High level message priority assignment by a plurality of message-sending nodes sharing a signal bus
First Claim
1. A node operable in a data processing arrangement including a plurality of the nodes that are capable of communicating with one another via a serial bus, the node comprising:
- a send register for storing a message for transmission on the serial bus, wherein the message comprises at least a data ID including a content identifier inherently exhibiting a first bus arbitration priority;
a message priority module configured to store a second bus arbitration priority contiguous with the data ID of the message; and
a transmitter coupled to the message priority module to receive the message, and to serially transmit onto the serial bus the message as dominant and recessive signal levels in a bit format ordered from the second bus arbitration priority to the first bus arbitration priority.
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Accused Products
Abstract
A system has a plurality of nodes communicating with each other on a serial data path using dominant and recessive signal levels. A dominant signal level sent on the data path by any of the nodes creates a dominant signal level on the data path irrespective of the number of recessive signal levels sent by other nodes. The dominant and recessive signal levels form a series of bits organized into messages by the nodes. Each sending node senses the signal level on the data path bit by bit, and if different from that sent by that sending node, halts further sending of signal levels by that sending node. A priority value generator in each node provides a priority signal encoding a value whose magnitude indicates a relative priority. A message priority module in each node receives the priority signal, and stores the priority value in predetermined leading bits of the message to be sent.
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Citations
22 Claims
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1. A node operable in a data processing arrangement including a plurality of the nodes that are capable of communicating with one another via a serial bus, the node comprising:
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a send register for storing a message for transmission on the serial bus, wherein the message comprises at least a data ID including a content identifier inherently exhibiting a first bus arbitration priority;
a message priority module configured to store a second bus arbitration priority contiguous with the data ID of the message; and
a transmitter coupled to the message priority module to receive the message, and to serially transmit onto the serial bus the message as dominant and recessive signal levels in a bit format ordered from the second bus arbitration priority to the first bus arbitration priority. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A system for enabling a plurality of nodes to arbitrate for access to a serial bus by which the nodes communicate, comprising:
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(a) a sending node comprising;
(i) a send register for storing a first message for transmission on the serial bus, wherein the first message comprises at least a data ID including a content identifier inherently exhibiting a first bus priority;
(ii) a message priority module configured to store a second bus priority contiguous with the data ID of the first message;
(iii) a transmitter coupled to the message priority module to receive the first message, and to serially transmit onto the serial bus the message as dominant and recessive signal levels in a bit format ordered from the second bus priority to the first bus priority; and
(b) a receiving node comprising a monitor circuit coupled to the serial bus to monitor the dominant and recessive signal levels on the serial bus, and configured to disable firther transmission of a second message being transmitted from the receiving node if a dominant signal level is present on the serial bus when a recessive signal level is being transmitted by the receiving node onto the serial bus.
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18. A method for communicating via a serial bus at least one message from a source node to one or more recipient nodes, comprising:
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assembling a message at the source node, wherein the message includes at least a data ID field for providing a content identifier inherently exhibiting a first bus priority, and a priority field for providing a variable priority, and wherein the priority field is assembled immediately preceding the data ID field in an order from leading bits to trailing bits;
transmitting the assembled message bit by bit from the source node onto the serial bus as dominant and recessive signal levels in a bit format ordered to transmit the priority field immediately prior to the data ID field in the order from leading bits to trailing bits;
monitoring the dominant and recessive signal levels on the serial bus;
disabling further transmission of the message from the source node if a dominant signal level associated with the variable priority of at least one of the recipient nodes is present on the serial bus when a recessive signal level associated with the variable priority of the source node is being transmitted onto the serial bus; and
if the variable priorities of the source node and the one or more recipient nodes differ, granting access to the serial bus to the source node or the recipient node having the highest variable priority. - View Dependent Claims (19, 20, 21, 22)
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Specification