Method and apparatus for the detection of the end of a daisy chain
View Patent ↗A method and apparatus for detecting the end of a daisy chain are described. A node receives an M-wide bit input, terminates K bits of the input, shifts and outputs the remaining M-K bits, and drives from the node K bits onto the output.
1. An electrical sensing method for nodes in a daisy chain comprising:
(a) receiving a plurality of electrical signals from a preceding node in said daisy chain, wherein said plurality of electrical signals represents a first quantity, said first quantity including each and every one of said plurality of electrical signals, and wherein one of said plurality of electrical signals is a least significant electrical signal, and wherein except for said one of said plurality of electrical signals another one of said plurality of electrical signals is a most significant electrical signal;
(b) electrically terminating one or more of said plurality of electrical signals, starting said electrical termination at a significant end, wherein said electrically terminated said one or more of said plurality of electrical signals represents a second quantity, said second quantity including each and every one of said electrically terminated said one or more of said plurality of electrical signals;
(c) performing a shift of second quantity bit positions on each of said plurality of electrical signals except for said electrically terminated said one or more of said plurality of electrical signals;
(d) outputting said shifted each of said plurality of electrical signals except for said electrically terminated said one or more of said plurality of electrical signals at a first set of output positions to a following node in said daisy chain;
(e) outputting a third quantity of new electrical signals at a second set of output positions to said following node in said daisy chain, wherein said third quantity is equal in number to said second quantity; and
(f) electrically sensing an electrical state of only one of said third quantity of new electrical signals.
2. The method of claim 1 further comprising (g) providing an optical output based on said electrically sensed electrical state of said only one of said third quantity of new electrical signals.
3. An electrical sensing method for nodes in a daisy chain comprising:
(a) receiving a plurality of electrical signals from a preceding node in said daisy chain, wherein said plurality of electrical signals represents a first quantity, said first quantity including each and every one of said plurality of electrical signals, and wherein one of said plurality of electrical signals is a least significant electrical signal, and wherein except for said one of said plurality of electrical signals another one of said plurality of electrical signals is a most significant electrical signal;
(b) electrically terminating one or more of said plurality of electrical signals, starting said electrical termination at a significant end, wherein said electrically terminated said one or more of said plurality of electrical signals represents a second quantity, said second quantity including each and every one of said electrically terminated said one or more of said plurality of electrical signals;
(c) performing a shift of second quantity bit positions on each of said plurality of electrical signals except for said electrically terminated said one or more of said plurality of electrical signals;
(d) outputting said shifted each of said plurality of electrical signals except for said electrically terminated said one or more of said plurality of electrical signals at a first set of output positions to a following node in said daisy chain;
(e) outputting a third quantity of new electrical signals at a second set of output positions to said following node in said daisy chain, wherein said third quantity is equal in number to said second quantity;
(f) electrically sensing a first electrical state of said third quantity of new electrical signals;
(g) electrically sensing a second electrical state of said each of said plurality of electrical signals except for said electrically terminated said one or more of said plurality of electrical signals and
(h) electrically combining said first electrical state and said second electrical state to produce a single electrical signal indicating a state of said shifted each of said plurality of electrical signals except for said electrically terminated said one or more of said plurality of electrical signals and said new electrical signals.
4. The method of claim 3 further comprising (i) providing an optical output based on said electrically sensed first electrical state and no optical output based on said electrically sensed second electrical state.
5. The method of claim 3 further comprising inverting only said third quantity new electrical signals.
6. A method for detecting if data at any of two or more bit positions presented in a daisy chained node is not received at a daisy chain receiver, said method comprising:
receiving at said daisy chained node an input consisting of a plurality of inputs;
shifting by two or more bit positions said plurality of inputs;
outputting from said daisy chained node an output consisting of said shifted by two or more bit positions said plurality of inputs and said data at two or more bit positions presented in said daisy chained node;
grounding electrically two or more of said plurality of inputs; and
generating based on said output a signal indicative of one or more of said data at any of two or more bit positions presented in said daisy chained node not being received at said daisy chain receiver.