Configuration parameters for filter

ballistic

Minimizes the noise normally seen on successive touch events that follow a low-speed ballistic trajectory. The lower the speed of the ballistic movement (e.g., a stationary finger), the more gain reduction is applied to the speed of the movement. By doing so, the result is a solid touch with no noise.

edge-swipe

Detects the passing of a finger over the edge of the touch surface. This lets you get swipe gestures starting from outside the screen.

kalman

Minimizes the tracking noise of a moving finger on a given touch surface by use of the Kalman filter algorithm.

bezel-touch

doa

Filter specific options. The available filter options depend on the filter type. The format for configuring filter options is: options= <filter option>=<value> or, if there are multiple options to specify, then each option-value pair will be separated by a comma: options= <filter option1>=<value>,<filter option2>=<value>

Options are listed below per filter type:

• ballistic

  Filter option	Description	Default
  scale	FP scale factor	256
  min_gain	Minimal gain	8
  low_speed	Low speed threshold	32

• edge_swipe_detect

  Table 1. Filter order

  Filter option	Description	Default
  filter_order	Filter Order	2

  Table 2. Left edge (x=0)

  Filter option	Description	Default
  xl_enable	Apply detection	1
  xl_bezel	Bezel width	50
  xl_speed	Speed threshold	25
  xl_jitter	Jitter control	0
  xl_reject_physical_bezel	Reject physical bezel	0

  Table 3. Right edge (x=max(raw_x))

  Filter option	Description	Default
  xh_enable	Apply detection	1
  xh_bezel	Bezel width	50
  xh_speed	Speed threshold	25
  xh_jitter	Jitter control	0
  xh_reject_physical_bezel	Reject physical bezel	0

  Table 4. Top edge (y=0)

  Filter option	Description	Default
  yl_enable	Apply detection	1
  yl_bezel	Bezel width	80
  yl_speed	Speed threshold	25
  yl_jitter	Jitter control	0
  yl_reject_physical_bezel	Reject physical bezel	0

  Table 5. Bottom edge (y=max(raw_y))

  Filter option	Description	Default
  yh_enable	Apply detection	1
  yh_bezel	Bezel width	50
  yh_speed	Speed threshold	25
  yh_jitter	Jitter control	0
  yh_reject_physical_bezel	Reject physical bezel	0

  Note: edge-swipe filter options nomenclature:

  • xl: x-low border, near x=0;
  • xh: x-high border, near x=maximal X touch coordinate;
  • yl: y-low border, near y=0;
  • yh: y-high border, near y=maximal Y touch coordinate;
• kalman

  Table 6. Noise variance

  Filter option	Description	Default
  proc_noise_x_var	Process noise variance (X)	32
  proc_noise_y_var	Process noise variance (Y)	32
  meas_noise_x_var	Measurement noise variance(X)	100
  meas_noise_y_var	Measurement noise variance (Y)	100

  Table 7. Adaptive speed threshnold

  Filter option	Description	Default
  slot_threshold_1	Adaptive speed threshold 1	30
  slot_threshold_2	Adaptive speed threshold 2	20
  slot_threshold_3	Adaptive speed threshold 3	10
  slot_threshold_4	Adaptive speed threshold 4	5

• bezel_touch

  Filter option	Description	Default
  parrallel_threshold	Filter parallel threshold	140
  perpendicular_threshold	Filter perpendicular threshold	70