Grayhill Multi-Touch Ring Encoder - Software Development Kit V3.0 - Manual (Page 14)

Multi-Touch Ring Encoder Software Development Kit User’s Guide v3.0
© 2014 Grayhill, Inc., Confidential and Proprietary Page 14
Touchpad
The touchpad built into the MTRE uses the mutual projected capacitive
method to track up to 5 touch positions simultaneously with a 20mS sample
rate. Some features of the touchpad are listed below:
• As each individual touch is sensed, the touch is assigned the lowest
number available from 0 to 4 for reporting.
• The touch is tracked under this number until it has been released.
• The screen has an overall resolution of 1280 x 1280, although because
of the round shape, not all of these positions are utilized.
• No gesture recognition is provided in the MTRE, but “Instinct” -
Grayhill’s gesture recognition library, is available to our customers and
will be introduced later in this guide.
• Two-touch differentiation can be sensed down to about 3mm.
• Touch sensing will work with latex gloves.
• The MTRE can be set to either Touch or Proximity mode, but they
cannot be used simultaneously.
Ring Encoder
An encoder is connected to the outer ring, which in turn drives the I/O
outputs and also is connected to the internal controller for assembly into
USB packets. The encoder provides relative (not absolute) position of the
outer ring. The USB packet contains the number of counts (up or down)
since the last time the MTRE was polled (20ms sample rate.) The I/O
connector provides the output directly from the encoder in quadrature format
as shown below:
The ring encoder is available in 32 or 48 positions with 3 different torque
options. The ring encoder functions in either the touch or proximity mode.
Pushbutton
The pushbutton make and break information is available on the USB and as
a redundant I/O. The I/O is “low” whenever the pushbutton is active and