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4DPI 24 HAT monitor back to hdmi problem

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  • 4DPI 24 HAT monitor back to hdmi problem

    hey. just bought me a nice new pi 3.
    i installed latest
    RASPBIAN JESSIE WITH PIXEL and updat\upgrad it from the pi
    then i went to the new documentation and follwed the instarction up to the calibration( didnt do that yet)
    but the screen working fine
    now when i try to go back to the hdmi display with the
    startx -- -layout HDMI
    i get this:

    X.Org X Server 1.18.4
    Release Date: 2016-07-19
    X Protocol Version 11, Revision 0
    Build Operating System: Linux 4.4.26-v7+ armv7l Raspbian
    Current Operating System: Linux raspberrypi 4.4.34-v7+ #1 SMP Thu Dec 29 11:16:26 UTC 2016 armv7l
    Kernel command line: 8250.nr_uarts=0 dma.dmachans=0x7f35 bcm2708_fb.fbwidth=1920 bcm2708_fb.fbheight=1200 bcm2709.boardrev=0xa02082 bcm2709.serial=0x4286c5e1 smsc95xx.macaddr=B8:27:EB:86:C5:E1 bcm2708_fb.fbswap=1 bcm2709.uart_clock=48000000 vc_mem.mem_base=0x3dc00000 vc_mem.mem_size=0x3f000000 dwc_otg.lpm_enable=0 console=ttyS0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait quiet splash plymouth.ignore-serial-consoles
    Build Date: 11 November 2016 11:59:59AM
    xorg-server 2:1.18.4-2+rpi1 (
    Current version of pixman: 0.33.3
    Before reporting problems, check
    to make sure that you have the latest version.
    Markers: (--) probed, (**) from config file, (==) default setting,
    (++) from command line, (!!) notice, (II) informational,
    (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
    (==) Log file: "/home/pi/.local/share/xorg/Xorg.1.log", Time: Mon Feb 6 19:43:27 2017
    (==) Using system config directory "/usr/share/X11/xorg.conf.d"
    Fatal server error:
    (EE) parse_vt_settings: Cannot open /dev/tty0 (Permission denied)
    Please consult the The X.Org Foundation support
    for help.
    (EE) Please also check the log file at "/home/pi/.local/share/xorg/Xorg.1.log" for additional information.
    (EE) Server terminated with error (1). Closing log file.
    xinit: giving up
    xinit: unable to connect to X server: Connection refused
    xinit: server error
    Couldn't get a file descriptor referring to the console
    im new to the pi
    so maybe im doing something wrong but i just followed the instructions on the Document Revision: 1.8
    thanks tal.

  • #2
    Dear Tal katz

    You can switch from 4D LCD to HDMI by using the command:

    sudo startx -- -layout HDMI

    However, you will get an error saying GDBusError.freedesktop.Policykit1.Error.Failed

    One way to remove it is to use this command

    sudo lxsession-edit

    uncheck the LXPolkit option

    if No LXPolkit Option:

    1. open Terminal
    2. type sudo leafpad /etc/xdg/autostart/lxpolkit.desktop
    3. Add the text LXDE to the line NotShownIn
    4. The line should read:
    5. Save and sudo reboot

    Best regards,


    • #3
      thanks for the quick replay
      i tried several times to do the above but
      sudo startx -- -layout HDMI not working and
      no such file on the directory you told me
      when typing this type sudo leafpad /etc/xdg/autostart/lxpolkit.desktop i only get new file every time.

      Click image for larger version  Name:	Capture.JPG Views:	1 Size:	44.2 KB ID:	55980

      i found the line NotShownIn on the lxkeymap file and added the LXDE
      and now the switching is happening but i get this error after screen changes
      Click image for larger version  Name:	Capture.JPG Views:	1 Size:	32.4 KB ID:	55981
      and after few min the pi froze and i had to restart it and then i got the login with password screen
      typing the def password for pi and it say incorrect( happened to me more then one time i tried to install the screen)

      Last edited by Tal katz; 12 February 2017, 06:56 PM.


      • #4
        Dear Tal Katz,

        Please see this forum post. The customer has no problem using sudo startx -- -layout HDMI. In particular, please see post number 4 and 6.


        • #5
          Dear Noel
          i watched the post you linked
          both 4 and 6 are almost 1 year old and both of them talking about 4d-hats_4-1-10_v1.0 while i use the 4d-hatss_4-4-34_v1.1
          also im using RASPBIAN JESSIE WITH PIXEL that was intredust on Sep 2016( 4 and 6 are form March 2016)

          i tested it 10 times the past day. i do clean install follow your instruction and every thing is good until first time im using the "sudo startx -- -layout HDMI"
          after boot or jumping few times from TFT to HDMI and back the pi go to login screen which was not default and don't accept the default password for user pi (raspberry),
          if there is no solotion for my problem ill just try to return the screen to the store i bought it from.
          thanks tal


          • #6
            Dear Tal katz,

            Please see this forum link. Here is one solution to your problem:


            Best regards,


            • #7
              Hi guys.

              Just got 4DPI-24-HAT from element14. I followed the installation instructions from your web site:
              but still unable to get it working - the screen stays black and input goes to HDMI after reboot. Please help


              • #8

                Welcome to the forum,

                Can you please check the jumper on the rear of the PI-HAT and if it is on PWM please change it to ON/OFF

                Best regards



                • #9
                  Originally posted by pauleilio View Post

                  Welcome to the forum,

                  Can you please check the jumper on the rear of the PI-HAT and if it is on PWM please change it to ON/OFF

                  Best regards

                  Hi Paul,
                  Tried with jumper set to On/Off - screen is still black.


                  • #10
                    Hi gogoffer,

                    Please follow the steps below for your 4DPi-24-HAT.
                    Make your micro SD card ready. Format it to its original size to start a fresh new image.

                    1. Download the latest raspbian image from the Raspberry Pi Website:

                    The new Raspbian image as of today: 2017-09-07-raspbian-stretch
                    Choose the the file: 2017-09-07-raspbian-stretch

                    2. Load the Raspberry Pi image onto a SD card, using the instructions provided on the Raspberry Pi website for Linux, Mac or PC:

                    3. Insert the SD card into the Raspberry Pi. Do not connect the 4DPI-24-HAT yet. You will need an external monitor / keyboard / network connection. Apply power to start. The Raspberry Pi automatically expand the file system (on first start).

                    4. The Raspberry Pi will boot directly to the Desktop Environment. You need to edit some raspberry pi configuration. You can do it via Desktop GUI or via Terminal.

                    5. First, to use Desktop method. Click to the raspberry icon, go to preferences and select the Raspberry Pi configuration. Go to Interface tab, search for SSH and tick Enable. On using the terminal, Open the Terminal, type $ sudo raspi-config to open the Raspberry Pi Software configuration tool. Select Interfacing Options, select SSH, select Yes to enable. Then OK, go to finish and reboot the system.

                    6. Once rebooted, log into your Raspberry Pi again, you can now also acces your raspberry pi using SSH. You will need to download and install the kernel which supports the 4DPI-24-HAT. The following step requires sudo ‘root’ access.

                    7. Download and install files, enter the following commands in terminal/shell /SSH to download the kernel from the 4D Systems Server:

                    On the Terminal/SSH type:

                    when download complete. Type:

                    sudo tar -xzvf 4d-hats_4-9-35_v1.0.tar.gz -C /

                    The package automatically selects the kernel required for Pi1, Pi2 or Pi3 automatically, unlike previous versions. No manual editing of confix.txt is required.

                    8. Shutdown the Raspberry Pi safely, and remove the power after it has completed its shutdown. For shutting down use the following command

                    On Terminal, Type:
                    sudo poweroff
                    sudo halt

                    11. Connect the 4DPI-24-HAT to the Raspberry Pi, and reapply power. The terminal should begin to show on the 4DPI-24-HAT, and will be ready to use once the Raspberry Pi has booted.

                    Do not update your raspberry pi after you successfully installed the 4Dpi kernel, because it my change some configuration of your 4DPI-24-HAT. We will keep you updated if a new 4DPI kernel is available for your device.

                    Hope this help,

                    Best Regards,


                    • #11
                      Hi frsantiago

                      I have the same problem as gogoffer.
                      I followed the instructions in the data sheet ...
                      sudo tar -xzvf 4d-hats_4-4-21_v1.0.tar.gz -C /
                      sudo raspi-config (set to boot to CLI logged in as 'pi')
                      sudo poweroff

                      Then I mounted the display (with PWM jumper in the OFF position) on my RPi3 (with Raspbian Stretch installed)

                      But when I restart, the display is always blank

                      I connected the HDMI, and can see it go through the initial boot steps as far as the "Shift for Recovery" screen, then it also goes blank.

                      The green LED shows no activity

                      I tried to connect by PuTTY, but no response.

                      How can I recover my files from the SD card?
                      Is my only option to wipe everything?
                      Is there a way to undo?



                      • #12
                        Hi domr001,

                        Good day.

                        Welcome to the forum.

                        If you can’t connect with your raspberry pi with putty then the only way is to wipe everything and start a new installation.
                        Follow the instruction on the datasheet, but on step 8, download our latest kernel release

                        $ wget

                        Then install,

                        $ sudo tar –xzvf gen4-hats_4-9-59_v1.2.tar.gz –C /

                        When the installation is done. Power off your raspberry pi and put the 4DPi-24-Hat.

                        Apply power.



                        • #13
                          Hi frsantiago,

                          Originally posted by frsantiago View Post
                          If you can’t connect with your raspberry pi with putty then the only way is to wipe everything and start a new installation.
                          Yes - I was afraid that you might say that.

                          However, I did manage to salvage my files...
                          I put the memory card into a USB memory card reader, and plugged it into another RPi.
                          Then I was able to access the media and extract what I needed (phew)

                          Thanks again


                          • #14
                            In recent releases of Raspbian, in order to make Putty etc talk to the Pi over SSH, you need to enable SSH. Either from raspi-config or by putting the SD card into your computer, and adding a file called 'ssh' without the quotes, onto the dos partition. just 'ssh', no extension, no contents, just a blank file. Put it back in your Pi and the Pi should then have SSH enabled for you to remote into it.