Maxim Integrated DS33Z41 - Manual (Page 47)

DS33Z41 Quad IMUX Ethernet Mapper
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8.14.1 MII Mode
The Ethernet interface can be configured for MII operation by setting the hardware pin RMIIMIIS low. The MII
interface consists of 17 pins. For instructions on clocking the Ethernet Interface while in MII mode, see Section
8.2.2 . Diagrams of system connections for MII operation are shown in Figure 8-8 and Figure 8-9 .
8.14.2 RMII Mode
The Ethernet interface can be configured for RMII operation by setting the hardware pin RMIIMIIS high. RMII
interface operates synchronously from the external 50MHz reference (REF_CLK). Only 7 signals are required.
The following figure shows the RMII architecture. Note that DCE mode is not supported for RMII mode and RMII
is valid only for full duplex operation.
Figure 8-10. RMII Interface
TXD[1:0]
TX_EN
REF_CLK
RXD[1:0]
CRS_DV
MAC MII to RMII PHY RMII to MII
TX_EN
TXD[3:0]
TX_ERR
TX_CLK
RX_CRS
RX_DV
RX_CRS
RX_CLK
TX_EN
TXD[3:0]
TX_ERR
TX_CLK
CRS
RX_DV
RXD[3:0]
RX_ER
RX_CLK