2–52
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Receiver Modules
This feature is only available in the PIPE mode and you enable it by
setting the
tx_forceelecidle
and
tx_detectrxloopback
ports to
1’b1. You must set the
powerdn
port to 2’b10 to place the transmitter in
the PCI-Express P1 power-down state. The results of the receiver detect is
encoded on the
pipestatus
port.
PCI Express Electrical Idle
The Stratix II GX transmitter buffer supports PCI Express Electrical Idle
(or individual transmitter tri-state). This feature is only active in the PIPE
mode. The
tx_forceelecidle
port puts the transmitter buffer in
Electrical Idle mode. This port is available in all PCI Express power-down
modes and has a specific use in each mode.
Table 2–10
shows the usage in
each power mode.
Receiver
Modules
This section describes the Stratix II GX transceiver’s receiver path. This
section describes the following modules:
■
Receiver buffer
■
Receiver PLL
■
Clock recovery unit
■
Deserializer
■
Word aligner
■
Channel aligner (deskew)
■
Rate matcher
■
8B/10B decoder
■
Byte deserializer
■
Byte Ordering
■
Receiver phase compensation FIFO buffer
Table 2–10. Power Mode Usage
Power Mode
Usage
P0
tx_forceelecidle
must be asserted. If this signal is
deasserted, it indicates that there is valid data.
P1
tx_forceelecidle
must be asserted.
P2
When deasserted, the beacon signal must be transmitted. Refer
to
“PCI Express (PIPE) Mode” on page 2–150
.