Backplane bus system including a plurality of nodes

Claim 1

A system for transmitting and receiving data between a plurality of nodes via a bus, comprising: a bus having a current source; a plurality of nodes, more than one node being capable of driving the bus simultaneously to transfer data, the nodes supplying together with the current source of the bus current for the transfer of data such that during such transfer of data the state of the bus transitions between one predetermined voltage level and another predetermined voltage level; means for individually connecting each of said nodes to the bus; a driver in each node designed to supply current to the bus in parallel with the current source for the transfer of data; coupling resistor means in each node for coupling its driver to the connecting means for such node, and during occasions when such node is driving the bus to one predetermined voltage level simultaneously with at least another of the plurality of nodes driving the bus to another predetermined voltage level, for limiting the current flowing through its driver and avoiding damage to said driver.

Claim 2

A system for transmitting and receiving data between a plurality of nodes via a bus, comprising: a bus having a current source; a plurality of nodes, more than one node being capable of driving the bus simultaneously to transfer data, the nodes supplying together with the current source of the bus current for the transfer of data such that during such transfer of data the state of the bus transitions between one predetermined voltage level and another predetermined voltage level; means for individually connecting each of said nodes to the bus; a driver in each node designed to supply current to the bus in parallel with the current source for the transfer of data; coupling resistor means in each node for coupling its driver to the connecting means for such node, and during occasions when such node is driving the bus to one predetermined voltage level simultaneously with at least another of the plurality of nodes driving the bus to another predetermined voltage level, for limiting the current flowing through its driver and avoiding damage to said driver.

Claim 8

A system for transmitting and receiving data between a plurality of nodes via a bus, comprising: a bus having a current source which establishes a nominal voltage level absent any node driving the bus; a plurality of nodes, more than one node being capable of driving the bus simultaneously to transfer data, the nodes supplying together with the current source of the bus current for the transfer of data such that during such transfer of data the state of the bus transitions between a first predetermined voltage level and a second predetermined voltage level passing through said nominal voltage level; means for individually connecting each of said nodes to the bus; a driver in each node designed to supply current to the bus in parallel with the current source for the transfer of data; a coupling resistor in each node for coupling its driver to the connecting means for such node, each coupling resistor having a predetermined resistance value chosen to limit the current flowing through its driver to avoid damage to its driver during occasions when such node is driving the bus to the first predetermined voltage level simultaneously with at least another of the plurality of nodes driving the bus to the second predetermined voltage level.

Claim 9

A system for transmitting and receiving data between a plurality of nodes via a bus, comprising: a bus having a current source which establishes a nominal voltage level absent any node driving the bus; a plurality of nodes, more than one node being capable of driving the bus simultaneously to transfer data, the nodes supplying together with the current source of the bus current for the transfer of data such that during such transfer of data the state of the bus transitions between a first predetermined voltage level and a second predetermined voltage level passing through said nominal voltage level; means for individually connecting each of said nodes to the bus; a driver in each node designed to supply current to the bus in parallel with the current source for the transfer of data; a coupling resistor in each node for coupling its driver to the connecting means for such node, each coupling resistor having a predetermined resistance value chosen to limit the current flowing through its driver to avoid damage to its driver during occasions when such node is driving the bus to the first predetermined voltage level simultaneously with at least another of the plurality of nodes driving the bus to the second predetermined voltage level.

Claim 13

A system for transmitting and receiving data between a plurality of nodes via a bus, comprising: a bus having a current source; a plurality of nodes, more than one node being capable of driving the bus simultaneously to transfer data, the nodes supplying together with the current source of the bus current for the transfer of data such that during such transfer of data the state of the bus transitions between one predetermined voltage level and another predetermined voltage level; means for individually connecting each of said nodes to the bus; logic circuitry in each node for transmitting and receiving data via the bus; a driver in each node coupled to the logic circuitry and designed to supply current for the data transfer in parallel with the current source of the bus, such that the current flowing through such driver is at an acceptable level; linear resistive means, having a predetermined resistance value, in each node for coupling its driver to the connecting means for such node and, during occasions when such node is driving the bus to one predetermined voltage level simultaneously with at least another of the plurality of nodes driving the bus to another predetermined voltage level, for preventing the current flowing through its driver from exceeding said acceptable level so as to avoid damage to its driver.

Claim 14

A system for transmitting and receiving data between a plurality of nodes via a bus, comprising: a bus having a current source; a plurality of nodes, more than one node being capable of driving the bus simultaneously to transfer data, the nodes supplying together with the current source of the bus current for the transfer of data such that during such transfer of data the state of the bus transitions between one predetermined voltage level and another predetermined voltage level; means for individually connecting each of said nodes to the bus; logic circuitry in each node for transmitting and receiving data via the bus; a driver in each node coupled to the logic circuitry and designed to supply current for the data transfer in parallel with the current source of the bus, such that the current flowing through such driver is at an acceptable level; linear resistive means, having a predetermined resistance value, in each node for coupling its driver to the connecting means for such node and, during occasions when such node is driving the bus to one predetermined voltage level simultaneously with at least another of the plurality of nodes driving the bus to another predetermined voltage level, for preventing the current flowing through its driver from exceeding said acceptable level so as to avoid damage to its driver.

Claim 20

A system for transmitting and receiving data between a plurality of nodes via a bus, comprising: a bus having two ends and a current source, said current source comprising first and second resistors and first and second supply voltages, said first resistor connecting one end of said bus to said first supply voltage and said second resistor connecting the other end of said bus to said second supply voltage; a plurality of nodes, more than one node being capable of driving the bus simultaneously to transfer data, the nodes supplying together with the current source of the bus current for the transfer of data such that during such transfer of data the state of the bus transitions between one predetermined voltage level and another predetermined voltage level; means for individually connecting each of said nodes to the bus; a CMOS tri-state driver in each node designed to supply current to the bus in parallel with the current source for the transfer of data; a coupling resistor, having a predetermined resistance value, in each node for coupling its CMOS tri-state driver to the connecting means for such node, and during occasions when such node is driving the bus to one predetermined voltage level simultaneously with at least another of the plurality of nodes driving the bus to another predetermined voltage level, for limiting the current flowing through its tri-state driver and avoiding damage to said driver; said coupling resistor in each node acting in conjunction with the current source of the bus to limit the transitions of the bus to the predetermined voltage levels, the predetermined resistance value of the coupling resistor being also chosen to terminate the bus; and logic circuitry in each node for transmitting and receiving data via the bus, and wherein the CMOS tri-state driver in each node is coupled to the logic circuitry.

Claim 21

A system for transmitting and receiving data between a plurality of nodes via a bus, comprising: a bus having two ends and a current source, said current source comprising first and second resistors and first and second supply voltages, said first resistor connecting one end of said bus to said first supply voltage and said second resistor connecting the other end of said bus to said second supply voltage; a plurality of nodes, more than one node being capable of driving the bus simultaneously to transfer data, the nodes supplying together with the current source of the bus current for the transfer of data such that during such transfer of data the state of the bus transitions between one predetermined voltage level and another predetermined voltage level; means for individually connecting each of said nodes to the bus; a CMOS tri-state driver in each node designed to supply current to the bus in parallel with the current source for the transfer of data; a coupling resistor, having a predetermined resistance value, in each node for coupling its CMOS tri-state driver to the connecting means for such node, and during occasions when such node is driving the bus to one predetermined voltage level simultaneously with at least another of the plurality of nodes driving the bus to another predetermined voltage level, for limiting the current flowing through its tri-state driver and avoiding damage to said driver; said coupling resistor in each node acting in conjunction with the current source of the bus to limit the transitions of the bus to the predetermined voltage levels, the predetermined resistance value of the coupling resistor being also chosen to terminate the bus; and logic circuitry in each node for transmitting and receiving data via the bus, and wherein the CMOS tri-state driver in each node is coupled to the logic circuitry.

Claim 22

A system for transmitting and receiving data between a plurality of nodes via a bus, comprising: a bus having a current source; a plurality of nodes, more than one node being capable of driving the bus simultaneously to transfer data, the nodes supplying together with the current source of the bus current for the transfer of data such that during such transfer of data the state of the bus transitions between one predetermined voltage level and another predetermined voltage level; means for individually connecting each of said nodes to the bus; logic circuitry in each node for transmitting and receiving data via the bus; a tri-state driver in each node coupled to the logic circuitry and designed to supply current for the data transfer in parallel with the current source of the bus, such that the current flowing through such driver is at an acceptable level; a coupling resistor, having a predetermined resistance value, in each node for coupling its tri-state driver to the connecting means for such node and, during occasions when such node is driving the bus to one predetermined voltage level simultaneously with at least another of the plurality of nodes driving the bus to another predetermined voltage level, for preventing the current flowing through its tri-state driver from exceeding said acceptable level so as to avoid damage to its tri-state driver.

Claim 23

A system for transmitting and receiving data between a plurality of nodes via a bus, comprising: a bus having a current source; a plurality of nodes, more than one node being capable of driving the bus simultaneously to transfer data, the nodes supplying together with the current source of the bus current for the transfer of data such that during such transfer of data the state of the bus transitions between one predetermined voltage level and another predetermined voltage level; means for individually connecting each of said nodes to the bus; logic circuitry in each node for transmitting and receiving data via the bus; a tri-state driver in each node coupled to the logic circuitry and designed to supply current for the data transfer in parallel with the current source of the bus, such that the current flowing through such driver is at an acceptable level; a coupling resistor, having a predetermined resistance value, in each node for coupling its tri-state driver to the connecting means for such node and, during occasions when such node is driving the bus to one predetermined voltage level simultaneously with at least another of the plurality of nodes driving the bus to another predetermined voltage level, for preventing the current flowing through its tri-state driver from exceeding said acceptable level so as to avoid damage to its tri-state driver.