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    • Resistive Touch, Trizeps VIII

    Owned by Albinleo Velappan (Deactivated)
    Last updated: 06. Oct 2022
    3 min read

    The Kinetis MCU default firmware of the Trizeps VIII (Mini) includes a code to act as a touch controller.

    Config

    TOUCHSCREEN_KUK_TR8MCU

    Source

    /linux_imx/drivers/input/touchscreen/kuk_tr8mcu_touch.c

    How to modify Settings

    $ cd /sys/bus/i2c/devices/2-0010 /sys/bus/i2c/devices/2-0010$ ls average modalias power swapxy x xraw ymax yscale driver name settle threshold xmax xscale ymin zraw input of_node subsystem uevent xmin y yraw

    Get a setting or touch value; ie. get the last measured raw x value:

    /sys/bus/i2c/devices/2-0010$ cat xraw 41

    Change a setting; ie. swap x and y axis and invert the x-axis:

    /sys/bus/i2c/devices/2-0010$ echo 3 > swapxy

    Value

    I2C-Register

    Description

    Value

    I2C-Register

    Description

    xscale

    TOUCH_XSCALE_LSB/MSB

    The max. value „xraw“ is scaled „x“ to. Typ.: screen-width

    yscale

    TOUCH_YSCALE_LSB/MSB

    The max. value „yraw“ is scaled „y“ to. Typ.: screen-height

    xmin

    TOUCH_XMIN_LSB/MSB

    xraw value, when left edge of screen is touched

    xmax

    TOUCH_XMAX_LSB/MSB

    xraw value, when right edge of screen is touched

    ymin

    TOUCH_YMIN_LSB/MSB

    yraw value, when top edge of screen is touched

    ymax

    TOUCH_YMAX_LSB/MSB

    yraw value, when bottom edge of screen is touched

    threshold

    TOUCH_CONFIG

    Defines trigger level at which a touch-press is detected 0..63

    settle

    TOUCH_WAITTIME

    Time in ms to wait between before measurements

    average

    TOUCH_AVERAGE

    Number of samples to average for each point

    swapxy

    -

    0x0: no change, 0x1: swap x and y axis, 0x2: invert x-axis, 0x4: Invert y-axis

    x

    TOUCH_XSCALE_LSB/MSB

    scaled x value of last measurement (Bitmask 0x8000: no touch press)

    y

    TOUCH_YSCALE_LSB/MSB

    scaled y value of last measurement (Bitmask 0x8000: no touch press)

    xraw

    TOUCH_XMIN_LSB/MSB

    last raw x value

    yraw

    TOUCH_YMIN_LSB/MSB

    last raw y value

    zraw

    TOUCH_XMAX_Z_LSB/MSB

    last raw z value. Z-measurement must be enabled

    Device-Tree for resistive Touch-Controller

    Example:

    For a description of the settings see table above.
    The swapxy is split into 3 values for the device-tree:

    swapxy

    Swap x and y axis

    xreserve

    Invert x axis

    yreserve

    Invert y axis