Systems and methods for accurate transfer margin communication

1. A data processing system, the system comprising:

a sampling latch operable to sample a received serial data input and provide a corresponding serial data output;

a first duration margin determination circuit operable to: define a first contour of a data signal eye corresponding to the serial data output over a first number of bit periods, and determine a first margin characteristic based upon the first contour;

a second duration margin determination circuit operable to: define a second contour of the data signal eye corresponding to the serial data output over a second number of bit periods, and determine a second margin characteristic based upon the second contour;

a margin normalization circuit operable to calculate a normalized value based upon a combination of the first margin characteristic and the second margin characteristic; and

a transmission circuit operable to transmit an output to a requesting device, wherein the output transmitted by the transmission circuit is indicative of the normalized value.

2. The system of claim 1 , the system further comprising:

a target margin calculation circuit operable to determine a target margin value; and

wherein the margin normalization circuit is further operable to multiply the target margin value by the normalized value to yield a margin output that is included in the output transmitted by the transmission circuit.

3. The system of claim 2 , wherein the target margin calculation circuit is a third duration margin determination circuit operable to: define a third contour of the data signal eye corresponding to the serial data output over a third number of bit periods, and determine the target margin characteristic based upon the third contour, and wherein the third number of bit periods is less than both the first number of bit periods and the second number of bit periods.

4. The system of claim 3 , wherein the target margin characteristic is a maximum voltage and wherein the transmission circuit is operable to transmit the maximum voltage to the requesting device via a communication bus.

5. The system of claim 2 , the system further comprising:

a margin output circuit operable to format the margin output to yield a formatted margin output, wherein the transmission circuit is operable to transmit the formatted margin output to the recipient device.

6. The system of claim 5 , wherein the received serial data input is received from the recipient device via a bus.

7. The system of claim 6 , wherein the bus is a PCie™ bus.

8. The system of claim 1 , wherein the second number of bit periods is at least ten times greater than the first number of bit periods.

9. The system of claim 8 , wherein the second number of bit periods is greater than one hundred million bit periods and the first number of bit periods is less that one hundred thousand bit periods.

10. The system of claim 2 , wherein the first margin characteristic is a first lateral margin, the second margin characteristic is a second lateral margin, and the target margin value is a target margin voltage.

11. The system of claim 2 , wherein the first margin characteristic is a first margin voltage, the second margin characteristic is a second margin voltage, and the target margin value is a target lateral margin.

12. The system of claim 1 , wherein calculating the normalized value based upon the combination of the first margin characteristic and the second margin characteristic includes dividing the second margin characteristic by the first margin characteristic.

13. The system of claim 1 , wherein defining the first contour of the data signal eye includes comparing the serial data output with expected values over the first number of bit periods; and wherein defining the second contour of the data signal eye includes comparing the serial data output with expected values over the second number of bit periods.

14. The system of claim 1 , wherein the system is implemented as part of a storage device.

15. A method for margin determination, the method comprising:

repeatedly sampling a received serial data input by a sampling latch circuit to yield a corresponding serial data output;

defining a first contour of a data signal eye corresponding to the serial data output over a first number of bit periods;

determining a first margin characteristic based upon the first contour;

defining a second contour of a data signal eye corresponding to the serial data output over a second number of bit periods;

determining a second margin characteristic based upon the second contour;

using a margin normalization circuit operable to calculate a normalized value based upon a combination of the first margin characteristic and the second margin characteristic; and

transmitting an output to a recipient device that is indicative of the normalized value.

16. The method of claim 15 , the method further comprising:

determining a target margin value;

multiplying the target margin value by the normalized value to yield a margin output;

formatting the margin output to yield a formatted margin output; and

transmitting the formatted margin output to the recipient device as part of the output.

17. The method of claim 15 , the method further comprising:

defining a third contour of a data signal eye corresponding to the serial data output over a third number of bit periods, wherein the third number of bit periods is less than both the first number of bit periods and the second number of bit periods;

determining a target margin characteristic based upon the third contour.

18. The method of claim 17 , wherein the target margin characteristic is a maximum value of the third contour, and wherein the method further comprises:

transmitting the maximum value of the third contour to the requesting device.

19. The method of claim 16 , wherein the received serial data input is received from the recipient device via a bus.

20. The method of claim 19 , wherein the bus is a PCie™ bus.

21. The method of claim 15 , wherein the second number of bit periods is at least ten times greater than the first number of bit periods.

22. A computer system, the system comprising:

a first electronic device and a second electronic device communicably coupled by a bus;

wherein the first electronic device includes:

a first sampling latch operable to: sample a first received serial data input from the second electronic device via the bus, and provide a corresponding first serial data output;

a first duration margin determination circuit operable to: define a first contour of a first data signal eye corresponding to the first serial data output over a first number of bit periods, and determine a first margin characteristic based upon the first contour of the first data signal eye;

a second duration margin determination circuit operable to: define a second contour of the first data signal eye corresponding to the first serial data output over a second number of bit periods, and determine a second margin characteristic based upon the second contour of the first data signal eye;

a first margin normalization circuit operable to calculate a first normalized value based upon a combination of the first margin characteristic and the second margin characteristic; and

a first transmission circuit operable to transmit a first output indicative of the first normalized value to a requesting device;

and wherein the second electronic device includes:

a second sampling latch operable to: sample a second received serial data input from the first electronic device via the bus, and provide a corresponding second serial data output;

a third duration margin determination circuit operable to: define a first contour of a second data signal eye corresponding to the second serial data output over a third number of bit periods, and determine a third margin characteristic based upon the first contour of the second data signal eye;

a second duration margin determination circuit operable to: define a second contour of the second data signal eye corresponding to the second serial data output over a fourth number of bit periods, and determine a fourth margin characteristic based upon the second contour of the second data signal eye;

a second margin normalization circuit operable to calculate a second normalized value based upon a combination of the third margin characteristic and the fourth margin characteristic; and

a second transmission circuit operable to transmit a second output indicative of the second normalized value to the requesting device.

23. The system of claim 22 , wherein:

the first electronic device further includes:

a first target margin calculation circuit operable to determine a first target margin value; and

wherein the first margin normalization circuit is further operable to multiply the first target margin value by the first normalized value to yield a first margin output; and

a first data output circuit operable to communicate a first margin value derived from the first margin output to the second electronic device over the bus; and

the second electronic device further includes:

a second target margin calculation circuit operable to determine a second target margin value; and

wherein the second margin normalization circuit is further operable to multiply the second target margin value by the second normalized value to yield a second margin output; and

a second data output circuit operable to communicate a second margin value derived from the second margin output to the first electronic device over the bus.

24. The system of claim 22 , wherein the second number of bit periods is at least ten times greater than the first number of bit periods; and wherein the fourth number of bit periods is at least ten times greater than the third number of bit periods.