I did (followed by 3 days of frustration).


              Also the TI demo image from element14: BB View LCD Cape Software Download Centre[1] works fine once the uEnv.txt file has been updated according to the manual.


              EDIT: Seeing this has evolved from a question to something else, I'll report that eventually having experienced so many difficulties with touchscreen not working properly that I went back to follow the post [How-to] BB-View on latest Debian to compile the kernel, and loaded up all the tar files in the deploy directory as well as zImage. This worked OK with the exception that the fix for switching red-blue caused the boot process to hang, but I can live with different colours.

                • Re: BB-VIEW 7" touchscreen display blank


                  Great article which saved me a bunch of time.

                  I followed every step above and once I reversed the ribbon cable I get the backlight on the BB View.

                  However there is nothing displayed on the LCD screen.

                  Should I see something on the screen?

                  I can still use the BBB view USB cable and SCP to it so I know the unit is working.


                  Not sure where to go from here.

                    • Re: BB-VIEW 7" touchscreen display blank

                      Yes you should see a desktop. Possibly the easiest route, if you haven't done so, would be to flash the TI SDK demo that has been patched for the BB-VIEW as that is a full working image and requires only one small change as outlined in the"BB-View Cape User manual" (page 21)


                      # echo "optargs=dispmode=7inch_LCD" > /media/mmcblk0p1/uEnv.txt

                      # sync


                      (uEnv.txt should appear in /boot). Once that's going you can have confidence that the display is working. I'm not sure how to advise after that. If you are working with the Angstrom kernel then I think there is still a step missing as I also got a blank screen (actually it went white then gradually faded to a darker shade). EDIT the final step is given in the bb-view user manual.. Anyway Debian is the one that works for me.


                      Note that after I got the TI Demo and then Debian working, I went back over the process to make sure that I had included all the steps for this writeup, but found the BBB flashing process was very unreliable. I had to rewrite the SD card and go through the procedure several times before I got the thing working again (although WICD still isn't working properly). It was failing to boot up after changing the kernel. So I'm not really keen to try investigating this further in case I can't get the beast going.

                        • Re: BB-VIEW 7" touchscreen display blank

                          I've narrowed it down.

                          I flashed the Black back to the latest Debian Image and rebooted when the 4 lights came up solid.

                          It then sat there and came up with the "this is a temporary session eMMC flash in progress" and used 100% CPU for several minutes.

                          Then it powered down.

                          After the next reboot it came up OK with latest Debian.

                          I scp the BB View files over to the BBB


                          I ran terminal and executed the cp etc. commands (adding sudo before each) to copy the kernel files.

                          I did not make the changes to the uEnv.txt as I wanted to make sure that the BB booted up with the new kernel.

                          I then rebooted and the BB starts but displays nothing on the HDMI screen or the LCD screen.

                          Heartbeat is there and processor light is flashing continuously but I can no longer scp to it - looks like it's in a loop.


                          Any suggestions gratefully received - I will also try the TI SDK one tomorrow.

                            • Re: BB-VIEW 7" touchscreen display blank

                              That's more or less what I was seeing a few times except that there was some text on the LCD screen, but if you haven't changes uEnv.txt then it will probably not use the LCD (though it should have used HDMI). I had to reprogram the SD card first, then reflash the BBB a few times before it worked.

                              1 of 1 people found this helpful
                      • Re: BB-VIEW 7" touchscreen display blank

                        Hi, excellent instructions and I appreciate it very much. I do have a question though. My BB works well with the Ti SDK image so I know the hardware works. My confusion, and before I try it, is the SCP part of the process you describe. Where do you SCP to? Would it be possible to provide a sample of the command? I presume you are SCPing to the root in the BB but I want to be sure.


                        thanks in advance