Specifications

82 Chapter 6 - Command Reference
Filter ('F','f')
Function: Used to control various aspects of the firmware filtering algorithms
used in the controller.
0 1 2 3 4 5 6 7
Query: 'f'
Set or 0 1 2 3 4 5 6 7
Response: 'F' Type SLen Width States Control
The Type byte indicates the touchscreen type selected by the jumpers on the
controller as follows: an ASCII '0' for AccuTouch, '1' for DuraTouch, and '2' for
IntelliTouch. The Type field cannot be changed.
The SLen byte specifies the number of coordinate samples (1-255) to average
before reporting the results. The factory default value is 4.
The Width byte specifies the allowable deviation (±1-255) in validating a touch
coordinate measurement. All touches within an averaging cycle (number specified
by SLen) must be within this specified window or the coordinate is discarded. The
factory default value is 32 for the E271-2210 controller and 8 for all other
controllers.
The States byte specifies the number (1-255) of valid touch detections (or
untouch detections) to signify a change in the state of the touch event. For
example, a value of 8 sets the state detection function to require that 8 contiguous
touch measurements be made to cause the controller to process an initial touch.
Similarly, 8 contiguous untouches must be measured to cause the controller to end
the touch event. The factory default is 8.
The Control byte comprises two 4-bit numeric values:
The high order 4 bits specify a touch-down detection threshold (0-15), related to
voltage. A value which is too low can cause the controller to report erroneous
untouch coordinates. A value too high may prevent valid touches from being
recognized. The factory default value is 9.
The low order 4 bits specify the number of additional 0.5ms delays to use when
changing the drive signals to the touchscreen (0-15). A value of 0 specifies a delay
of 0.5ms, with each increment specifying an additional 0.5ms delay. The factory
default value is 1 for the E271-2210 controller and 0 for all other controllers.