Component interconnect with self-clocking data
A communication signal for transmitting a sequence of tokens over an interconnection having three wires in which each of the three wire transmits a signal corresponding to one bit of a 3-bit symbol. The tokens are determined by the transitions between the symbols. In one embodiment, RF emission is minimized and self-clocking is achieved by changing exactly one bit of a symbol at each transition. A receiver detects a transition in the signal on one of the three wires, identifies the transition from the previous and current 3-bit symbols and determines the information token associated with the transition.
1. A method for transmitting a sequence of tokens over an interconnection from a source device to a destination device as a sequence of symbols, the method comprising:
for each new token in the sequence of tokens:
identifying a new symbol for which the new token is assigned to a transition of a set of transitions from a current symbol to a new symbol;
transmitting the new symbol; and
replacing the current symbol with the new symbol,
wherein the current symbol differs from the new symbol in at least one bit position.
2. A method in accordance with claim 1 , wherein the current symbol differs from the new symbol in exactly one bit position.
3. A method in accordance with claim 1 , further comprising transmitting a reference symbol following the transmission of the last new symbol.
4. A method in accordance with claim 1 , wherein the set of symbols includes an abort symbol and further comprising transmitting an abort symbol if transmission is to be aborted.
5. A method in accordance with claim 1 , wherein the set of tokens includes a local address token and at least one external address token.
6. A method in accordance with claim 5 , wherein the sequence of symbols immediately following the reference symbol define a sequence of external address tokens followed by a local address token.
7. A method in accordance with claim 6 , wherein the sequence of external address tokens is interleaved with a sequence of null tokens.
8. A method in accordance with claim 6 , further comprising:
transmitting the sequence of symbols to a first device;
if the first token is an external address token:
selecting a next device according the first token;
transmitting subsequent symbols to the next device.
9. A method in accordance with claim 1 , wherein the symbols comprise 3-bit symbols.
10. A method in accordance with claim 9 , the reference symbol is defined as 111 and wherein the set of symbols includes an abort symbol defined as 000.