Curtiss-Wright FHF5-PC4MWB04-00, Hardware Reference Manual

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REGISTERS
Copyright 2017 6-5 FibreXtreme Hardware Reference
6.4.4 Link Control (LINK_CTL)
– Offset 0x08
Field Description Access Reset
Value
0 Allow Remote Transmitter
– Set to ‘1’ to enable the
remote transmitter to send link data. Set to ‘0’ to
request the remote transmitter to stop sending link
data. This flow control request will be ignored if the
remote end is configured to ignore flow control. This
signal is typically set to a '1' for most applications. It
exists to provide a mechanism to disable the remote
transmitter by forcing the transmitted flow control to a
STOP state.
R/W 0
1
CRC Enable
– Set to ‘1’ to enable the CRC
checking/generation of link data. Set to ‘0’ to disable
CRC checking/generation.
NOTE : CRC should be used in almost all applications.
It offers excellent coverage of data errors and has very
little impact on link throughput for maximum frame
sizes. The option of disabling CRC is only retained for
compatibility with older third-part devices. Both nodes
on the link (or all nodes in a loop configuration) should
be set to a common CRC mode or the resulting
mismatch will cause data errors and/or link errors.
R/W 0
2 Ignore Flow Control
– Set to ‘1’ to ignore flow control
from the remote end and continue transmitting when
the link is down. Set to ‘0’ to stop transmission when
the link goes down or the remote end is sending a
STOP ordered set back.
NOTE : In almost every application, flow control should
be enabled. Even if the application must sustain
maximum link throughput, it is better to drop the data at
the sending source should the system experience a
temporary overload condition. Some exotic conditions
could apply where flow control is not desirable, but they
require very careful system planning and should be
confirmed with Curtiss-Wright Controls, Inc. prior to
architectural finalization. One possible exception is for
applications that cannot utilize a duplex fiber optic link,
which means status information (link up and state of
flow control) is not available from the remote node. In
this circumstance, flow control should be disabled to
allow the transmitter to function without the receiver
connected normally.
R/W 0
3 Convert SYNC
– When ‘1,’ enables detection of a
received SYNC with DVALID from the link.
R/W 0
4 Stop on SYNC without DVALID
– If ‘1’ then stop the
Receive FIFO until software re-enables the transaction.
If ‘0’ the Receive FIFO is not stopped.
R/W 0
5 Stop on receiver error
– If ‘1’ then the Receive FIFO is
stopped when a CRC error or FIFO overflow is taken
out of its output. If ‘0’ then the Receive FIFO is not
stopped.
R/W 0