Altera POS-PHY Level 4 IP Core Manual de usuario descargar pdf (Pagina 57)

Chapter 4: Functional Description—Receiver 4–19

Error Flagging and Handling

December 2014 Altera Corporation POS-PHY Level 4 IP Core User Guide

Table 4–4 summarizes the errors.

Table 4–4. Atlantic Error Handling (Part 1 of 2)

Error Condition Response

Missing SOP

■ Packet is not open.

■ End of packet (EOP) without

preceding SOP.

■ Data belonging to unopened

packet is discarded.

■ When it detects a missing SOP error, the Atlantic

FIFO buffer error checker block asserts the

err_ry_msopN

flag.

■ Data following a missing SOP is ignored for that

port until an EOP is detected.

■ Drops data not preceded by a SOP (data is not

readable via the Atlantic interface).

Refer to “Missing SOP” on page 4–21.

Missing EOP

■ Multiple packets are open.

■ SOP without a preceding EOP.

■ Data subsequent to the

detection of multiple open

packets is discarded until an

EOP is detected.

■ Assert

err_ry_meopN

for one clock cycle. When

it detects a missing EOP error, the open packet is

closed by forcing an EOP into the buffer and

marking it with an error. When it is received on

the user Atlantic interface side, the

aN_arxerr

and

aN_arxeop

signals are asserted.

■ The

stat_ry_mp_erradr

signal contains the

address of the failing packet.

■ Subsequent data that is rejected until the EOP is

detected is not signaled by the

err_ry_meopN

signal.

Empty non-zero

■ The

aN_arxmty

inputs must

be zero whenever the

aN_arxeop

signal is not

asserted.

■ If a new packet with a non-

zero value for MTY is received

without an EOP, all

subsequent data associated

with that address is ignored

until an EOP associated with

that address is received.

■ When it detects the error, the open packet is

closed.

■ Assert

err_ry_meopN

for one clock cycle by

forcing an EOP into the buffer and marking it with

an error. When it is received on the transmit side,

the

aN_atxerr

and

aN_atxeop

signals are

asserted.

■ The signal

stat_ry_mp_erradr

contains the

address of the failing packet.

■ Subsequent data that is rejected until the EOP is

detected is not signaled by the

err_ry_meopN

signal.

■ If an EOP is forced, the

aN_atxerr

output signal

is asserted. Generally this signal can be ignored,

unless the

aN_atxeop

signal is also asserted.

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Altera POS-PHY Level 4 IP Core Manual de usuario Pagina 57

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