
Chapter 4: Functional Description 4–67
Error Detection and Management
August 2014 Altera Corporation RapidIO MegaCore Function
User Guide
■ Illegal Transaction Decode is declared when a request packet for a supported
transaction is too short or if it contains illegal values in some of its fields such as in
these examples:
■ Request packet with
priority
=
3
.
■
NWRITE
or
NWRITE_R
request packets without payload.
■
NWRITE
or
NWRITE_R
request packets with reserved
wrsize
and
wdptr
combination.
■
NWRITE
,
NWRITE_R
,
SWRITE
, or
NREAD
request packets for which the address does
not match any enabled address mapping window.
■
NREAD
request packet with
payload
.
■
NREAD
request with
rdsize
that is not an integral number of transfers on all byte
lanes. (The Avalon-MM interface specification requires that all byte lanes be
enabled for read transfers. Therefore, Read Avalon-MM master modules do not
have a byteenable signal).
■ Payload size does not match the size indicated by the
rdsize
or
wrsize
and
wdptr
fields.
Response Packets with ERROR Status
An
ERROR
response packet is sent for
NREAD
and
NWRITE_R
and Type 5
ATOMIC
request
packets that cause an
Illegal Transaction Decode
error to be declared. An
ERROR
response packet is also sent for
NREAD
requests if the
io_m_rd_readerror
input signal
is asserted through the final cycle of the Avalon-MM read transfer.
Avalon-ST Pass-Through Interface
Packets with valid CRCs that are not recognized as being targeted to one of the
implemented Logical layer modules are passed to the Avalon-ST pass-through
interface for processing by user logic.
The RapidIO IP core also provides hooks for user logic to report any error detected by
a user-implemented Logical layer module attached to the Avalon-ST pass-through
interface.
The transmit side of the Avalon-ST pass-through interface provides the
gen_tx_error
input signal that behaves essentially the same way as the
atxerr
input signal
described in “Physical Layer Receive Buffer” on page 4–14.
If Enable Avalon-ST pass-through interface is enabled and at least one of the Data
Messages options Source Operation and Destination Operation is turned on in the
RapidIO parameter editor, the message passing error management input ports in
Table 5–21 are added to the IP core to enable integrated error management.
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