Altera POS-PHY Level 2 and 3 Compiler - Manual (Page 41)

Chapter 3: Functional Description 3–13
Parameters
© November 2009 Altera Corporation POS-PHY Level 2 and 3 Compiler User Guide
Preliminary
Atlantic Interface FIFO Buffer Settings
For the Atlantic master source, the dav signal is an input. The slave indicates to the
master that it has space by asserting dav. The master then tries to fill the slave FIFO
buffer.
Figure 3–11 shows the behavior of the dav signal. FIFO burst is not applicable.
FIFO buffer remote burst—when the slave deasserts dav, the master can transfer up to
FIFO buffer remote burst more bytes of data before stopping.
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 output.
When operating in direct status
mode, this is indicated by
deasserting the DTPA outputs.
—
PHY
Receive
(Source) When there are more than FIFO buffer
threshold bytes in any of its FIFO buffers (1
FIFO buffer per channel), the interface
indicates this on a per channel basis to the
link receive interface.
When operating in polled mode, this is
indicated by asserting the PRPA output.
When operating in direct status mode, this
is indicated by asserting the DRPA outputs.
When there are less than or equal to
FIFO buffer burst bytes in any of its
FIFO buffers (1 FIFO buffer per
channel), the interface indicates
this on a per channel basis to the
link receive interface.
When operating in polled mode,
this is indicated by deasserting the
PRPA output.
When operating in direct status
mode, this is indicated by
deasserting the DRPA outputs.
—
Table 3–4. POS-PHY Level 2 FIFO Buffer Settings (Part 2 of 2)
Interface
(Direction) FIFO Threshold FIFO Burst FIFO Remote Burst
Figure 3–11. Behavior of the dav Signal as an Input to the Atlantic Master Source (Note 1)
Note to Figure 3–11 :
(1) The slave asserts dav high for two reasons: it has passed its threshold, or an EOP has occurred.
Slave has no space
dav
1
0
Slave has space