Table 1062. Nar Transmit Operations - STMicroelectronics SPC572L series Reference Manual

RM0400
65.5.2.1 Reset
During reset all internal resources and queues are reset and all output ports are disabled.
All inputs are ignored. Upon exiting reset mode, the NAR is in a fully disabled state.
65.5.2.2 Disabled
In the disabled state, all message traffic is ignored, and all output ports are disabled. The
NAR is disabled if and only if the NAR enable bit of the NAR control register is not set and
the Aurora Link is inactive.
65.5.2.3 Suppressed
The suppressed state differs from the disabled state in that the NAR is on. The NAR pulls
out any messages that come up at the clients, keeping the Message Start-End Out (MSEO)
bits (so that it can keep track of message boundaries) and discarding the rest.
In the suppressed state, the NAR is waiting for a trigger to begin normal operation. Once
that trigger is received, the NAR begins queueing messages that started after the trigger
arrived. Incomplete messages that were in transit to the NAR when the trigger arrived are
discarded. The NAR can be put into suppressed mode by enabling one of the global
suppress states.
65.5.2.4 Trace disable
In trace disable mode, the NAR is powered up but all client-trace is disabled, and no
messages are pulled. This mode is also useful for port initialization (to prevent any activity
from occurring before the outputs are ready) or for debug/trace-buffer mode, to ensure that,
during data retrieval, the NARs queues are stable.
The NAR goes into trace disable (communication-disable) mode when the NAR-enable and
NAR communication-disable bits are set or when the HBDP channel is active while the
NAR-enable bit is not set.
65.5.2.5 NAR transmit
This is the standard operational mode of the NAR when it is transferring Nexus messages
from multiple clients to one or two enabled output port(s). The NAR performs four main
operations as described in this table on the incoming messages before transmitting to one
of the output ports.
Operation
NAR accepts data from each client based on the status of the client receive queue status.
The maximum data rate is 8 × 32-bit data words (where 8 is the number of Nexus message
Data reception
beats in a full entry and 32 is the number of bits in the Nexus word) per cycle per client.
MSEO bits of incoming data are monitored to identify end-of-message boundaries.
Active receive queue unloads into main queue(s), 8 × 32 bits per cycle (where 8 is the
number of Nexus message beats in a full entry and 32 is the number of bits in the Nexus
Input Arbitration
word). If end-of-message detected, new active receive queue is determined based on client
request level or round-robin algorithm.

Table 1062. NAR transmit operations

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Nexus Aurora Router (NAR)
Description
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