Altera POS-PHY Level 2 and 3 Compiler - Manual (Page 54)

3–26 Chapter 3: Functional Description
Interface Signals
POS-PHY Level 2 and 3 Compiler User Guide © November 2009 Altera Corporation
Preliminary
Atlantic Interface
The Atlantic interface is a full-duplex synchronous point-to-point connection
protocol. The POS-PHY Level 2 and 3 Compiler supports data widths of 8, 16, 32, and
64 bits on the Atlantic interface.
f
For further information on the Atlantic interface, refer to the Atlantic Interface
Functional Specification.
Figure 3–17 shows the following two Atlantic interface control options (and all four
interface types):
■ Master source to slave sink
rval PHY to link Receive data valid signal. rval indicates the validity of the receive data signals. When
rval
is high, the receive signals (rdat, rsop, reop, rmod, rxprty and rerr)
are valid. When rval is low, all receive signals are invalid and must be disregarded.
rval
transitions low on a FIFO buffer empty condition or on an end of packet. Data is
not removed from the receive FIFO buffer while rval is deasserted. When deasserted,
rval
remains deasserted until current the PHY has been deselected. rval allows you
to monitor the selected PHY during a data transfer, while monitoring or polling other
PHYs is done using prpa or drpa[x]. The PHY-layer device tri-states rval when
renb
is deasserted. rval is also tri-stated when either the null-PHY address (1Fh),
or an address not matching the PHY-layer device address, is presented on the radr
signals when renb is sampled high (has been deasserted during the previous clock
cycle).
prpa (3) PHY to link Receive polled multi-PHY packet available signal. prpa indicates when data is available
in the polled receive FIFO buffer. When prpa is high, the receive FIFO buffer has at
least one end of packet or a predefined number of bytes to be read (the number of bytes
might be user programmable). prpa is low when the receive FIFO buffer fill level is
below the assertion threshold and the FIFO buffer contains no end of packet. prpa
allows to poll every PHY while transferring data from the selected PHY. prpa is driven
by a PHY-layer device when its address is polled on radr. A PHY-layer device tri-
states prpa when either the null-PHY address (1Fh), or an address not matching
available PHY-layer devices, is provided on radr.
drpa[x] (4) PHY to link Receive packet available direct status indication signals. These signals provides direct
status indication for the corresponding port (referred to by “x”). drpa[x] indicates
when data is available in the receive FIFO buffer. When drpa[x] is high, the receive
FIFO buffer has at least one end of packet or a predefined number of bytes to be read.
The number of bytes is user programmable. drpa[x] is low when the receive FIFO
buffer fill level is below the assertion threshold and the FIFO buffer contains no end of
packet.
rfclk Link to PHY Receive FIFO buffer write clock. rfclk is used to synchronize data transfer
transactions from the link-layer device to the PHY-layer device. rfclk can cycle at a
any rate from 25 MHz up to 50 MHz.
Notes to Table 3–12 :
(1) The 8-bit mode is an Altera extension to the POS-PHY Level 2 specification.
(2) Not present in 8-bit mode.
(3) Packet-level mode only.
(4) Byte-level mode only.
Table 3–12. POS-PHY Level 2 Receive Interface (Part 3 of 3)
Signal Direction Description