40.4 Signal Interfaces

The GMAC includes the following signal interfaces:

  • Media interface supports MII/RMII and connects to the external PHY
  • Management Data Input/Output (MDIO) connects to the external PHY for management
  • Configuration interface
  • System bus interface for direct memory access (DMA)
  • GTSUCOMP signal for TSU timer count value comparison
Table 40-1. GMAC Connections to PHY in Different Modes
Signal Name Function MII RMII
GTXCK(1) Transmit Clock or Reference Clock TXCK REFCK
GTXEN Transmit Enable TXEN TXEN
GTX[3..0] Transmit Data TXD[3:0] TXD[1:0]
GTXER Transmit Coding Error TXER Not Used
GRXCK Receive Clock RXCK Not Used
GRXDV Receive Data Valid RXDV CRSDV
GRX[3..0] Receive Data RXD[3:0] RXD[1:0]
GRXER Receive Error RXER RXER
GCRS Carrier Sense and Data Valid CRS Not Used
GCOL Collision Detect COL Not Used
GMDC Management Data Clock MDC MDC
GMDIO Management Data Input/Output MDIO MDIO
Note:
  1. Input only. GTXCK must be provided with a 25 MHz/50 MHz external crystal oscillator for MII / RMII interfaces, respectively.