Circuit with switch controller that signals switch control input to close switch upon completing request acknowledgment of connection request from data transfer port
First Claim
1. Electrical circuitry, comprising:
- a data transfer port;
a switch to make selectively a desired connection within said electrical circuitry, said switch having a control input to control opening and closing thereof; and
a switch controller coupled to said port and having an output which, in response to a connection request received at said port, applies a request acknowledgement to said port, said switch controller having a further output which is connected to said control input of said switch and which, in response to completion of said request acknowledgement, signals said control input to close said switch.
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Abstract
A protocol and associated circuitry operable for efficiently extending serial bus capability in system environments is disclosed. The protocol is designed to coexist and be fully compatible with existing serial bus approaches, and in particular an example of application of the invention to a backplane system utilizing the 1149.1 IEEE standard serial bus is detailed. The circuitry and protocol required to couple any one of the boards on the backplane to the serial bus master without modifying the existing serial bus protocol, without adding additional signals, and without affecting the throughput rate of the serial bus is described. The invention advantageously allows the serial bus master to select, communicate with, and deselect backplane boards so that high level test functions may be simultaneously executed and monitored. Additional preferred embodiments are also disclosed.
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Citations
7 Claims
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1. Electrical circuitry, comprising:
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a data transfer port; a switch to make selectively a desired connection within said electrical circuitry, said switch having a control input to control opening and closing thereof; and a switch controller coupled to said port and having an output which, in response to a connection request received at said port, applies a request acknowledgement to said port, said switch controller having a further output which is connected to said control input of said switch and which, in response to completion of said request acknowledgement, signals said control input to close said switch.
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2. Electrical circuitry, comprising:
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first and second data transfer ports; a switch connected between said first and second ports, said switch having a control input to control opening and closing thereof; and a switch controller coupled to said first port and having an output which, in response to a connection request received at said first port, applies a request acknowledgement to said first port, said switch controller having a further output which is connected to said control input of said switch and which, in response to completion of said request acknowledgement, signals said control input to close said switch.
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3. A method of closing a switch, comprising the steps of:
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issuing a request to close the switch; issuing a request acknowledgement in response to the request; and closing the switch in response to completion of the request acknowledgement.
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4. Electrical circuitry, comprising:
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first and second data transfer ports connectable to one another and cooperable when connected to communicate therebetween according to a first communication protocol; and acknowledgement circuitry coupled to said first port, said acknowledgement circuitry having an output which, in response to communication at said first port according to a second communication protocol, applies to said first port an acknowledge signal.
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5. A method of operating data transfer ports, comprising the steps of:
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applying to one of the ports a request according to a first communication protocol; applying an acknowledgment signal to said one port in response to the request; and communicating between the ports according to a second communication protocol.
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6. An electrical system, comprising:
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first and second data transfer ports; first and second circuitries respectively connected to said first and second ports; a switch connected between said first and second ports, said switch having a control input to control opening and closing thereof; a switch controller coupled to said first port and having an output which, in response to a connection request received at said first port, applies a request acknowledgement to said first port, said switch controller having a further output which is connected to said control input of said switch and which, in response to completion of said request acknowledgement, signals said control input to close said switch; and said first and second circuitries operable to communicate therebetween when said switch is closed, said first circuitry operable to provide said connection request and receive said request acknowledgement.
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7. An electrical system, comprising:
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first and second data transfer ports selectively connectable to and disconnectable from one another; first and second circuitries respectively connected to said first and second ports, said first and second circuitries cooperable to communicate therebetween according to a first communication protocol when said ports are connected; acknowledgement circuitry coupled to said first port, said acknowledgement circuitry having an output which, in response to communication at said first port according to a second communication protocol, applies to said first port an acknowledge signal; and said first circuitry operable to provide at said first port said communication according to said second communication protocol.
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Specification