Altera POS-PHY Level 4 IP Core Manual do Utilizador descarregar pdf (Página 51)

Chapter 4: Functional Description—Receiver 4–13

Error Flagging and Handling

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

SPI-4.2 Protocol Errors

The receiver IP core decodes the control words from the incoming SPI-4.2 interface

and ensures that they follow the state machine shown in Fig. 6.2. Data Path State

Diagram of the SPI-4.2 Specification, and ensures that there are no other errors. Table 4–3

summarizes the SPI-4.2 protocol errors.

Table 4–3. SPI-4.2 Protocol Error Handling (Part 1 of 3) (Note 1), (2)

Error Condition Response

Protocol error

A transition on the receiver data path that does not follow

Fig. 6.2. Data Path State Diagram of the SPI-4.2

Specification.

■ Assert

err_rd_pr

for one clock

cycle.

Start-of-packet spacing

violation (SOP8)

The SPI-4.2 specification states that SOP control words

should not be less than 8 cycles apart.

■ Asserts

err_rd_sop8

for one

clock cycle. When this happens,

the data is not affected.

Start of burst error

(SOB)

Data or training data is received without a payload control

word.

■ Assert

err_rd_sob

for one

cycle.

■ Data is dropped until a proper

payload control word is received.

Training pattern error

Training pattern errors (

err_rd_tp

) occur when one of the

following conditions occur:

■ Training control portion is too short.

■ Training control portion is too long.

■ Training data portion is too short.

■ Training data portion is too long.

■ Training control word is followed by something other

than another training control word or training data

word.

■ Malformed data bus during a data or control word.

■ Missing

IDLE

before training pattern begins. (The

IDLE

can be an EOP).

■ Assert

err_rd_tp

at the end of

the training pattern.

■ Channel aligner may not lock.

■ Some training pattern errors may

result in successive assertions of

the

err_rd_tp

interrupt (for

example, Training Control portion

> 10 cycles).

8N boundary error

(8N_ERR)

A burst that is neither a multiple of 16 bytes, nor an EOP.

■ Assert

err_rd_eightn

for one

clock cycle.

■ Packet is marked as errored.

■ Consider error as a missing EOP.

■ Cleanly terminate packet

internally as an EOP-Abort. (3)

■ Process subsequent bursts as

per missing SOP.

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