Altera POS-PHY Level 2 and 3 Compiler - Manual (Page 39)

Chapter 3: Functional Description 3–11
Parameters
© November 2009 Altera Corporation POS-PHY Level 2 and 3 Compiler User Guide
Preliminary
Table 3–4 shows the effect of the FIFO buffer settings for POS-PHY level 2 interfaces.
PHY
Transmit
(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
interface indicates this on a per
channel basis to the link transmit
interface.
When operating in polled mode,
this is indicated by asserting PTPA
and STPA outputs.
When operating in direct status
mode, this is indicated by asserting
the DTPA outputs.
When there is less than FIFO
buffer burst spaces for bytes
in any of its FIFO buffers (1
FIFO buffer per channel), the
interface indicates this on a
per channel basis to the link
transmit interface.
When operating in polled
mode, this is indicated by
deasserting the PTPA and
STPA outputs.
When operating in direct
status mode, this is indicated
by deasserting the DTPA
outputs.
—
PHY
Receive
(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 with data, as
soon as it detects the link receive
interface has asserted low the
RENB input. 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.
In SPHY mode, this should
be set to the minimum value
allowed.
—
Table 3–3. POS-PHY Level 3 FIFO Buffer Settings (Part 2 of 2)
Interface
(Direction) FIFO Threshold FIFO Burst FIFO Remote Burst