Visible to Intel only — GUID: gqq1495493564329
Ixiasoft
Visible to Intel only — GUID: gqq1495493564329
Ixiasoft
6.2. RX MAC Interface to User Logic
The Low Latency 100G Ethernet Intel FPGA IP core RX datapath employs the Avalon® streaming interface protocol. The Avalon® streaming interface protocol is a synchronous point-to-point, unidirectional interface that connects the producer of a data stream (source) to a consumer of data (sink). The key properties of this interface include:
- Start of packet (SOP) and end of packet (EOP) signals delimit frame transfers.
- The SOP must always be in the MSB, simplifying the interpretation and processing of data you receive on this interface.
- A valid signal qualifies signals from source to sink.
The RX MAC acts as a source and the client acts as a sink in the receive direction.
Name |
Direction |
Description |
---|---|---|
clk_rxmac | Output | The RX clock for the IP core is clk_rxmac. The IP core recovers this clock from the incoming data. This clock is guaranteed stable when rx_pcs_ready is asserted. The frequency of this clock is 390.625 MHz. |
l8_rx_data[511:0] | Output |
RX data. Bit 511 is the MSB and bit 0 is the LSB. Bytes are read in the usual left to right order. The IP core reverses the byte order to meet the requirements of the Ethernet standard. |
l8_rx_empty[5:0] | Output |
Indicates the number of empty bytes on l8_rx_data[511:0] when l8_rx_endofpacket is asserted, starting from the least significant byte (LSB). |
l8_rx_startofpacket | Output |
When asserted, indicates the start of a packet. The packet starts on the MSB. |
l8_rx_endofpacket | Output |
When asserted, indicates the end of packet. In the case of an undersized packet, or in the case of a packet that is exactly 64 bytes long, l8_rx_startofpacket and l8_rx_endofpacket are asserted in the same clock cycle. |
l8_rx_error[5:0] | Output | Reports certain types of errors in the Ethernet frame whose contents are currently being transmitted on the client interface. This signal is valid in EOP cycles only. The individual bits report different types of errors:
|
l8_rx_valid | Output |
When asserted, indicates that RX data is valid. Only valid between the l8_rx_startofpacket and l8_rx_endofpacket signals. This signal might be deasserted between the assertion of l8_rx_startofpacket and l8_rx_endofpacket. |
l8_rxstatus_valid | Output | When asserted, indicates that l8_rxstatus_data is driving valid data. This signal behaves identically to the l8_rx_endofpacket signal. |
l8_rxstatus_data[39:0] | Output | Specifies information about the received frame. The following fields are defined:
|