Method and system for resynchronizing a phase-shifted received data stream with a master clock

An apparatus for resynchronizing a received data stream with a master clock having a master clock frequency, wherein said received data stream is clocked with a received data clock that is out of phase with said master clock by an arbitrary number of degrees, said apparatus comprising:

• means for comparing, at a resynchronization clock frequency, a master clock value and a received data clock value for a predetermined number of times to produce comparison results;
• means for producing a relative phase indicator based upon said comparison results;
• means for sampling said received data stream at a rising edge of said master clock to produce a resynchronized data stream in response to said relative phase indicator exceeding a predetermined phase shift threshold and said received data stream being clocked with a rising edge of said received data clock;
• means for sampling said received data stream at a falling edge of said master clock to produce said resynchronized data stream in response to said relative phase indicator being less than said predetermined phase shift threshold and said received data stream being clocked with said rising edge of said received data clock;
• means for sampling said received data stream at said falling edge of said master clock to produce a resynchronized data stream in response to said relative phase indicator exceeding a predetermined phase shift threshold and said received data stream being clocked with a falling edge of said received data clock;
• and
• means for sampling said received data stream at said rising edge of said master clock to produce said resynchronized data stream in response to said relative phase indicator being less than said predetermined phase shift threshold and said received data stream being clocked with said falling edge of said received data clock, wherein said resynchronized data stream is synchronized with said master clock and contains the data of said received data stream.

A data processing system for resynchronizing a received data stream with a master clock having a master clock frequency, said data processing system comprising:

• a master clock for producing a master clock signal and an inverted master clock signal;
• a resynchronization clock for producing a resynchronization clock signal;
• a received clock source for producing a received clock signal;
• a comparator having inputs coupled to said master clock signal and said received clock signal, wherein said comparator produces a comparison result that indicates whether said master clock signal and said received clock signal are substantially equal;
• a counter responsive to said comparison result for periodically counting said comparison result for a predetermined number of cycles of said resynchronization clock signal to produce a relative phase indicator;
• a master clock polarity selector for selecting said master clock signal or said inverted master clock signal in response to said relative phase indicator;
• a data resynchronizing register having an input coupled to said received data stream, said data resynchronizing register for reclocking said received data stream based on said master clock polarity selector to produce a resynchronized data stream.

A method in a data processing system for resynchronizing a received data stream with a master clock having a master clock frequency, wherein said received data stream is clocked with a received data clock that is out of phase with said master clock by an arbitrary number of degrees, said method comprising the steps of:

• at a resynchronization clock frequency, comparing a master clock value and a received data clock value for a predetermined number of times to produce comparison results;
• based upon said comparison results, producing a relative phase indicator;
• and
• in response to said relative phase indicator exceeding a predetermined phase shift threshold and said received data stream being clocked with a rising edge of said received data clock, sampling said received data stream at a rising edge of said master clock to produce a resynchronized data stream.

A method in a data processing system for resynchronizing a received data stream with a master clock having a master clock frequency, wherein said received data stream is clocked with a received data clock that is out of phase with said master clock by an arbitrary number of degrees, said method comprising the steps of:

• at a resynchronization clock frequency, comparing a master clock value and a received data clock value for a predetermined number of times to produce comparison results;
• based upon said comparison results, producing a relative phase indicator;
• and
• in response to said relative phase indicator being less than said predetermined phase shift threshold and said received data stream being clocked with said rising edge of said received data clock, sampling said received data stream at a falling edge of said master clock to produce said resynchronized data stream.

A method in a data processing system for resynchronizing a received data stream with a master clock having a master clock frequency, wherein said received data stream is clocked with a received data clock that is out of phase with said master clock by an arbitrary number of degrees, said method comprising the steps of:

• at a resynchronization clock frequency, comparing a master clock value and a received data clock value for a predetermined number of times to produce comparison results;
• based upon said comparison results, producing a relative phase indicator;
• and
• in response to said relative phase indicator exceeding a predetermined phase shift threshold and said received data stream being clocked with a falling edge of said received data clock, sampling said received data stream at said rising edge of said master clock to produce a resynchronized data stream.

A method in a data processing system for resynchronizing a received data stream with a master clock having a master clock frequency, wherein said received data stream is clocked with a received data clock that is out of phase with said master clock by an arbitrary number of degrees, said method comprising the steps of:

• at a resynchronization clock frequency, comparing a master clock value and a received data clock value for a predetermined number of times to produce comparison results;
• based upon said comparison results, producing a relative phase indicator;
• and
• in response to said relative phase indicator being less than said predetermined phase shift threshold and said received data stream being clocked with said falling edge of said received data clock, sampling said received data stream at said falling edge of said master clock to produce said resynchronized data stream.