Physical coding sublayer for a multi-pair gigabit transceiver
A physical coding sublayer (PCS) transmitter circuit generates a plurality of encoded symbols according to a transmission standard. A symbol skewer skews the plurality of encoded symbols within a symbol clock time. A physical coding sublayer (PCS) receiver core circuit decodes a plurality of symbols based on encoding parameters. The symbols are transmitted using the encoding parameters according to a transmission standard. The received symbols are skewed within a symbol clock time by respective skew intervals. A PCS receiver encoder generator generates the encoding parameters.
1. A receiver operable to receive quinary symbols encoded according to encoding parameters, the symbols being skewed with respect to each other by respective skew intervals, the receiver comprising:
a physical coding sublayer (PCS) receiver encoder generator operable to regenerate at least a portion of the encoding parameters; and
a PCS receiver core circuit operable to generate skew adjustment signals for adjusting the skew intervals of the quinary encoded symbols in response to at least a portion of the regenerated encoding parameters.
2. The apparatus of claim 1 wherein the PCS receiver core circuit comprises:
a pair swap multiplexer to swap the symbols according to a pair select word; and
an alignment and acquisition state machine (AASM) coupled to the pair swap multiplexer to acquire the swapped symbols.
3. The apparatus of claim 2 wherein the symbols include a codegroup of first, second, third, and fourth symbols, each of the symbols having a polarity and a skew setting, the skew setting corresponding to a respective one of the skew intervals.
4. The apparatus of claim 3 wherein the PCS receiver encoder generator comprises:
a scrambler generator to generate scrambling parameters upon being loaded with a load value, the scrambler generator providing a scrambler output;
a scrambled code (SC) generator coupled to the scrambler generator to generate an SC parameter from the scrambling parameters; and
an idle generator coupled to the SC generator to generate idle codewords representative of the four symbols transmitted in an idle mode using the SC parameter, the idle codewords corresponding to the encoding parameters.
5. The apparatus of claim 4 wherein the AASM comprises an initialization state, a scrambler load state, a scrambler verification state, and a symbol find state.
6. The apparatus of claim 5 wherein the initialization state initializes acquisition variables.
7. The apparatus of claim 5 wherein the scrambler load state loads the load value to the scrambler generator based on one of the swapped symbols.
8. The apparatus of claim 5 wherein the scrambler verification state compares one of the swapped symbols with the scrambler output.
9. The apparatus of claim 5 wherein the symbol find state compares one of the swapped symbols with one of the idle codewords.
10. The apparatus of claim 9 wherein the symbol find state generates a failure condition if one of the swapped symbols is not matched with one of the idle codewords after a predetermined number of comparisons.
11. The apparatus of claim 10 wherein the AASM returns to the initialization state when the failure condition occurs.
12. In a receiver arranged to receive quinary symbols encoded according to encoding parameters, the symbols being skewed with respect to each other by respective skew intervals, a method comprising the operations of:
regenerating at least a portion of the encoding parameters; and
decoding the quinary encoded symbols in response to at least a portion of the regenerated encoding parameters.
13. The method of claim 12 wherein the operation of decoding the symbols comprises the operations of:
swapping the symbols according to a pair select word; and
acquiring the swapped symbols.
14. The method of claim 13 wherein the symbols include a codegroup of first, second, third, and fourth symbols, each of the symbols having a polarity and a skew setting, the skew setting corresponding to a respective one of the skew intervals.
15. The method of claim 14 wherein the operation of regenerating the encoding parameters comprises the operations of:
generating scrambling parameters upon being loaded by a load value;
providing a scrambler output;
generating a scrambled code (SC) parameter from the scrambling parameters; and
generating idle codewords representative of the four symbols transmitted in an idle mode using the SC parameter, the idle codewords corresponding to the encoding parameters.
16. The method of claim 15 wherein the operation of acquiring the symbols comprises the operations of:
initializing acquisition variables;
loading the load value based on one of the swapped symbols;
comparing one of the swapped symbols with the scrambler output;
comparing one of the swapped symbols with one of the idle codewords;
generating a failure condition if one of the swapped symbols is not matched with one of the idle codewords after a predetermined number of comparisons; and
returning to initializing when the failure condition occurs.
17. A system comprising:
a medium independent interface;
a communication medium including a plurality of twisted pair cables; and
a receiver coupled to the medium independent interface and the communication medium, the receiver being operable to receive quinary symbols encoded according to encoding parameters, the symbols being skewed with respect to each other by respective skew intervals, the receiver comprising:
a PCS receiver encoder generator operable to regenerate at least a portion of the encoding parameters; and
a physical coding sublayer (PCS) receiver core circuit operable to generate skew adjustment signals for adjusting the skew intervals of the quinary encoded symbols in response to at least a portion of the regenerated encoding parameters.
18. The system of claim 17 wherein the PCS receiver core circuit comprises:
a pair swap multiplexer to swap the symbols according to a pair select word; and
an alignment and acquisition state machine (AASM) coupled to the pair swap multiplexer to acquire the swapped symbols.
19. The system of claim 18 wherein the symbols include a codegroup of first, second, third, and fourth symbols, each of the symbols having a polarity and a skew setting, the skew setting corresponding to a respective one of the skew intervals.
20. The system of claim 19 wherein the PCS receiver encoder generator comprises:
a scrambler generator to generate scrambling parameters upon being loaded by a load value, the scrambler generator providing a scrambler output;
a scrambled code (SC) generator coupled to the scrambler generator to generate an SC parameter from the scrambling parameters; and
an idle generator coupled to the SC generator to generate idle codewords representative of the four symbols transmitted in an idle mode using the SC parameter, the idle codewords corresponding to the encoding parameters.
21. The system of claim 20 wherein the AASM comprises an initialization state, a scrambler load state, a scrambler verification state, and a symbol find state.
22. The system of claim 21 wherein the initialization state initializes acquisition variables.
23. The system of claim 21 wherein the scrambler load state loads the load value to the scrambler generator based on one of the swapped symbols.
24. The system of claim 21 wherein the scrambler verification state compares one of the swapped symbols with the scrambler output.
25. The system of claim 21 wherein the symbol find state compares one of the swapped symbols with one of the idle codewords.
26. The system of claim 25 wherein the symbol find state generates a failure condition if one of the swapped symbols is not matched with one of the idle codewords after a predetermined number of comparisons.
27. The system of claim 26 wherein the AASM returns to the initialization state when the failure condition occurs.