EMAC
Physical
Layer
Device
(PHY)
MDIO
RMII_TXD[1:0]
50 MHz
Transformer
RJ-45
RMII_TXEN
RMII_RMREFCLK
RMII_RXD[1–0]
RMII_CRS_DV
RMII_RXER
MDIO_CLK
MDIO_DATA
Integration
Table 14-6. GMII Interface Signal Descriptions in MII (100/10Mbps) Mode (continued)
Signal
Type
Description
The receive data valid signal indicates that the MRXD pins are generating nibble
MRXDV
I
data for use by the 3PSW. It is driven synchronously to MRCLK.
Management data clock (MDIO_CLK). The MDIO data clock is sourced by the
MDCLK
O
MDIO module on the system. It is used to synchronize MDIO data access
operations done on the MDIO pin.
MDIO DATA(MDI0_D). MDIO data pin drives PHY management data into and
out of the PHY by way of an access frame consisting of start of frame, read/write
MDIO
I/O
indication,PHY address, register address, and data bit cycles. The MDIO_D pin
acts as an output for all but the data bit cycles at which time it is an input for read
operations.
14.2.6 RMII Signal Connections and Descriptions
shows a device with integrated 3PSW and MDIO interfaced via a RMII connection in a typical
system.
The individual CPSW and MDIO signals for the RMII interface are summarized in
.
For more information, see either the IEEE 802.3 standard or ISO/IEC 8802-3:2000(E).
Figure 14-4. RMII Interface Connections
Table 14-7. RMII Interface Signal Descriptions
Signal
Type
Description
Transmit data. The transmit data pins are a collection of 2 bits of data.
RMII_TXD[1-0]
O
RMII_TXD0 is the least-significant bit (LSB). The signals are synchronized by
RMII_REFCLK and valid only when RMII_TXEN is asserted.
Transmit enable. The transmit enable signal indicates that the RMII_TXD pins
RMII_TXEN
O
are generating data for use by the PHY. RMII_TXEN is synchronous to
RMII_MHZ_50_CLK.
RMII reference clock.
RMII_REFCLK
I
The reference clock is used to synchronize all RMII signals. RMII_REFCLK must
be continuous and fixed at 50 MHz.
Receive data. The receive data pins are a collection of 2 bits of data.
RMII_RXD0 is the least-significant bit (LSB). The signals are synchronized by
RMII_RXD[1-0]
I
RMII_REFCLK and valid only when RM_CRS_DV is asserted and RMII_RXER is
deasserted.
Carrier sense/receive data valid. Multiplexed signal between carrier sense and
RMII_CRS_DV
I
receive data valid.
1173
SPRUH73H – October 2011 – Revised April 2013
Ethernet Subsystem
Copyright © 2011–2013, Texas Instruments Incorporated