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GEN4 4D Cape 50CT CLB, BBB , touch does not work with activated SPI

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  • GEN4 4D Cape 50CT CLB, BBB , touch does not work with activated SPI

    Hello @all,

    my System:
    Beaglebone Black,
    Debian 9.5 iot, 2018-10-07
    Kernel 4.14.94-ti-r91

    GEN4 - 4DCAPE-50CT-CLB

    If I activate SPI in the file uEnv.txt the touch function of the display does not work anymore.
    Everything is displayed correctly.
    I can also move the cursor with a mouse.
    But the touchpad doesn't work anymore. What could be the reason ?
    The touchpad is connected via I2C.
    I don't understand where the conflict can arise.
    The cape was recognized nevertheless properly.

    A part of my uEnv.txt
    ###Additional custom capes

    If i deactivate SPI
    The touchpad works fine.
    But then I don't have access to my DAC via SPI.

    Can someone help me?
    Thank you

  • #2

    Thank you for posting your problem here.

    The reason is there is a conflict between the touch controller IC and SP0's assigned pin when activating the SP0 because the SCK of the touch controller IC is connected to the pin17 of the BBB P9 header, which is the default chip select pin of the SP0 as shown below.

    Click image for larger version  Name:	final.JPG Views:	0 Size:	183.4 KB ID:	68138

    Consequently, you could use SP1 (BBB's second SPI) by utilizing the BB-SPIDEV1-00A0.dtbo.
    Please let me know if it works.

    Best regards,


    • #3
      Thank you very much for this Info.
      That makes sense.
      I will test it as soon as possible.
      But it will take a few more days.

      Have a nice day