Flow Control Interface (IEEE 802.3) - 9.0 English

Tri-Mode Ethernet MAC LogiCORE IP Product Guide (PG051)

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See Flow Control Interface Signal Pinout describes the signals used to request a flow-control action from the transmit engine. Valid flow control frames received by the MAC are automatically handled (if the MAC is configured to do so). The pause value in the received frame is used to inhibit the transmitter operation for the time defined in IEEE 802.3-2008 specification. The frame is then passed to the client with rx_axis_mac_tuser asserted to indicate to the client that it should be dropped. See Flow Control Using IEEE 802.3.

Table 1. Flow Control Interface Signal Pinout
Signal Direction Clock Domain Description
pause_req In tx_mac_aclk Pause request: Upon request the MAC transmits a pause frame after the completion of the current data packet. See Transmitting a Pause Control Frame.
pause_val[15:0] In tx_mac_aclk Pause value: Inserted into the parameter field of the transmitted pause frame.
  1. All signals are active-High.
  2. Continuous pause requests are not recommended to provide to the MAC. Assert a pause request pulse and wait for the respective pause valid assertion before applying another pause request pulse.