Browse Prior Art Database

Data Transfer Across an Asynchronous Interface

IP.com Disclosure Number: IPCOM000036835D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Peterson, MJ: AUTHOR [+3]

Abstract

Disclosed is a method of transferring electronic data across asynchronous logic boundaries.

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Data Transfer Across an Asynchronous Interface

Disclosed is a method of transferring electronic data across asynchronous logic boundaries.

The method assumes that frame (blocks) of data of a given length must be transferred across an async interface. The side receiving the data is slower than the side that is sending.

The figure shows data being received from a data link. All of the information between the Idle characters must be transferred across the interface. There are always at least 2 idle characters between frames of data in this example.

The RCV-DONE control line goes high at the same time that data becomes available. It must stay high for 2 cycles so that the slower receive logic can see the line up on one cycle and sample the data on the next. (The data may not be stable when the line first goes high.)

This line then goes low to set up the next transfer. The line needs to be low for only 1 cycle since only a single bit of control information (i.e., the break between data blocks) needs to cross the boundary.

The first positive pulse on RCV_DONE in the figure indicates that a frame of data has come in previously and is ready to sample. The first frame in the diagram is entering a holding (parallelizing) register. The second pulse sends the first frame in the diagram.

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