NFC Message in Default Mode - 12.0 English

PG074 Aurora 64B/66B LogiCORE IP Product Guide

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12.0 English

To send an NFC message to a channel partner, the user application asserts s_axi_nfc_tx_tvalid and writes an 8-bit pause count to s_axi_nfc_tx_tdata[8:15] . The pause code indicates the minimum number of cycles the channel partner must wait after receiving an NFC message prior to resuming data send. The number of user_clk cycles without data is equal to s_axi_nfc_tx_tdata + 1.

When asserted, the s_axi_nfc_tx_tdata[7] signal indicates nfc_xoff , requesting that the channel partner stop sending data until it receives a non-XOFF NFC message or reset. When a request is transmitted with PAUSE and XOFF both set to 0, NFC is set to XON mode. To cancel XOFF mode, all 0s (XON) should be transmitted. After reception of this XON request, any new NFC request is honored by the core. The user application must hold s_axi_nfc_tx_tvalid , s_axi_nfc_tx_tdata[8:15] , and s_axi_nfc_tx_tdata[7] ( nfc_xoff , if used) until s_axi_nfc_tx_tready is asserted on a positive user_clk edge indicating that the core can transmit the NFC message.

Aurora 64B/66B cores cannot transmit data while sending NFC messages. s_axi_tx_tready is always deasserted on the cycle following an s_axi_nfc_tx_tready assertion. NFC Completion mode is available only for the framing Aurora 64B/66B interface.