Simultaneous serial transmission of messages with bit-arbitrated selection of the numerically largest or smallest value in the messages' data fields

An apparatus comprising:

• a bus interface configured to couple to a serial data bus that uses dominant and recessive signals to represent message bits, wherein the nodes of the data bus use bitwise arbitration so that simultaneous transmission on the bus of the dominant signal by at least one of the nodes and the recessive signal by the other nodes results in the dominant signal being detectable on the bus, wherein the nodes are configured to cancel transmission of a selected message if bitwise arbitration is lost while sending the selected message and subsequently retransmit the selected message when the bus is available;
• a sensing device configured to generate data;
• a message processor coupled to the bus interface and sensing device, the processor configured with instructions that cause the processor to:
• associate the apparatus with a report message group identifier that is common to the apparatus and at least one of the nodes;
• receive a report query message via the bus, wherein the report query message is associated with the report message group identifier;
• provide a response message in response to the report query message, wherein the response message comprises higher-order bits representing a report message header and lower-order bits representing the data generated by the sensing device;
• transmit the response message to the serial data bus;
• determine that the apparatus has lost bitwise arbitration to a second message while sending the lower-order bits of the response message;
• and
• canceling retransmission of the response message based on a) determining that the report query message is associated with the report message group identifier, and b) losing the bitwise arbitration while sending the lower-order bits, wherein the second message has an identical report message header portion as the response message.

A system comprising:

• a serial data bus that uses dominant and recessive signals to represent message bits;
• a plurality of nodes coupled via the serial data bus, wherein the nodes use bitwise arbitration so that simultaneous transmission on the bus of the dominant signal by at least one of the nodes and the recessive signal by the other nodes results in the dominant signal being detectable on the bus, wherein the nodes are configured to cancel transmission of a selected message if bitwise arbitration is lost while sending the selected message and subsequently retransmit the selected message when the bus is available, wherein at least two of the nodes are associated with a common report message group identifier and are configured to:
• respond to the same report query message by simultaneously transmitting respective response messages onto the serial data bus, wherein the report query message is associated with the report message group identifier;
• selecting one of the response messages to be transmitted onto the serial bus, and cancelling retransmission of the others of the response messages onto the serial data bus, and wherein the selected one response message is determined based on a measured data value encoded in the selected one response message that is an extremum relative to other measured data values encoded in the other response messages, and wherein the determination that the measured data value is the extremum is determined via bitwise arbitration, and wherein canceling retransmission of the others of the response messages occurs in response to a) the report query message being associated with the report message group identifier, and b) the others of the response messages losing bitwise arbitration to the selected one response message.