Method and apparatus for configuring signal lines according to idle codes

1. A method, comprising:

for each of a plurality of data transmission lanes, generating, by an encoder circuit, an idle code in response to both an idle control signal that indicates when valid data is not being transmitted on the data transmission lane and a lane control signal that indicates if the data transmission lane is logically grouped with any other data transmission lane.

2. The method of claim 1 , wherein:

generating the idle code comprises

generating at least a first type idle code when the corresponding data transmission lane is a first lane of a group of such lanes, and

generating at least a second type idle code when the corresponding data transmission lane is not a first lane of a group of such lanes.

3. The method of claim 2 , wherein:

generating the idle code further comprises

selecting either the first type idle code or second type idle code in response to a lane control value that indicates whether or not the corresponding data transmission lane is a first lane of a group of such lanes.

4. The method of claim 2 , wherein:

generating the idle code further comprises

generating the first type idle code when the corresponding data transmission lane is a first lane of a group of such lanes and a periodic strobe signal has one value,

generating a third type idle code when the corresponding data transmission lane is the first lane of a group of such lanes and the periodic strobe signal has a second value,

generating the second type idle code when the corresponding data transmission lane is not the first lane of a group of such lanes and the periodic strobe signal has the one value, and

generating a fourth type idle code when the corresponding data transmission lane is not the first lane of a group of such lanes and the periodic strobe signal has the second value.

5. The method of claim 4 , further comprising:

for each data transmission lane, outputting the generated idle code value in parallel with the periodic strobe signal.

6. The method of claim 1 , wherein:

generating the idle code comprises

selectively coupling the corresponding data transmission lane to either a first idle code source or a second idle code source in response to a lane control value.

7. The method of claim 6 , further comprising:

transmitting data on the plurality of data transmission lanes according to a logical grouping of such data transmission lanes established by previously generated idle codes.

8. A method of controlling logical grouping of parallel data transmission lanes, comprising:

indicating, by an encoder circuit, a change from one grouping of the parallel data transmission lanes to another grouping by transmitting idle codes that demarcate group boundaries of the parallel data transmission lanes.

9. The method of claim 8 , wherein:

transmitting idle codes that demarcate group boundaries of the data transmission lanes comprises transmitting at least a first idle code on a data transmission lane if the data transmission lane is the first or only lane of a group such lanes.

10. The method claim 9 , wherein:

transmitting idle codes that demarcate group boundaries of the data transmission lanes further comprises transmitting at least a second idle code on a data transmission lane if the data transmission lane is not the first or only lane of a group such lanes.

11. The method of claim 8 , wherein:

transmitting idle codes that demarcate group boundaries of the parallel data transmission lanes comprises transmitting different idle codes according to a periodic strobe signal.

12. The method of claim 8 , wherein:

transmitting idle codes that demarcate group boundaries of the parallel data transmission lanes comprises outputting idle codes from an encoder circuit coupled to each data transmission lane.

13. The method of claim 8 , further comprises:

after transmitting the idle codes, transmitting data on the data transmission lanes according to the grouping indicated by the idle codes.

14. A data encoding system for transmitting data codes on sets of parallel lines, comprising:

a plurality of encoder circuits, wherein each encoder circuit includes a data output coupled to a corresponding set of parallel lines, and includes a data input configured to receive a data value for encoding, an idle code input configured to receive at least one of two idle codes, and a lane control input coupled to receive an lane control value that indicates whether or not the set of parallel lines is the first or only set of a group of such sets.

15. The data encoding system of claim 14 , wherein:

each encoder circuit comprises code generating structure to generate the one of at least two idle codes in response to at least the lane control value and an idle control value that indicates when the set of parallel lines is idle.

16. The data encoding system of claim 15 , wherein:

the code generating structure to generate the one idle code from at least four idle codes in response to at least the lane control value, the idle control value, and a periodic strobe signal.

17. The data encoding system of claim 14 , wherein:

each encoder circuit comprises an idle code multiplexer (MUX) that includes a first data input coupled to receive a second idle code value, and a control input coupled to receive the lane control value.

18. The data encoding system of claim 17 , wherein:

each encoder circuit further comprises a data select MUX that includes a first data input coupled to a data output of the corresponding idle code MUX, a second data input coupled to a data source, a data output coupled to the corresponding set of parallel lines, and a control input coupled to receive an idle control value that indicates when the corresponding set of parallel lines is idle.

19. The data encoding system of claim 14 , further comprising:

an idle code circuit corresponding to each encoder circuit, each idle code circuit to provide one of at least two different idle codes according to a signal received at a select input; and

a periodic strobe signal source coupled to the select input of the idle code circuit.

20. The data encoding system of claim 19 , wherein

each encoder circuit is configured to output the strobe signal received at the periodic strobe signal source.