Altera POS-PHY Level 2 and 3 Compiler - Manual (Page 43)

Chapter 3: Functional Description 3–15
Parameters
© November 2009 Altera Corporation POS-PHY Level 2 and 3 Compiler User Guide
Preliminary
FIFO Buffer Size
The FIFO buffer size is automatically set to be as wide as the widest of the input and
the output port.
Each word in the FIFO buffer can only contain at most one packet. Where the FIFO
buffer width is N bytes, packets of 1 to N bytes in length occupy 1 FIFO buffer word.
So, a FIFO buffer of (M words × N bytes) can only hold M packets with a length of 1 to
N bytes.
Address & Packet Available Settings
The Atlantic interface always operates in direct (no addressing) mode.
POS-PHY Level 3 Interfaces
The POS-PHY level 3 interfaces can be multi- or single-channel. Table 3–5 shows the
multi-channel packet available mode options.
Table 3–6 shows the multi-channel packet available mode options.
1
‘B’ interfaces always operate in direct mode.
POS-PHY Level 2 Interfaces
The POS-PHY level 2 interfaces can be multi- or single-channel. Table 3–7 shows the
multi-channel packet available mode options.
Table 3–5. Multi-Channel Packet Available Mode Options (POS-PHY Level 3)
Option Description
Direct In the POS-PHY transmit direction the MegaCore function uses one dtpa
pin per supported channel. In the POS-PHY receive direction the MegaCore
function uses renb and rval to support all channels.
Polled In the POS-PHY transmit direction the MegaCore function uses tadr,
ptpa
, and stpa, to support all channels.
Polled (Ignore stpa) In the POS-PHY transmit direction the MegaCore function uses tadr and
ptpa to support all channels. For compatibility with some POS-PHY
interfaces that do not support the functionality of the stpa pin, the stpa
signal is ignored and removed from the MegaCore function.
Table 3–6. Single-Channel Packet Available Mode Options (POS-PHY Level 3)
Option Description
Direct In the POS-PHY transmit direction the MegaCore function uses one
dtpa
pin, and uses a tsx pin. In the POS-PHY receive direction the
MegaCore function uses renb and rval, and uses an rsx pin.
Direct (No Addressing) In the POS-PHY transmit direction the MegaCore function uses one
dtpa
pin, and does not use a tsx pin. In the POS-PHY receive direction
the MegaCore function uses renb and rval, and does not use an rsx
pin.