TS.CONF(5)

NAME
ts.conf - Configuration file for tslib, controlling touch screens for embedded devices.

DESCRIPTION

The idea of tslib is to have a core library that provides standardised services, and a set of plugins to manage the conversion and filtering as needed.

The plugins for a particular touchscreen are loaded automatically by the library under the control of a static configuration file, /etc/ts.conf. /etc/ts.conf gives the library basic configuration information. Each line specifies one module, and the parameters for that module. The modules are loaded in order, with the first one processing the touchscreen data first. For example:

      module_raw input
      module variance delta=30
      module dejitter delta=100
      module linear

ENVIRONMENT VARIABLES

Latest versions of the Xorg tslib input driver use hal to configure the touchscreen within Xorg. Environment variables are only needed for the tslib commands.

TSLIB_TSDEVICE
    If the default touchscreen device cannot be found, set the TSLIB_TSDEVICE environment variable to the touchscreen device to use.

    Default: /dev/input/event0

TSLIB_CONSOLEDEVICE
    Tslib default console device.

    Default: /dev/tty

TSLIB_CALIBFILE
    Stores calibration data obtained using ts_calibrate.

    Default: /etc/pointercal

TSLIB_CONFFILE
    Set a different location for the ts.conf configuration file itself.

    Default; /etc/ts.conf.

TSLIB_FBDEVICE
    Framebuffer device to use for the touchscreen support.

    Default: /dev/fb0.

TSLIB_PLUGINDIR
    Plugin directory for tslib.

    Default: /usr/lib/$triplet/ts0/ where triplet is the MultiArch path, e.g. arm-linux-gnueabi.

MODULE PARAMETERS

variance
    Tries to do it's best in order to filter out random noise coming from touchscreen ADCs. This is achieved by limiting the sample movement speed to some value (e.g. the pen is not supposed to move quicker than some threshold).

    This is a greedy filter, e.g. it gives less samples on output than receives on input.

        • delta

        Set the squared distance in touchscreen units between previous and current pen position (e.g. (X2-X1)^2 + (Y2-Y1)^2). This defines the criteria for determining whenever two samples are near or far to each other.

        If the distance between previous and current sample is far, the sample is marked as potential noise. This doesn't mean yet that it will be discarded; if the next reading will be close to it, this will be considered just a regular quick motion event, and it will sneak to the next layer. Also, if the sample after the potential noise is far from both previously discussed samples, this is also considered a quick motion event and the sample sneaks into the output stream.

dejitter
    Removes jitter on the X and Y co-ordinates. This is achieved by applying a weighted smoothing filter. The latest samples have most weight; earlier samples have less weight. This allows one to achieve 1:1 input->output rate.

        • delta

        Squared distance between two samples ((X2-X1)^2 + (Y2-Y1)^2) that defines the quick motion threshold. If the pen moves quick, it is not feasible to smooth pen motion, besides quick motion is not precise anyway; so if quick motion is detected the module just discards the backlog and simply copies input to output.

linear
    Linear scaling module, primarily used for conversion of touch screen co-ordinates to screen co-ordinates.

        • xyswap

        Interchange the X and Y co-ordinates -- no longer used or needed if the new linear calibration utility ts_calibrate is used.

        • pressure_offset

        Offset applied to the pressure value.

        • pressure_mul

        Factor to multiply the pressure value with.

        • pressure_div

        Value to divide the pressure value by.

pthres
    Pressure threshold filter. Given a release is always pressure 0 and a press is always >= 1, this discards samples below / above the specified pressure threshold.

        • pmin

        Minimum pressure value for a sample to be valid.

        • pmax

        Maximum pressure value for a sample to be valid.

debounce
    Simple debounce mechanism that drops input events for the specified time after a touch gesture stopped.

        • drop_threshold

        drop events up to this number of milliseconds after the last release event.

skip
    Skip nhead samples after press and ntail samples before release. This should help if for the device the first or last samples are unreliable.

        • nhead

        Number of events to drop after pressure.

        • ntail

        Number of events to drop before release.

median
    Similar to what the variance filter does, the median filter suppresses spikes in the gesture.

        • depth

        Number of samples to apply the median filter to.

SEE ALSO
ts_calibrate(1), ts_test(1), ts_test_mt(1)