Altera POS-PHY Level 2 and 3 Compiler - Manual (Page 40)

3–12 Chapter 3: Functional Description
Parameters
POS-PHY Level 2 and 3 Compiler User Guide © November 2009 Altera Corporation
Preliminary
Table 3–4. POS-PHY Level 2 FIFO Buffer Settings (Part 1 of 2)
Interface
(Direction) FIFO Threshold FIFO Burst FIFO Remote Burst
Link
Transmit
(Source) When each FIFO buffer fills to above the
FIFO buffer threshold level, or contains a
packet or packet fragment with an EOP, it
triggers its not empty flag. The interface
then tries to empty each of the FIFO buffers
containing data, as soon as it detects the
PHY transmit interface has indicated it has
space.
When operating in polled mode, this is
detected using the PTPA and STPA inputs.
When operating in direct status mode, this
is detected using the DTPA inputs.
Indicates the maximum number of
bytes the interface transfers in each
FIFO buffer burst.
In MPHY mode, at the end of each
FIFO buffer burst the MegaCore
function re-arbitrates for a new
channel in a round-robin fashion.
Set FIFO buffer burst <= FIFO buffer
threshold.
Not applicable in SPHY mode.
When the interface is in
the process of
transferring data and the
PHY transmit interface
indicates it is almost full,
the link transmit interface
transfers up to FIFO
buffer remote burst more
bytes before stopping.
When operating in polled
mode, this is detected
using the PTPA and
STPA inputs.
When operating in direct
status mode, this is
detected using the DTPA
inputs.
Link
Receive
(Sink) When there is more than or equal to FIFO
buffer threshold spaces for bytes in any of
its FIFO buffers (1 FIFO buffer per channel),
the internal FIFO buffer full flag is
deasserted. This allows the interface to
start transferring data, as soon as it detects
the PHY receive interface has indicated it
has data.
When operating in polled mode, this is
detected using the PRPA input.
When operating in direct status mode, this
is detected using the DRPA inputs.
Indicates the maximum number of
bytes the interface transfers in each
FIFO buffer burst. When there is
less than FIFO buffer burst spaces
in the FIFO buffer, the internal FIFO
buffer full flag is asserted.
In MPHY mode, at the end of each
FIFO buffer burst the MegaCore
function re-arbitrates for a new
channel in a round-robin fashion.
Set FIFO buffer burst <= FIFO buffer
threshold.
In SPHY mode, this should be set
to the minimum value allowed.
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