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Once the WiFly unit is setup it can be taken out of command mode. Any further system
changes can be made via a TCP/IP telnet session, given that the user knows the IP
address of the WiFly unit [9].
In command mode there are many options the user can configure to suit the project's
needs. There are options to use User Datagram Protocol (UDP) or TCP/IP protocols.
There are data transfer rates that can be changed, along with buffer size and packet
terminator characters to make custom size packets. There are a lot of useful features
that make this device an easy solution to embedded wireless networking.
The WiFly unit has external pins for sensor implementation. This is useful when the
designer wants to have the WiFly unit broadcast data upon a sensor trigger
sequence. The external pins can also be used to initiate sleep or to wake the module.
Automatic commands can also be configured such as configuring the WiFly unit to
obtain an IP address upon power up. Another example could be the automatic
writing of bytes to the UART connection when a task is completed or a sensor has
been triggered.
4.4 Capacitive Touch
Capacitive touch sensing technology works on the concept that a change in the
capacity of a button type interface results in a change of a signal that is being
monitored. The button type interfaces can range from simple buttons and slide bars to
large touch screens that track the location of where the user’s finger is on the surface.
All of these examples use the same method of detection. When the capacitance change
alters the signal, the change in the signal is recognized by the system and can then be
used to trigger specific actions in the system.
The skin of the finger acts partially as a dielectric and partially as a conductor which
interacts with surrounding electric fields. The electrolytes within the fingers also
interact with the electric fields. As the finger touches the area of the capacitive touch
sensor, this interaction with the electric fields is what changes the capacitance. The
finger and the body physically become part of the capacitance of the system, adding to
the existing capacitance of the circuit. This change in capacitance then modifies the
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