F-Tile Ethernet Intel® FPGA Hard IP User Guide

ID 683023
Date 12/19/2022
Public

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7.15.2. TX 2-Step Timestamp Interface

The timestamp interface signals are valid when i_tx_valid and i_tx_startofpacket signals are high. To initiate a timestamp request, the i_ptp_ts_req signal must be high. You also must specify a fingerprint value in the i_ptp_fp signal. The fingerprint values are re-usable once the IP core returns a packet with the timestamp.

Figure 56. Using the IEEE 1588 TX 2-Step Timestamp Interface The figure depicts transmission of two packets. The first packet contains a 2-step timestamp request with assigned FP1 fingerprint value.

When the IP core returns the timestamp for a packet with a 2-step timestamp request, it asserts the o_ptp_ets_valid signal to indicate that the o_ptp_ets and o_ptp_ets_fp signals contain the timestamp information. The o_ptp_ets contains the timestamp and the o_ptp_ets_fp signal indicates the specific packet the timestamp is for. The IP processes the timestamp requests in the order they were received.

Figure 57. 2-Step Timestamp: Receiving Packet with TimestampThe figure shows that the IP received the timestamp for packet FP1 and then sometime later, IP returns the timestamp for packet FP2.
Table 62.  Signals of the 2-Step TX Timestamp InterfaceThe timestamp is always in 1588 v2 format.

All interface signals are synchronous and clocked by the i_clk_tx clock.

Signal Name

Width

Description

i_ptp_ts_req

i_ptp_ts_req[1:0]

1 bit (10GE/25GE/50GE/100GE/200GE)

2 bits (400GE)

Request a 2-step timestamp signal for the current TX packet when Ethernet rate is 10GE/25GE/50GE/100GE/200GE/400GE.
  • For TX MAC Avalon ST client interface, i_ptp_ts_req[0] is valid only when both, i_tx_valid and i_tx_startofpacket signals, are equal to 1.
  • For TX MAC segmented client interface, i_ptp_ts_req[0] is valid only when i_tx_mac_valid is equal to 1 and i_tx_mac_inframe[7:0] contains the start of the packet (SOP).

    The i_ptp_ts_req[1] is valid only when i_tx_mac_valid is equal to 1 and i_tx_mac_inframe[15:8] contains the SOP.

i_ptp_fp[w],

where w represents timestamp fingerprint width

i_ptp_fp[w*2],

where w is 8-12

w bit (10GE/25GE/50GE/100GE/200GE)

(w*2) bits (400GE)

Fingerprint signal for current TX packet when Ethernet rate is 10GE/ 25GE/50GE/100GE/200GE/400GE.

Assigns an 8 bit fingerprint to a TX packet that is being transmitted so the returned TX egress timestamp can be identified with respective TX packet.

  • For TX MAC Avalon ST client interface, i_ptp_fp[(w-1):0] is valid only when both, i_tx_valid and i_tx_startofpacket signals, are equal to 1.
  • For TX MAC segmented client interface, i_ptp_fp[(w-1):0] is valid only when i_tx_mac_valid is equal to 1 and i_tx_mac_inframe[7:0] contains the start of the packet (SOP).

    The i_ptp_fp[w*2-1:w] is valid only when i_tx_mac_valid is equal to 1 and i_tx_mac_inframe[15:8] contains the SOP.

Used for both 2-step and 1-step PTP packets.

Intel recommends to use large range of fingerprints to avoid assigning same fingerprint to two currently processed TX packets.

o_ptp_ets_valid

o_ptp_ets_valid[1:0]

1 bit (10GE/25GE/50GE/100GE/200GE)

2 bits (400GE)

TX egress timestamp valid signal when Ethernet rate is 10GE/ 25GE/50GE/100GE/200GE/400GE.

o_ptp_ets[95:0]

o_ptp_ets[191:0]

96 bits (10GE/25GE/50GE/100GE/200GE

192 bits (400GE)

TX egress timestamp bus when Ethernet rate is 10GE/ 25GE/50GE/100GE/200GE/400GE.
The bus presents an egress timestamp for the TX packet transmitted with the fingerprint given by o_ptp_ets_fp signal.
  • o_ptp_ets[95:0] is valid only when o_ptp_ets_valid[0]=1.
  • o_ptp_ets[191:96] is valid only when o_ptp_ets_valid[1]=1.

The egress timestamp applies for 2-step and 1-step PTP packets.

o_ptp_ets_fp[w]

o_ptp_ets_fp[w*2],

where w is 8-12

w bits (10GE/25GE/50GE/100GE/200GE)

(w*2) bits (400GE)

TX egress timestamp fingerprint when Ethernet rate is 10GE/25GE/ 50GE/100GE/200GE/400GE.
The bus presents the fingerprint for the current 2-step egress timestamp. You use the fingerprint to determine which TX packet the timestamp belongs to.
  • o_ptp_ets_fp[w-1:0] is valid only when o_ptp_ets_valid[0] = 1.
  • o_ptp_ets_fp[w*2-1:w] is valid only when o_ptp_ets_valid[1] = 1.

The egress timestamp applies for 2-step and 1-step PTP packets.