
4–14 Chapter 4: Functional Description—Receiver
Error Flagging and Handling
POS-PHY Level 4 IP Core User Guide December 2014 Altera Corporation
Reserved control word
Reserved control words:
■ Reserved control word 0 (
RSV0
)
= CTL and
DAT[15:12] == 4’b0101
■ Reserved control word 1 (
RSV1
) =
CTL and DAT[15:12] == 4’b0011
■ Extension control (
EXT
)
=
CTL and DAT[15:12] == 4’b0001
■ End of control word extension (
EOE
)
= CTL and
DAT[15:12] == 4’b0111
Reserved control words are identified by the assertion of
the
stat_rd_rsv_cw
signal, which pulses high for a
single
rdint_clk
clock cycle when a reserved control
word is detected.The payload following the reserved
control word is not written into any buffer.
■ Ignore reserved control words.
■ Assert the
stat_rd_rsv_cw
for
notification purposes.
■ The payload following the
reserved control word is not
written into the FIFO buffer.
Single DIP-4 error
As part of the SPI-4.2 protocol control word content, the 4-
bit diagonal interleaved parity (DIP-4) is computed over the
current control word and preceding data. A DIP-4 error
occurs when the DIP-4 calculated over the
rdat
line does
not match the DIP-4 value in the control word.
■ Assert
err_rd_dip4
for one
clock cycle.
■ Optionally mark some or all open
packets with an Atlantic error.
(Including packets with DIP-4
error at SOP). The packets have
aN_arxerr
asserted (high).
Refer to “DIP-4 Marking” on
page 4–16.
Table 4–3. SPI-4.2 Protocol Error Handling (Part 2 of 3) (Note 1), (2)
Error Condition Response
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