No announcement yet.

uBoot overlay for GEN4-4DCAPE-70T

  • Filter
  • Time
  • Show
Clear All
new posts

  • uBoot overlay for GEN4-4DCAPE-70T

    I'm currently using a GEN4-4DCAPE-70T with a Beaglebone Black running Debian 9.3. In checking the schematic for the GEN4 LCD display it appears that P9.27 is not used. I have an additional CAPE that uses P9.27 for some GPIO. When uBoot runs the two dtbo overlays conflict on the P9.27 pin definition.

    It appears that uBoot is loading BB-BONE-4D7R-01-00A1.dtbo overlay for the GEN4 LCD display. When reverse compiling the BB-BONE-4D7R-01-00A1.dtbo I noticed that the overlay file is reserving P9.27. Why is the overlay file for the GEN4 LCD cape reserving P9.27?

    In the past I've used the 4DCAPE-70T display with Debian version 8 and did not have the conflict with P9.27.

  • #2

    Basically, on the 4DCAPE-70T (old) display, the P9.27 was reserved for the user button.While on the gen4-4DCAPE-70T(new) display,it appears the user button can be optionally used.
    So you will not find on the datasheet (gen4-4DCAPE-70T), that the P9.27 is used. The same overlay is used on both old and new display.

    To avoid the conflict on P9.27, it is helpful to visit and simply modify the available .dts(Device Tree Source) file as found here:

    And, compile it to generate a .dtbo(Device Tree Blob object) file.

    I hope this post will help you and gives you a new idea.

    Warmest regards,