Multi-user serial data bus
First Claim
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1. A data communications system, comprising:
- (a) a serial data bus including at least first and second conductors;
(b) a plurality of peripheral units each having a multi-bit pre-assigned address indicative of a pre-assigned priority and including means coupled to said serial data bus for placing a first bit of its pre-assigned address on said first conductor and the remaining bits of its pre-assigned address on said first conductor in response to clocking information on said second conductor, means for detecting addresses placed on said first conductor, and means for releasing said first conductor in response to detection of an address having a having priority than its pre-assigned address; and
(c) a bus control unit coupled to said serial data bus for detecting peripheral unit addresses placed on said first conductor and placing the clocking information on said second conductor in response thereto.
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Abstract
A multiple device serial data bus and signalling scheme is described. The serial data bus allows for inter-peripheral communication at a data rate established by a bus control unit. Clocking information is extracted from data communicated from the bus controller to the peripheral devices. Additional conductors for clock information are not required. In addition an arbitration scheme is provided to eliminate bus contention if several units request service simultaneously. The multiple device serial data bus is utilized on an as required basis and may communicate information at a variety of data rates.
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Citations
13 Claims
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1. A data communications system, comprising:
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(a) a serial data bus including at least first and second conductors; (b) a plurality of peripheral units each having a multi-bit pre-assigned address indicative of a pre-assigned priority and including means coupled to said serial data bus for placing a first bit of its pre-assigned address on said first conductor and the remaining bits of its pre-assigned address on said first conductor in response to clocking information on said second conductor, means for detecting addresses placed on said first conductor, and means for releasing said first conductor in response to detection of an address having a having priority than its pre-assigned address; and (c) a bus control unit coupled to said serial data bus for detecting peripheral unit addresses placed on said first conductor and placing the clocking information on said second conductor in response thereto. - View Dependent Claims (2, 3)
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4. A peripheral unit coupled by a serial data bus to a control unit of a data communications system, each peripheral unit having a multi-bit pre-assigned address indicative of a pre-assigned priority, said serial data bus including at least first and second conductors, and said bus control unit coupled to said serial data bus for detecting peripheral unit addresses placed on said first conductor and placing clocking information on said second conductor in response thereto, said peripheral unit comprising:
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means coupled to said serial data bus for placing a first bit of its pre-assigned address on said first conductor and the remaining bits of its pre-assigned address on said first conductor in response to the clocking information on said second conductor; means for detecting addresses placed on said first conductor; and means for releasing said first conductor in response to detection of an address having a higher priority than its pre-assinged address.
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5. A data communications system, comprising:
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(a) a serial data bus including at least first, second and third conductors; (b) a plurality of peripheral units each having a multi-bit pre-assigned address indicative of a pre-assigned priority and including means coupled to said serial data bus for placing a first bit of its pre-assigned address on said first conductor and the remaining bits of its pre-assigned address on said first conductor in response to clocking information on at least one of said second and third conductors, means for detecting addresses placed on said first conductor, and means for releasing said first conductor in response to detection of an address having a higher priority than its pre-assigned address; and (c) a bus control unit coupled to said serial data bus for detecting peripheral unit addresses placed on said first conductor and placing the clocking information on said one of said second and third conductors in response thereto. - View Dependent Claims (6, 7)
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8. A peripheral unit coupled by a serial data bus to a control unit of a data communications system, each peripheral unit having a multi-bit pre-assigned address indicative of a pre-assigned priority, said serial data bus including at least first, second and third conductors, and said bus control unit coupled to said serial data bus for detecting peripheral unit addresses placed on said first conductor and placing clocking information on at least one of said second and third conductors in response thereto, said peripheral unit comprising:
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means coupled to said serial data bus for placing a first bit of its pre-assigned address on said first conductor and the remaining bits of its pre-assigned address on said first conductor in response to the clocking information on said one of said second and third conductors; means for detecting addresses placed on said first conductor; and means for releasing said first conductor in response to detection of an address having a higher priority than its pre-assigned address.
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9. A method for controlling access to a serial data bus having at least first and second conductors for coupling a bus control unit to a plurality of peripheral units each having a multi-bit pre-assigned address indicative of a pre-assigned priority, said bus control unit coupled to said serial data bus for detecting peripheral unit addresses placed on said first conductor and placing clocking information on said second conductor in response thereto, said method of access for each peripheral unit comprising the steps of:
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(a) placing a first bit of the pre-assigned address on the first conductor to request service; (b) placing the remaining bits of the pre-assigned address on the first conductor in response to clocking information on the second conductor from the bus control unit; (c) monitoring the first conductor to detect the address of a higher priority peripheral device; and (d) releasing the first conductor if a higher priority peripheral device has requested service on the bus. - View Dependent Claims (10, 11, 12, 13)
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Specification