Encoding of messages onto strobe signals

• US 20040243907A1
• Filed: 05/08/2003
• Published: 12/02/2004
• Est. Priority Date: 05/08/2003
• Status: Active Grant

• Current Assignee: X Corp. (f/k/a Twitter, Inc.) (X Holdings Corp.)
• Original Assignee: International Business Machines Corporation
• Inventors: Hovis, William Paul, Cochran, William Hugh
• Granted Patent: US 7,032,056 B2
• Time in Patent Office: Days
• US Class Current: 714/759
• CPC Class Codes: G06F 13/4273 using a clocked protocol
• CPC Class Codes: Y10S 370/912 Packet communications

Abstract

Methods and apparatus are disclosed for use in an electronic system where data is transmitted over signaling conductors from one electronic component to another using strobe signals accompanying the data. The edge or transition of the strobe signals identifies when, in a window of time, the receiving electronic component should latch the data. In many such systems, data is transmitted over the signaling conductors in the form of a plurality “beats”, of data, proper timing to latch each beat of data being identified by a transition of the strobe signal. Faults in components or errors in transmission must be handled. The present invention discloses apparatus and methods to communicate conditions relevant to data transmitted without requiring additional signaling conductors. The present invention discloses selecting a message from a plurality of messages, encoding the selected message, and transmitting the encoded message on existing strobe lines to communicate the condition encountered.

Claims

1. A method for communicating a message from a first component to a second component in an electronic system, the method comprising the steps of:

determining, on the first component, the message that must be communicated to the second component relevant to a block of data transmitted over a signaling bus; and

transmitting an encoded message respondent to the message from the first component to the second component via a strobe signal associated with the signaling bus, the strobe signal normally providing the second component signal transitions used by the second component to latch data from the signaling bus.

2. The method of claim 1, further comprising the steps of:

partitioning the block of data on the first component into N sub-blocks, each sub-block being of same width as the signaling bus; and

sequentially driving, by the first component, each sub-block onto the signaling bus, each sequential drive of a sub-block being a beat of data on the signaling bus.

3. The method of claim 2, the step of transmitting the encoded message via the strobe signal further comprising the steps of:

determining a message to be transmitted, responsive to a condition on the first component, relevant to the block of data, that must be communicated; and

encoding the message into the encoded message.

4. The method of claim 3, further comprising the steps of:

transmitting a first encoded message comprising a number of transitions on the strobe signal needed by the second component to latch all beats of data at the second component, and no further information is required; and

transmitting a second encoded message differing from the first encoded message if additional information is required.

5. The method of claim 4, wherein the additional information comprises information about one or more of the following conditions:

thermal information measured on the first component;

voltage information measured on the first component;

at least one error in the block of data;

uncertainty about validity of data in the block of data;

unavailability of data in the block of data;

uncertainty regarding a prior request made by the second component;

loss of phase lock loop lock;

loss of delay lock loop lock;

violation of refresh timing specification;

improper self initialization;

improper external initialization; and

uncertainty of a prior request from the second component.

6. The method of claim 3, the step of determining the message further comprising the step of using a look up table to select one message from a plurality of messages, respondent to the condition on the first component.

7. The method of claim 3, the step of determining the message further comprising the step of using logic circuitry to select one message from a plurality of messages, respondent to the condition on the first component.

8. The method of claim 3, the step of encoding the message into the encoded message comprising the step of using a lookup table.

9. The method of claim 3, the step of encoding the message into the encoded message comprising the step of using logic circuits.

10. The method of claim 3, the step of encoding the message into the encoded message comprising directly using the message as the encoded message.

11. The method of claim 1, wherein the step of transmitting an encoded message further comprises transmitting the encoded message via a strobe signal chosen from the group consisting of a unidirectional strobe signal, a bidirectional strobe signal, a differential unidirectional strobe signal, differential bidirectional strobe signal, and a pair of unidirectional strobe signals.

12. An electronic system comprising:

A first component;

a second component coupled to the first component by a signaling bus and at least one strobe signal conductor associated with the signaling bus;

the first component having the ability to encode a first message and transmit the first message to the second component via the at least one associated strobe signal conductor;

The second component having the ability to receive the first message, decode the first message, and use the first message to latch data transmitted on the signaling bus;

the first component having the ability to encode a second message respondent to a condition relevant to a block of data to be transmitted on the signaling bus from the first component and transmit the second message to the second component via the at least one associated strobe signal conductor; and

the second component having the ability to receive the second message, decode the second message, and use the second message to take action other than to latch in data on the signaling bus.

13. The electronic system of claim 12, the first component further comprising:

a first chip status unit in the first component suitable to detect the condition relevant to data transmitted from the first component;

a message determination unit in the first component suitable to select a particular message from a plurality of predetermined messages respondent to input from the first chip status unit; and

a message encoder in the first component suitable to encode the particular message into an encoded message and transmit the encoded message via the at least one associated strobe signal conductor.

14. The electronic system of claim 13, the first chip status unit capable of detecting a condition chosen from the group consisting of:

temperature measurement information on the first component;

at least one error in a block of data to be transmitted from the first component to the second component over the signaling bus;

uncertainty of validity of data in the block of data to be transmitted from the first component to the second component;

unavailability of data in the block of data to be transmitted;

loss of lock in a phase lock loop;

loss of lock in a delay lock loop;

improper self-initialization of the first component;

improper external initialization of the first component;

violation of refresh timing specification;

uncertainty regarding a prior request transmitted from the second component; and

information about voltage measured on the first component.

15. The electronic system of claim 13, the message determination unit further comprising a table look up to select the particular message from the plurality of messages respondent to input from the chip status unit.

16. The electronic system of claim 13, the message determination unit further comprising logic circuitry to select the particular message from the plurality of messages respondent to input from the chip status unit.

17. The electronic system of claim 13, the message encoder comprising logic circuits suitable to encode and transmit the particular message via the at least one associated strobe signal conductor.

18. The electronic system of claim 13, the message encoder comprising a look up table suitable to encode the particular message.

19. The electronic system of claim 12, the second component further comprising:

a message decoder in the second component suitable to receive an encoded message transmitted from the first component on the at least one associated strobe signal conductor and produce a decoded message;

a message interpretation unit in the second component suitable to select the first message and the second message from a plurality of messages respondent to the decoded message; and

a second chip status unit in the second component suitable to perform actions respondent to the first and second messages.

20. The electronic system of claim 19, the second chip status unit capable of performing the action of retransmitting a prior request to the first component, responsive to the second message.

21. The electronic system of claim 19, the second chip status unit capable of performing the action of causing a portion of a block of data received from the first component to be not used, responsive to the second message.

22. The electronic system of claim 19, the second chip status unit capable of performing the action of terminating operation of the electronic system, responsive to the second message.

23. The electronic system of claim 19, the second chip status unit including a condition on the second chip as a determinant of the action.

24. The electronic system of claim 12, wherein the signaling bus is bidirectional.

25. The electronic system of claim 12, wherein the at least one strobe signal conductor is bidirectional.