Altera POS-PHY Level 4 IP Core - Manual (Page 84)

5–14 Chapter 5: Functional Description—Transmitter
Error Flagging and Handling
POS-PHY Level 4 IP Core User Guide December 2014 Altera Corporation
Table 5–2 summarizes the SPI-4.2 protocol errors.
Atlantic Interface Error Detection and Handling
When the Atlantic error checking parameter is turned on, a filtering block—the
Atlantic FIFO buffer error checker—is instantiated at the write side of the FIFO buffer
to ensure that only valid packets are written into memory.
The Atlantic FIFO buffer error checker block checks for missing SOP and EOP
markers, for each port. If these markers are found to be missing, their respective
err_aN_msopN
and err_aN_meopN signals are asserted and the packet is corrected.
These signals remain high for one aN_atxclk cycle. These error conditions do not
correlate directly—in terms of latency—to the data coming out of the FIFO buffer.
When a missing SOP error is detected, the Atlantic FIFO error checker block asserts
the err_aN_msopN flag and filters the burst. Data following a missing SOP is ignored
for that port until a SOP is detected.
Table 5–2. SPI-4.2 Protocol Error Handling
Error Condition Response
Single DIP-2 or frame error has been
detected
Assuming the bad_level input is greater
than 1 (ctl_ts_sync_bad_theshold)
Bit error on bus
■ When stat_ts_sync is asserted,
assert err_ts_dip2.
■ stat_ts_sync remains asserted
(high).
■ Transmit output data (TDAT) is
unaffected.
■ For pessimistic mode, the received
calendar status is ignored, the status
is not forwarded to the user logic, and
the transmit scheduler is not updated
with new credits.
■ For optimistic mode, no action is
taken. An incorrect status value may
be extracted and passed on to the
scheduler.
Multiple consecutive DIP-2 or frame
errors when sync is detected
Causes the bad_level counter to go over
the bad level threshold
(ctl_ts_sync_bad_theshold)
■ Bit errors on bus
■ Incorrect status edge
■ Calendar multiplier and
Maximum calendar length
values do not match the far-end
values
■ Receiver is sending incorrect
calendar multiplier or calendar
length values
■ Receiver sending corrupted
status frames
■ When stat_ts_sync is asserted, the
scheduler ignores a value of 11.
■ When stat_ts_sync is not asserted,
the state machine returns to the
disabled state and waits for the next
framing pattern.
■ All credits are revoked.
■ Data stops transmitting on the nearest
burst unit size boundary or EOP.
■ Training patterns are sent
continuously.
■ The data in the buffer is untouched.
■ Once the status channel regains sync,
the transmitter restarts, and packet
transfers resume from where they left
off (that is, continue open packets).