Packet Delayer

ENTITY MFB_PACKET_DELAYER IS

Incoming packets with Timestamps [ns] are stored in the RX FIFO. From there each packet is read when the Stored time value reaches the packet’s Timestamp value. There are 2 Timestamp formats that are currently supported (see the TS_FORMAT generic). The packets read from the RX FIFO are stored in the TX FIFO.

Generics

Generic

Type

Default

Description

MFB_REGIONS

natural

1

Number of Regions within a data word, must be power of 2.

MFB_REGION_SIZE

natural

8

Region size (in Blocks).

MFB_BLOCK_SIZE

natural

8

Block size (in Items), must be 8.

MFB_ITEM_WIDTH

natural

8

Item width (in bits), must be 8.

MFB_META_WIDTH

natural

0

Metadata width (in bits).

TS_WIDTH

natural

48

Width of Timestamps (in bits).

TS_FORMAT

natural

0

Format of Timestamps. Options:

  • 0 number of NS between individual packets,

  • 1 number of NS from RESET.

FIFO_DEPTH

natural

2048

Number of Items in the Input MFB_FIFOX (main buffer).

FIFO_AF_OFFSET

natural

1000

Almost Full Offset of the Input MFB_FIFOX. Pauses the appropriate DMA channel when the amount of stored Items reaches this value.

FIFO_AE_OFFSET

natural

1000

Almost Empty Offset of the input MFB_FIFOX. Unpauses (resumes) the appropriate DMA channel when the amount of stored Items drops under this value.

DEVICE

string

“STRATIX10”

FPGA device name: ULTRASCALE, STRATIX10, AGILEX, …

Ports

Port

Type

Mode

Description

=====

Clock and Reset

=====

=====

CLK

std_logic

in

RESET

std_logic

in

TIME_RESET

std_logic

in

Reset time accumulation (applies only when TS_FORMAT=1). Time counter is reset with the next first SOF.

CURRENT_TIME

std_logic_vector(64-1 downto 0)

in

A 64-bit value representing Time, which is used to decide whether a packet’s Timestamp is OK and can be transmitted or not. It can be a precise time from the TSU, a value from a simple incrementing counter, or anything in between. The quality of the time source affects the precision of the packet’s transmission but not the component’s functionality.

PAUSE_REQUEST

std_logic

out

Used to pause incomming traffic when the buffer is Almost Full.

=====

RX inf

=====

=====

RX_MFB_DATA

std_logic_vector(MFB_REGIONS*MFB_REGION_SIZE*MFB_BLOCK_SIZE*MFB_ITEM_WIDTH-1 downto 0)

in

RX_MFB_META

std_logic_vector(MFB_REGIONS*MFB_META_WIDTH-1 downto 0)

in

Valid with SOF.

RX_MFB_TS

std_logic_vector(MFB_REGIONS*TS_WIDTH-1 downto 0)

in

Timestamp valid with each SOF.

RX_MFB_SOF_POS

std_logic_vector(MFB_REGIONS*max(1,log2(MFB_REGION_SIZE))-1 downto 0)

in

RX_MFB_EOF_POS

std_logic_vector(MFB_REGIONS*max(1,log2(MFB_REGION_SIZE*MFB_BLOCK_SIZE))-1 downto 0)

in

RX_MFB_SOF

std_logic_vector(MFB_REGIONS-1 downto 0)

in

RX_MFB_EOF

std_logic_vector(MFB_REGIONS-1 downto 0)

in

RX_MFB_SRC_RDY

std_logic

in

RX_MFB_DST_RDY

std_logic

out

=====

TX inf

=====

=====

TX_MFB_DATA

std_logic_vector(MFB_REGIONS*MFB_REGION_SIZE*MFB_BLOCK_SIZE*MFB_ITEM_WIDTH-1 downto 0)

out

TX_MFB_META

std_logic_vector(MFB_REGIONS*MFB_META_WIDTH-1 downto 0)

out

Valid with SOF.

TX_MFB_SOF_POS

std_logic_vector(MFB_REGIONS*max(1,log2(MFB_REGION_SIZE))-1 downto 0)

out

TX_MFB_EOF_POS

std_logic_vector(MFB_REGIONS*max(1,log2(MFB_REGION_SIZE*MFB_BLOCK_SIZE))-1 downto 0)

out

TX_MFB_SOF

std_logic_vector(MFB_REGIONS-1 downto 0)

out

TX_MFB_EOF

std_logic_vector(MFB_REGIONS-1 downto 0)

out

TX_MFB_SRC_RDY

std_logic

out

TX_MFB_DST_RDY

std_logic

in

Block diagram