Achronix Speedster22i 10G/40G/100G Ethernet - Manual (Page 15)

UG029, September 6, 2013 15
SFD of the frame.
Valid with ff_rx_sop. The receive timestamp
ff_rx_ts[31:0] can be mapped to any segment of FIFO
group 0 (10G: SEG0-3, 40G: SEG0, 100G: SEG0).
ff_rx_preamble_val Out
Receive Frame Preamble Valid Indication. Asserted (set to
1) to indicate that a valid preamble is available on pin
ff_rx_preamble[55:0].
Note: Since the signal ff_rx_preamble_val is not a
pulse, the application should sample
ff_rx_preamble[55:0] when ff_rx_sop is set to 1.
ff_rx_preamble[55:0] Out
Receive Frame Preamble. 56-Bit preamble of the current
frame, valid when ff_rx_preamble_val is set to 1. The
receive frame preamble ff_rx_preamble[55:0] can be
mapped to any segment of FIFO group 0 (10G: SEG0-3,
40G: SEG0, 100G: SEG0).
Transmit FIFO Interface
Table 3 – Transmit FIFO Interface (all synchronous to ff_tx_clk[2:0])
Signal Name Mode Description
ff_tx_data
[767:0]
In
Transmit Data. Refer to the ‘Fabic FIFO Interface’ for the
details of how to map this 768-bit bus to the individual
10/40/100G channels.
ff_tx_wren[11:0] In
Transmit Data Write Enable per segment. Asserted by the
Transmit application to write data into the MAC Core FIFO.
ff_tx_sop[11:0] In
Transmit Start of Frame per segment. Set to 1 when the
first data word of a frame is driven on ff_tx_data.
ff_tx_eop[11:0] In
Transmit End of Frame per segment. Set to 1 when the
final data word of a frame is driven on ff_tx_data.
ff_tx_mod
[(12*6)-1:0]
In
Transmit Word Modulo per segment. Indicates which
portion of the final frame word is valid:
Bit 543210
000000 : ff_tx_data[63:0]/[255:0]/[511:0] is
valid (for 10/40/100G)
000001 : ff_tx_data[7:0] is valid
000010 : ff_tx_data[15:0] is valid
000011 : ff_tx_data[23:0] is valid
000100 : ff_tx_data[31:0] is valid
000101 : ff_tx_data[39:0] is valid
000110 : ff_tx_data[47:0] is valid
000111 : ff_tx_data[55:0] is valid
001000 : ff_tx_data[63:0] is valid (40/100G only)
001001: ff_tx_data[71:0] is valid (40/100G only)
.....
.....
011110: ff_tx_data[239:0] is valid (40/100G only)
011111: ff_tx_data[247:0] is valid (40/100G only)
100000: ff_tx_data[255:0] is valid (100G only)
100001: ff_tx_data[263:0] is valid (100G only)
.....
.....
111110: ff_tx_data[495:0] is valid (100G only)