Texas Instruments TMS320C645x DSP Emac and Mdio Signals for MII Interface, Mtxen, Mrxdv, Control

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EMAC Functional Architecture

Table 2 summarizes the individual EMAC and MDIO signals for the MII interface. For more information, refer to either the IEEE 802.3 standard or ISO/IEC 8802-3:2000(E).

The EMAC module does not include a transmit error (MTXER) pin. If a transmit error occurs, CRC inversion is used to negate the validity of the transmitted frame.

		Table 2. EMAC and MDIO Signals for MII Interface
Signal Name	I/O	Description
MTCLK	I	Transmit clock (MTCLK). The transmit clock is a continuous clock that provides the timing
		reference for transmit operations. The MTXD and MTXEN signals are tied to this clock. The
		clock is generated by the PHY and is 2.5 MHz at 10 Mbps operation and 25 MHz at 100
		Mbps operation.
MTXD[3:0]	O	Transmit data (MTXD). The transmit data pins are a collection of 4 data signals comprising 4
		bits of data. MTDX0 is the least-significant bit (LSB). The signals are synchronized by MTCLK
		and valid only when MTXEN is asserted.
MTXEN	O	Transmit enable (MTXEN). The transmit enable signal indicates that the MTXD pins are
		generating nibble data for use by the PHY. It is driven synchronously to MTCLK.
MCOL	I	Collision detected (MCOL). The MCOL pin is asserted by the PHY when it detects a collision
		on the network. It remains asserted while the collision condition persists. This signal is not
		necessarily synchronous to MTCLK nor MRCLK. This pin is used in half-duplex operation
		only.
MCRS	I	Carrier sense (MCRS). The MCRS pin is asserted by the PHY when the network is not idle in
		either transmit or receive. The pin is de-asserted when both transmit and receive are idle.
		This signal is not necessarily synchronous to MTCLK or MRCLK. This pin is used in
		half-duplex operation only.
MRCLK	I	Receive clock (MRCLK). The receive clock is a continuous clock that provides the timing
		reference for receive operations. The MRXD, MRXDV, and MRXER signals are tied to this
		clock. The clock is generated by the PHY and is 2.5 MHz at 10 Mbps operation and 25 MHz
		at 100 Mbps operation.
MRXD[3:0]	I	Receive data (MRXD). The receive data pins are a collection of 4 data signals comprising 4
		bits of data. MRDX0 is the least-significant bit (LSB). The signals are synchronized by
		MRCLK and valid only when MRXDV is asserted.
MRXDV	I	Receive data valid (MRXDV). The receive data valid signal indicates that the MRXD pins are
		generating nibble data for use by the EMAC. It is driven synchronously to MRCLK.
MRXER	I	Receive error (MRXER). The receive error signal is asserted for one or more MRCLK periods
		to indicate that an error was detected in the received frame. This is meaningful only during
		data reception when MRXDV is active.
MDCLK	O	Management data clock (MDCLK). The MDIO data clock is sourced by the MDIO module on
		the system. It is used to synchronize MDIO data access operations done on the MDIO pin.
		The frequency of this clock is controlled by the CLKDIV bits in the MDIO control register
		(CONTROL).
MDIO	I/O	Management data input output (MDIO). The MDIO pin drives PHY management data into and
		out of the PHY by way of an access frame consisting of start of frame, read/write indication,
		PHY address, register address, and data bit cycles. The MDIO pin acts as an output for
		everything except the data bit cycles, when the pin acts as an input for read operations.

SPRU975B –August 2006	Ethernet Media Access Controller (EMAC)/Management Data Input/Output (MDIO)	17
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