
RGMII Transmit
On transmit, all data transfers are synchronous to both edges of tx_clk. The RGMII control signal tx_control
is asserted to indicate the start of a new frame and remains asserted until the last upper nibble of the frame
is present on the rgmii_out[3:0] bus. Between frames, tx_control remains deasserted.
Figure 7-16: RGMII Transmit in 10/100 Mbps
tx_clk
tx_control
rgmii_out[3:0] 00 5 D 0 5 1 6 1 9 1
Figure 7-17: RGMII Transmit in Gigabit Mode
tx_clk
tx_control
rgmii_out[3:0] 00 5 D 0 5 4 5 E 5 F 5 0 6 0
If a frame is received on the Avalon-ST interface with an error (ff_tx_err asserted with ff_tx_eop), the
frame is subsequently transmitted with the RGMII tx_control error signal (at the falling edge of tx_clk)
at any time during the frame transfer.
Figure 7-18: RGMII Transmit with Error in 1000 Mbps
tx_clk
tx_control
rgmii_out[3:0] 00 5 0 4 6 0 1 0 0 8 0 9 0
RGMII Receive
On receive all signals are sampled on both edges of rx_clk. The RGMII control signal rx_control is asserted
by the PHY to indicate the start of a new frame and remains asserted until the last upper nibble of the frame
is present on rgmii_in[3:0] bus. Between frames, rx_control remains deasserted.
Figure 7-19: RGMII Receive in 10/100 Mbps
rx_clk
rx_control
rgmii_in[3:0] 00 5 D 0 5 1 6 1 9 0
Interface Signals
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UG-01008
RGMII Transmit
7-42
2014.06.30
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