Achronix Speedster22i 10G/40G/100G Ethernet - Manual (Page 14)

14 UG029, September 6, 2013
000110: ff_rx_data[47:0] is valid
000111: ff_rx_data[55:0] is valid
001000: ff_rx_data[63:0] is valid (40/100G only)
001001: ff_rx_data[71:0] is valid (40/100G only)
.....
.....
011110: ff_rx_data[239:0] is valid (40/100G only)
011111: ff_rx_data[247:0] is valid (40/100G only)
100000: ff_rx_data[255:0] is valid (100G only)
100001: ff_rx_data[263:0] is valid (100G only)
.....
.....
111110: ff_rx_data[495:0] is valid (100G only)
111111: ff_rx_data[503:0] is valid (100G only)
ff_rx_err[11:0] Out
Receive Frame Error per segment. Asserted with the frame's final
data word to indicate that an error was detected when receiving the
frame. The type of error is coded on the status word
ff_rx_err_stat[23:0].
ff_rx_rdy[11:0] In
Receive Ready per segment. The ff_rx_rdy signal is asserted high
to indicate to the Receive FIFO that it may transmit ff_rx_data.
Deasserting the ff_rx_rdy signal allows the user to pause the
reception of ff_rx_data, but the Receive FIFO Almost Full flag,
ff_rx_afull, must be monitored to prevent the Receive FIFO from
overflowing, resulting is a loss of data.
ff_rx_afull[11:0] Out
Receive FIFO Almost Full flag per segment. The ff_rx_afull flag is
asserted high when there are 15 or fewer empty locations
remaining in the Receive FIFO.
ff_rx_vlan
[(12*2)-1:0]
Out
Receive Frame VLAN Indication per segment. Asserted with the
frame’s final data word to indicate that the current frame
implements a VLAN Tag (bit 0 asserted) or a Stacked VLAN Tag
(bit 1 asserted).
ff_rx_err_stat[23:0] Out
Receive Frame Status and Error Indications. A status word is
available for each received frame with the final word (ff_rx_eop =
1). The receive frame status ff_rx_err_stat[23:0] can be
mapped to any segment of FIFO group 0 (10G: SEG0-3, 40G:
SEG0, 100G: SEG0).
_stat[0]: Set to 1 when the current frame has an invalid length,
i.e. less than 64 octets or more than the maximum value defined in
register FRM_LENGTH, or a mismatch between the payload
received and the payload length given within the frame was
detected.
_stat[1]: Set to 1 to indicate that the current frame was received
with a CRC-32 error.
_stat[2]: Set to 1 to indicate that the current frame was received
with a wrong or unexpected code during frame reception reported
by the reconciliation sub-layer function.
_stat[3]: Set to 1 to indicate that the current frame was truncated
because of a FIFO exception (Overflow).
_stat[4]: Set to 1 to indicate that a Sequence Error (Local or
Remote) was received from the PHY device during frame reception.
_stat[5]: Set to 1 to indicate that the current Frame implements a
Stacked VLAN Tag.
_stat[6]: Set to 1 to indicate that the current frame was received
with an Error control character on the XL/CGMII interface.
_stat[7]: Set to 1 to indicate that the current Frame implements a
VLAN Tag.
_stat[23:8]: Payload length of the frame. This is a copy of the
length/type field as it is found within the frame. For VLAN frames it
is a copy of the length/type field following the 4-octet VLAN tag.
ff_rx_ts[31:0] Out Receive Timestamp Value. Time when the MAC detected the