Grayhill Multi-Touch Control Wheel - Software Development Kit V3.0 - Manual (Page 13)

Multi-Touch Ring Encoder Software Development Kit User’s Guide v3.0
© 2014 Grayhill, Inc., Confidential and Proprietary Page 13
For the discussion of the components of the MTCW see the block diagram of
the MTCW shown below:
USB – I/O Interface
The MTCW has a full speed USB device interface. Data that is transmitted
from the MTCW to the host includes the following: the raw touch positions,
proximity status, encoder (outer ring) changes, and pushbutton status. Data
can be sent to the MTCW to set the current touchpad/proximity mode, or
change the backlight or highlight on - off or control the brightness.
In addition to the USB connector, a redundant output is provided that
contains the quadrature output I/O from the encoder and the pushbutton
status.
Touchpad
The touchpad built into the MTCW 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 MTCW, 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.
Multi-Touch Control Wheel
Touchscreen
Touchscreen
Controller Proximity
Sensor
Switching
Power Supply
Micro-controller
Power
USB