
TNETX4090
ThunderSWITCH II 9-PORT  100-/1000-MBIT/S  ETHERNET SWITCH
SPWS044E ± DECEMBER 1997 ± REVISED AUGUST 1999
GMII (port 8)
Figures 18±20 show the timing for the 100-/1000-Mbit/s  GMII when operating at 1000 Mbit/s.
Both Mxx_CRS and Mxx_COL are driven asynchronously by the PHY. Mxx_RXD7±MxxRXD0 is driven by the PHY on the falling edge of Mxx_RCLK. Mxx_RXD7±MxxRXD0 timing must be met during clock periods in which Mxx_RXDV is asserted. Mxx_RXDV is asserted and deasserted by the PHY on the falling edge of Mxx_RCLK. Mxx_RXER is driven by the PHY on the falling edge of Mxx_RCLK.
GMII receive (see Figure 18)
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1  | tsu(Mxx_RXD)  | Setup time, Mxx_RXD7±Mxx_RXD0 valid before Mxx_RCLK↑  | 2  | ns  | 
1  | tsu(Mxx_RXDV)  | Setup time, Mxx_RXDV valid before Mxx_RCLK↑  | 2  | ns  | 
1  | tsu(Mxx_RXER)  | Setup time, Mxx_RXER valid before Mxx_RCLK↑  | 2  | ns  | 
2  | th(Mxx_RXD)  | Hold time, Mxx_RXD7±Mxx_RXD0 valid after Mxx_RCLK↑  | 1  | ns  | 
2  | th(Mxx_RXDV)  | Hold time, Mxx_RXDV valid after Mxx_RCLK↑  | 1  | ns  | 
2  | th(Mxx_RXER)  | Hold time, Mxx_RXER valid after Mxx_RCLK↑  | 1  | ns  | 
Mxx_RCLK
1 
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Mxx_RXD7±Mxx_RXD0
Mxx_RXDV
Mxx_RXER
Figure 18. GMII Receive
Mxx_CRS and Mxx_COL are driven asynchronously by the PHY. Mxx_GTCLK is derived directly from Mxx_RFCLK. Mxx_TXD7±Mxx_TXD7 is driven by the reconciliation sublayer synchronous to the Mxx_GTCLK. Mxx_TXEN is asserted and deasserted by the reconciliation sublayer synchronous to the Mxx_GTCLK rising edge. Mxx_TXER is driven synchronous to the rising edge of Mxx_GTCLK.
GMII transmit (see Figure 19)
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1  | td(Mxx_TXD)  | Delay time, from Mxx_GTCLK↑ to Mxx_TXD3±MxxTXD0 valid  | 1.5  | 4.5  | ns  | ||||||||||
1  | td(Mxx_TXEN)  | Delay time, from Mxx_GTCLK↑ to Mxx_TXEN valid  | 1.5  | 4.5  | ns  | ||||||||||
1  | td(Mxx_TXER)  | Delay time, from Mxx_GTCLK↑ to Mxx_TXER valid  | 1.5  | 4.5  | ns  | ||||||||||
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Mxx_TXD7±Mxx_TXD0  | 
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  | Mxx_TXER  | 
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Figure 19. GMII Transmit
64  | POST OFFICE BOX 655303 •DALLAS, TEXAS 75265  |