Altera SerialLite III Streaming MegaCore Function - Manual (Page 36)

Table 4-4: Comparing Standard and Advanced Clocking Modes
Resource Standard Mode Advanced Mode Description
Source user
clocking
Core generated User provided If the PPM difference between the
generated and user clocks is not
acceptable, use the advanced
clocking mode.
MAC fPLL Uses one fPLL per
direction
Does not use fPLLs If the design uses many fPLLs and
clock crossing is an issue in the
user environment, use the
advanced clocking mode.
Transmission
overhead
1.1 x <input data rate> <Interlaken Overhead> x
<input data rate>
The advanced clocking mode
overhead is less than the standard
clocking mode overhead.
Streaming
variation
Pure streaming where the
output data appears
exactly as it was input
Output streaming data is
accompanied by
numerous empty clock
cycles
If empty cycles (where no valid
data is present) at the output are
intolerable, use pure streaming
(standard clocking mode).
Alternatively, create your own sink
interface to remove the empty
cycles.
Sink interface Fixed You can include your
own logic or FIFO to
receive the output data
Advanced Clocking Mode on
page 4-13
Standard Clocking Mode
In the standard clocking mode, the SerialLite III Streaming IP core operates in a pure streaming manner,
exactly replicating the source input data at the sink end. The SerialLite III Streaming IP core generates the
user clock at both the source and sink to drive the user interface.
In this mode, you initially specify the user clock frequency through the SerialLite III Streaming parameter
editor. The Quartus II software then automatically calculates the reference clock coming from the Native
PHY or Interlaken PHY IP core and the two clock outputs from the fPLL in the clock generator module.
After the calculation, the Quartus II software provides a list of transceiver reference clock values for you to
select. Depending on the clock constraints, the generated value for the user clock should be very close, if
not identical, to the user clock frequency that you specify. The Quartus II software shows the generated
user clock value as well as transceiver reference clock values.
4-12 Standard Clocking Mode
UG-01126
2015.05.04
Altera Corporation SerialLite III Streaming IP Core Functional Description
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