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US 7,003,605 B2Granted
Method and system for an improved differential form of transitional coding
AssigneeInternational Business Machines Corporation
InventorsDavid John Craft, Charles Ray Johns
Life of this patent
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Abstract
The present invention provides employing differential transitional encoding with a differential bus. Employing the differential transitional encoding comprises dividing the differential bus into one or more groups comprising four bus lines. Employment of the differential bus also comprises asserting half the bus lines of a group during a bus data transfer, thereby defining an asserted set of bus lines and a de-asserted set of bus lines. The method and system further comprises transmitting data by differentially driving two of the bus lines, one bus line per set, by de-asserting one of the bus lines of the asserted set, and asserting one of the bus lines of the de-asserted set.
Claims21
A transitional coding differential bus system, comprising:
- a bus transmitter comprising groups comprising four bus lines;
- the bus transmitter employable to assert half the bus lines at a higher voltage and half the bus lines at a lower voltage, thereby defining an asserted set of bus lines and a de-asserted set of bus lines;
- wherein the bus transmitter is also employable to transmit data by differentially driving two bus lines, one bus line per set, by de-asserting one of the bus lines of the asserted set, and asserting one of the bus-lines of the de-asserted set;
- and
- four or more differential amplifiers coupled to four or more AND gates, wherein the differential amplifiers are functionally coupled to the transmitted signals of the bus transmitter.
2 more elements
A method for encoding data on a differential bus system having at least a bus and a transmitter and a receiver coupled thereto, comprising:
- dividing the bus into at least one group, the group comprising an even number of bus lines;
- establishing a finite set of allowed states for the group, wherein each allowed state always comprises one-half asserted bus lines and one-half de-asserted bus lines;
- initializing the group to a first state comprising one of the established finite set of allowed states;
- receiving, by the transmitter, a first data to be transmitted;
- encoding the received first data by determining a second state comprising one of the established finite set of allowed states other than the first state, in response to the first state, and the received first data, and a set of predetermined encoding rules;
- wherein the set of predetermined encoding rules comprise a set of allowable transitions from a particular first state to a particular second state, wherein the set of allowable transitions comprise asserting only one of the one-half de-asserted bus lines and de-asserting only one of the one-half asserted bus lines, wherein a particular allowable transition from a particular first state to a particular second state represents a particular data value;
- and
- transitioning the group to the determined second state.
5 more elements
A system, comprising:
- a differential receiver coupled to a bus, the bus divided into at least one group, the group comprising an even number of bus lines, the group configured with a finite set of allowed states, wherein each allowed state always comprises one-half asserted bus lines and one-half de-asserted bus lines;
- the differential receiver configured to compare voltages of the bus lines to determine at least one of the finite set of allowed states of the group;
- a decode transition logic coupled to the differential receiver and configured to determine whether a transition has been made from a pre-transition allowed state to a post-transition allowed state;
- a state register coupled to the decode transition logic and configured to store the pre-transition allowed state;
- a decode state logic coupled to the decode transition logic and the state register and configured to determine a particular transition from a finite set of allowed transitions in response to the pre-transition allowed state and post-transition allowed state;
- a decode data logic coupled to the decode transition logic and configured to determine a decoded data in response to the determined transition and a set of predetermined encoding rules;
- and
- wherein the set of predetermined encoding rules comprise the set of allowable transitions, wherein the set of allowable transitions comprise asserting only one of the one-half de-asserted bus lines and de-asserting only one of the one-half asserted bus lines, wherein a particular allowable transition from a particular pre-transition state to a particular post-transition state represents a particular data value.
5 more elements
A processor for encoding data on a differential bus system having at least a bus and a transmitter and a receiver coupled thereto, the processor including a computer program comprising:
- computer code for dividing the bus into at least one group, the group comprising an even number of bus lines;
- computer code for establishing a finite set of allowed states for the group, wherein each allowed state always comprises one-half asserted bus lines and one-half de-asserted bus lines;
- computer code for initializing the group to a first state comprising one of the established finite set of allowed states;
- computer code for receiving, by the transmitter, a first data to be transmitted;
- computer code for encoding the received first data by determining a second state comprising one of the established finite set of allowed states other than the first state, in response to the first state, and the received first data, and a set of predetermined encoding rules;
- wherein the set of predetermined encoding rules comprise a set of allowable transitions from a particular first state to a particular second state, wherein the set of allowable transitions comprise asserting only one of the one-half de-asserted bus lines and de-asserting only one of the one-half asserted bus lines, wherein a particular allowable transition from a particular first state to a particular second state represents a particular data value;
- and
- computer code for transitioning the group to the determined second state.
5 more elements
Dependencies are inferred from the claim text.