Altera Corporation
2–159
October 2007
Stratix II GX Device Handbook, Volume 2
Stratix II GX Transceiver Architecture Overview
Compliance Pattern Transmission Support
PCI Express has an option to transmit a compliance pattern for testing
purposes. The compliance pattern must be transmitted with a negative
disparity. In PIPE mode, you set the negative disparity with the
tx_forcedispcompliance
port.
Asserting the
tx_forcedispcompliance
port sets the associated byte
in the
tx_datain
port to be encoded, by the 8B/10B encoder, to a
negative disparity. If a wider PLD interface is used, only the LSByte is
encoded with a negative disparity. The
tx_forcedispcompliance
port must be deasserted after the first byte of the compliance pattern is
clocked into the transceiver.
The compliance pattern generator is not part of the Stratix II GX
transceiver and must be designed using the PLD logic. However, you can
set the beginning of the disparity of the compliance pattern to negative by
asserting the
tx_forcedispcompliance
port.
NTFS Fast Recovery IP (NFRI)
The PCI-E specification fast training sequences (FTS) are used for bit and
byte synchronization to transition from L0s state to L0 (Stratix II GX P0s
to P0) power states. The PCI-E base specification states that the required
time period for this transaction be within 16 ns to 4 us. Currently, the
default PIPE ALT2GXB settings do not meet these requirements.
Therefore, Altera developed NTFS fast recovery IP (NFRI), a soft IP that
enables the receiver to transition from the P0s to the P0 state within 4 us.
The Quartus II software creates this NFRI soft IP when the
Enable fast
recovery mode
option is selected in the ALT2GXB MegaWizard Plug-In
Manager. This option is available from the Quartus II software
version 6.0, SP1.
FTS ordered sets are used by the receiver to detect exit from Electrical Idle
(EIdle) and align the receiver’s bit/symbol receiver circuitry to the
incoming data. If the FTS time period (4 us) expires prior to the receiver
obtaining alignment and deskew on all lanes, the receiver transitions to
the recovery state (the PCI Express [PIPE] ALT2GXB performs only word
alignment. The deskew operation should be done in the user logic).
Following the electrical idle condition, the Stratix II GX device requires
255 FTS sequences to recover valid data.
Содержание Stratix II GX
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