Texas Instruments SM320C6455-EP manual Emac Device-Specific Information, Interface Modes

Models: SM320C6455-EP

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SM320C6455-EP

FIXED-POINT DIGITAL SIGNAL PROCESSOR

www.ti.com

SPRS462B – SEPTEMBER 2007 – REVISED JANUARY 2008

7.14.1 EMAC Device-Specific Information

Interface Modes

The EMAC module on the C6455 supports four interface modes: Media Independent Interface (MII), Reduced Media Independent Interface (RMII), Gigabit Media Independent Interface (GMII), and Reduced Gigabit Media Independent Interface (RGMII). The MII and GMII interface modes are defined in the IEEE 802.3-2002 standard.

The RGMII mode of the EMAC conforms to the Reduced Gigabit Media Independent Interface (RGMII) Specification (version 2.0). The RGMII mode implements the same functionality as the GMII mode, but with a reduced number of pins. Data and control information is transmitted and received using both edges of the transmit and receive clocks (TXC and RXC).

Note: The EMAC internally delays the transmit clock (TXC) with respect to the transmit data and control pins. Therefore, the EMAC conforms to the RGMII-ID operation of the RGMII specification. However, the EMAC does not delay the receive clock (RXC); this signal must be delayed with respect to the receive data and control pins outside of the DSP.

The RMII mode of the EMAC conforms to the RMII Specification (revision 1.2), as written by the RMII Consortium. As the name implies, the Reduced Media Independent Interface (RMII) mode is a reduced pin count version of the MII mode.

Interface Mode Select

The EMAC uses the same pins for the MII, GMII, and RMII modes. Standalone pins are included for the RGMII mode due to specific voltage requirements. Only one mode can be used at a time. The mode used is selected at device reset based on the MACSEL[1:0] configuration pins (for more detailed information, see Section 3, Device Configuration). Table 7-70shows which multiplexed pins are used in the MII, GMII, and RMII modes on the EMAC. For a detailed description of these pin functions, see Table 2-3, Terminal Functions.

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Texas Instruments SM320C6455-EP manual Emac Device-Specific Information, Interface Modes