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Physical Layer Programming (R1)

Physical Layer Programming (R1) - CSCI 232 Computer...

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CSCI 232 - Computer Networking Physical Layer Programming George Blankenship 1 CSCI 232 - Programming George Blankenship 1 CSCI 232 Computer Networking: Physical Layer Programming George Blankenship CSCI 232 - Programming George Blankenship 2 Communication Environment Computer Modem Telephone Telephone circuit Parallel/Serial Interface Physical Layer Interface Link Layer Interface Physical Layer Interface (invisible) CSCI 232 - Programming George Blankenship 3 Lecture Outline Programming concepts – Device control – Device status Win32 API (C++) Javax Comm API
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CSCI 232 - Computer Networking Physical Layer Programming George Blankenship 2 CSCI 232 - Programming George Blankenship 4 Basic Problem Physical layer implemented in hardware – Interface is a computer port – Controls and data use same port Control and data are separated by use of channels Channels are separated by either events or space •Concepts –Channels –Programming •Physical •Win32 API •javax.comm API –Basics –Listeners –Events –Classes –Extensions CSCI 232 - Programming George Blankenship 5 Event Separated Channels In-band signaling Commands and data use same path (wires) Commands reduce user information band pass The current state (command/data) is determined according to information that preceded The keying information cannot be used as data or control information The data pattern that signals “control information follows” is not an available data pattern The information encoding must be the same for control and data •Concepts –Channels –Programming •Physical •Win32 API •javax.comm API –Basics –Listeners –Events –Classes –Extensions CSCI 232 - Programming George Blankenship 6 Space Separated Channels Out-of-band signaling Commands and data use completely different paths (wires, time) No reduction in user information band pass Command path can be used simultaneously with the data path Encoding on the two paths is independent Synchronization of the two paths may be difficult •Concepts –Channels –Programming •Physical •Win32 API •javax.comm API –Basics –Listeners –Events –Classes –Extensions
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