Method for Stabilizing Asynchronous Interfaces
a technology of asynchronous interfaces and interfaces, applied in the field of data transmission, can solve the problems of asynchronous interfaces posing a problem, asynchronous interfaces a problem, and the restriction of the control signal being separate from the data, so as to save valuable wires and reduce latency
Inactive Publication Date: 2008-11-06
INT BUSINESS MASCH CORP
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AI Technical Summary
Benefits of technology
The data transfer interface described in this patent does not require a separate control signal. It uses the data itself to determine if it has changed. The interface also includes stabilization logic to prevent the output data from transitioning through incorrect or illegal states before reaching the new steady-state. Additionally, the interface allows for a programmable delay for the stability window to account for unforeseen skews and noise. The invention also provides system and computer program products corresponding to the described methods. Overall, the invention provides a more efficient and reliable data transfer mechanism.
Problems solved by technology
However, self-calibrating logic can be costly in area.
Asynchronous interfaces pose a problem as well due to extra handshaking signals that often cross between one side of the interface and another.
While prior art techniques solve some of the problems that arise on asynchronous interfaces, there is a restriction that the control signal is separate from the data.
Method used
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[0022]Turning now to the drawings in greater detail, it will be seen that the prior art shown in FIG. 1 contains two circuits that communicate with each other. Shown is a single-direction of the communication. Data bus, 104, is driven by source circuit, 101, and received by sink circuit, 102. There is also a control signal, 103, that is sent from source circuit, 101, to sink circuit, 102. Typically, the data bus, 104, will be allowed to switch and will stabilize on a new value. Then, control signal, 103, will be used to activate a strobe to sample the stable data.
[0023]FIG. 2 shows a more detailed diagram of prior art sink logic, 102. In this embodiment, control signal, 103, and data bus, 104, enter asynchronous receiver circuit, 201. Shown are metastability latches, 202, edge detect circuitry, 203, and staging register or buffer, 204. There are numerous other embodiments for implementing the prior art.
[0024]FIG. 3 depicts the preferred embodiment of a data transfer method utilizing...
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A method and computer system apparatus for asynchronous data transfer between a source and sink without the use of an asynchronous control signal. includes metastability circuits, data change detection logic, a stability window delay counter, and a mux / register pair to allow for the holding of previous stable data during the transition. While the processing logic employed specifically applies to asynchronous logic, the logic can be extended to synchronous or untimed interfaces as well. Also disclosed is a programmable means to adjust the window delay.
Description
RELATED APPLICATIONS[0001]This application is a divisional application based on U.S. Ser. No. 11 / 532,199 filed Sep. 15, 2006 now entitled Apparatus for Stabilizing Asynchronous Interfaces.TRADEMARKS[0002]IBM® is a registered trademark of International Business Machines Corporation, Armonk, N.Y., U.S.A. Other names used herein may be registered trademarks, trademarks or product names of International Business Machines Corporation or other companies.BACKGROUND OF THE INVENTION[0003]1. Field of the Invention[0004]This invention relates to a transfer of data, and particularly to a method of stabilizing one or more bus signals across an asynchronous or untimed interface without the use of a separate control signal for computer system data transfer.[0005]2. Description of Background[0006]In an SMP computer, such as the IBM® z Series® of mainframe computer systems manufactured by IBM, it is vitally important to maintain high levels or performance and interlocking. Many times, there are int...
Claims
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IPC IPC(8): G06F13/372G06F3/00
CPCG06F13/4226
Inventor MEANEY, PATRICK J.CULLEN, ANTHONY P.FEE, MICHAEL
Owner INT BUSINESS MASCH CORP