Setting a reference voltage for a bus agent

• US 20070236273A1
• Filed: 04/05/2006
• Published: 10/11/2007
• Est. Priority Date: 04/05/2006
• Status: Abandoned Application

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Hawthorne, Michael, Tawil, Mohamad
• Application Number:
  US11/398,289
• Publication Number:
  US 20070236273A1
• Time in Patent Office: Days
• US Class Current: 327/376
• CPC Class Codes: G06F 13/4072 Drivers or receivers G06F13/4086 takes precedence; for multistate logic circuits H03K19/0002

Abstract

Setting a reference voltage for a bus agent including identifying a present configuration of a bus, the bus including conductive pathways connected to bus agents, the bus agents including computer hardware devices that use the bus for data communications among bus agents, the present configuration of the bus including the identity of the bus, the identities of one or more bus agents presently connected to the bus, and the order in which the bus agents presently are connected to the bus; identifying a reference voltage value for each bus agent; and applying a reference voltage to each bus agents in dependence upon the identified reference voltage value for each bus agent.

Claims

1. A method for setting a reference voltage for a bus agent, the method comprising:

identifying a present configuration of a bus, the bus comprising conductive pathways connected to bus agents, the bus agents comprising computer hardware devices that use the bus for data communications among bus agents, the present configuration of the bus comprising the identity of the bus, the identities of one or more bus agents presently connected to the bus, and the order in which the bus agents presently are connected to the bus;

identifying a reference voltage value for each bus agent; and

applying a reference voltage to each bus agents in dependence upon the identified reference voltage value for each bus agent.

2. The method of claim 1 further comprising creating a list of bus configuration definitions, each bus configuration definition including an identifier for a bus, an identifier for each agent to be connected to the identified bus, an order in which the agents are to be connected to the identified bus, and a reference voltage value for each such agent.

3. The method of claim 2 wherein creating a list of bus configuration definitions further comprises:

identifying high and low reference voltage limits for each agent in each bus configuration definition; and

determining the reference voltage value for each agent in dependence upon the high and low reference voltage limits for each agent.

4. The method of claim 2 wherein identifying a reference voltage value for each agent further comprises:

selecting a bus configuration definition from the list of bus configuration definitions in dependence upon the identity of the bus, the identities of one or more bus agents presently connected to the bus, and the order in which the bus agents presently are connected to the bus; and

identifying a reference voltage value for at least one agent in the present configuration in dependence upon the selected bus configuration definition.

5. The method of claim 4 wherein:

no bus configuration definition in the list of bus configuration definitions exactly matches the present configuration, and

selecting a bus configuration definition from a list of bus configuration definitions further comprises selecting a bus configuration definition that most closely matches the present configuration.

6. The method of claim 5 wherein:

the selected bus configuration definition contains no reference voltage value for at least one agent presently connected to the bus, and

identifying a reference voltage value for at least one agent in the present configuration in dependence upon the selected bus configuration definition further comprises assigning a default reference voltage value of the bus as a reference voltage value for an agent whose reference voltage value is not included in the selected bus configuration definition.

7. An apparatus for setting a reference voltage for a bus agent, the apparatus comprising a computer processor, a computer memory operatively coupled to the computer processor, the computer memory having disposed within it computer program instructions capable of:

identifying a present configuration of a bus, the bus comprising conductive pathways connected to bus agents, the bus agents comprising computer hardware devices that use the bus for data communications among bus agents, the present configuration of the bus comprising the identity of the bus, the identities of one or more bus agents presently connected to the bus, and the order in which the bus agents presently are connected to the bus; and

identifying a reference voltage value for each bus agent;

the apparatus further comprising means for applying a reference voltage to each bus agents in dependence upon the identified reference voltage value for each bus agent.

8. The apparatus of claim 7 further comprising computer program instructions capable of:

creating a list of bus configuration definitions, each bus configuration definition including an identifier for a bus, an identifier for each agent to be connected to the identified bus, an order in which the agents are to be connected to the identified bus, and a reference voltage value for each such agent.

9. The apparatus of claim 8 wherein creating a list of bus configuration definitions further comprises:

identifying high and low reference voltage limits for each agent in each bus configuration definition; and

determining the reference voltage value for each agent in dependence upon the high and low reference voltage limits for each agent.

10. The apparatus of claim 8 wherein identifying a reference voltage value for each agent further comprises:

selecting a bus configuration definition from the list of bus configuration definitions in dependence upon the identity of the bus, the identities of one or more bus agents presently connected to the bus, and the order in which the bus agents presently are connected to the bus; and

identifying a reference voltage value for at least one agent in the present configuration in dependence upon the selected bus configuration definition.

11. The apparatus of claim 10 wherein:

no bus configuration definition in the list of bus configuration definitions exactly matches the present configuration, and

selecting a bus configuration definition from a list of bus configuration definitions further comprises selecting a bus configuration definition that most closely matches the present configuration.

12. The apparatus of claim 11 wherein:

the selected bus configuration definition contains no reference voltage value for at least one agent presently connected to the bus, and

identifying a reference voltage value for at least one agent in the present configuration in dependence upon the selected bus configuration definition further comprises assigning a default reference voltage value of the bus as a reference voltage value for an agent whose reference voltage value is not included in the selected bus configuration definition.

13. A computer program product for setting a reference voltage for a bus agent, the computer program product disposed upon a signal bearing medium, the computer program product comprising computer program instructions capable of:

identifying a present configuration of a bus, the bus comprising conductive pathways connected to bus agents, the bus agents comprising computer hardware devices that use the bus for data communications among bus agents, the present configuration of the bus comprising the identity of the bus, the identities of one or more bus agents presently connected to the bus, and the order in which the bus agents presently are connected to the bus;

identifying a reference voltage value for each bus agent; and

applying a reference voltage to each bus agents in dependence upon the identified reference voltage value for each bus agent.

14. The computer program product of claim 13 wherein the signal bearing medium comprises a recordable medium.

15. The computer program product of claim 13 wherein the signal bearing medium comprises a transmission medium.

16. The computer program product of claim 13 further comprising computer program instructions capable of:

creating a list of bus configuration definitions, each bus configuration definition including an identifier for a bus, an identifier for each agent to be connected to the identified bus, an order in which the agents are to be connected to the identified bus, and a reference voltage value for each such agent.

17. The computer program product of claim 16 wherein creating a list of bus configuration definitions further comprises:

identifying high and low reference voltage limits for each agent in each bus configuration definition; and

determining the reference voltage value for each agent in dependence upon the high and low reference voltage limits for each agent.

18. The computer program product of claim 16 wherein identifying a reference voltage value for each agent further comprises:

selecting a bus configuration definition from the list of bus configuration definitions in dependence upon the identity of the bus, the identities of one or more bus agents presently connected to the bus, and the order in which the bus agents presently are connected to the bus; and

identifying a reference voltage value for at least one agent in the present configuration in dependence upon the selected bus configuration definition.

19. The computer program product of claim 18 wherein:

no bus configuration definition in the list of bus configuration definitions exactly matches the present configuration, and

selecting a bus configuration definition from a list of bus configuration definitions further comprises selecting a bus configuration definition that most closely matches the present configuration.

20. The computer program product of claim 19 wherein:

the selected bus configuration definition contains no reference voltage value for at least one agent presently connected to the bus, and

identifying a reference voltage value for at least one agent in the present configuration in dependence upon the selected bus configuration definition further comprises assigning a default reference voltage value of the bus as a reference voltage value for an agent whose reference voltage value is not included in the selected bus configuration definition.