MPC8560 datasheet(70/108 Pages) FREESCALE

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MPC8560 Integrated Processor Hardware Specifications, Rev. 3.1

Freescale Semiconductor

RapidIO

eye pattern to change from one that complies with the RapidIO receive mask to one that does not comply with the

mask. The data carried by any given data signal in the interface may not be correlated with the data carried by any

other data signal in the interface. The zero-crossings of the clock associated with a data signal shall be used as the

timing reference for aligning the multiple recordings of the data signal when the recordings are overlaid.

While the method used to make the recordings and overlay them to form the eye pattern is not specified, the method

used shall be demonstrably equivalent to the following method. The signal under test is repeatedly recorded with a

digital oscilloscope in infinite persistence mode. Each recording is triggered by a zero-crossing of the clock

associated with the data signal under test. Roughly half of the recordings are triggered by positive-going clock

zero-crossings and roughly half are triggered by negative-going clock zero-crossings. Each recording is at least 1.9

UI in length (to ensure that at least one complete eye is formed) and begins 0.5 UI before the trigger point (0.5 UI

before the associated clock zero-crossing). Depending on the length of the individual recordings used to generate

the eye pattern, one or more complete eyes will be formed. Regardless of the number of eyes, the eye whose center

is immediately to the right of the trigger point is the eye used for compliance testing.

An example of an eye pattern generated using the above method with recordings 3 UI in length is shown in

Figure 47. In this example, there is no skew between the signal under test and the associated clock used to trigger

the recordings. If skew was present, the eye pattern would be shifted to the left or right relative to the oscilloscope

trigger point.

Figure 47. Example Receiver Input Eye Pattern

Figure 48 shows the definitions of the data to clock static skew parameter tSKEW,PAIR and the data valid window

parameter DV. The data and frame bits are those that are associated with the clock. The figure applies for all

zero-crossings of the clock. All of the signals are differential signals. VD represents VOD for the transmitter and VID

for the receiver. The center of the eye is defined as the midpoint of the region in which the magnitude of the signal

voltage is greater than or equal to the minimum DV voltage.

–

0.5 UI

1.0 UI

Oscilloscope

(Recording)

Trigger Point

Eye Pattern

Eye Used for

Compliance

Testing

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