Boot with LVDS display; Save application on development board

Dear Developer,

I request support regarding the transfer of the QT application to the Apalis Evaluation Board with imx8 processor and the b2qt module.

  1. We are unable to view via the LVDS connector (the display is powered but nothing is displayed, jumpers x40 and x39 are set to LVDS)

  2. How do you store the created qt application on the card?

Thanking in advance


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Hello Gaetano,

For your concerns regarding the use of an LVDS display and deploying a Qt application on the Apalis Evaluation Board with an iMX8 processor, here are some steps and considerations:

  1. LVDS Display Not Showing Content:

    • Ensure your device tree settings are correctly configured for LVDS output. The iMX8 processor requires specific device tree configurations to enable LVDS output. You might need to adjust the device tree to match your display’s specifications, including resolution, timing, and interface details.
    • Verify that the display’s specifications are compatible with the iMX8’s LVDS output capabilities. This includes checking voltage levels and signal formats.
    • Double-check the physical connections, ensuring that the LVDS cables are securely connected and that the display power supply meets the required specifications.
    • If you are using a custom Linux image or a pre-built image from Toradex, ensure that the display drivers are included and properly configured in the kernel.
  2. Storing and Running a Qt Application:

    • To deploy a Qt application to the Apalis board, you can use several methods, including SCP (Secure Copy Protocol), NFS (Network File System), or a USB drive. The choice depends on your development and deployment workflow.
    • For development purposes, running the application directly from a development PC over the network (using NFS) or by copying the application binary using SCP can be convenient. This allows for rapid iteration without needing to store the application on the device permanently.
    • For production or more permanent deployment, you can include your Qt application within a custom Yocto image. This involves creating a Yocto recipe for your application, which then becomes part of the image build process. The application gets installed into the image, and you can configure the system to auto-start your application on boot.
    • Another approach is to manually copy your application to the device’s storage (e.g., internal flash or an SD card) and set up an init script or systemd service to start your application automatically upon boot.

Remember, when deploying your application, consider the dependencies it might have, such as Qt libraries or other system libraries, and ensure they are also available on the target system.

For device tree adjustments, refer to the iMX8 and Apalis documentation for the specific nodes and properties related to LVDS configuration. For Yocto, the Toradex documentation provides extensive guides on creating custom images and recipes.

Best regards,
Toradex AI Assistant

Please, also check if these links can help you solve your problem:

First Steps with Capacitive Touch Display 10.1 Inch LVDS | Toradex Developer Center.


Concerning your first issue I believe you issued this question here before. Were you able to try out my suggestions? :slight_smile:

There are generally three ways to run the Qt framework on Toradex modules:

Please let me know how you fare on these two subjects

Best regards