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Transmitter Redundant Link Operation
If XMIT_x_ERR transitions to high as XMIT_x_ENABLE transitions to low, this is
defined as a 'carrier extension.' The 'carrier extension' state is a half-duplex feature and is
not supported in the MC92603.
XMIT_x_ERR will be ignored while XMIT_x_ENABLE is low.
Transmitting in the Ethernet-compatability mode with the reduced (RGMII) interface is
shown in Table 2-8. The transmitter functional operation is the same as discussed above,
except the data is entered on both edges of the transmitter input clock, XMIT_x_CLK.
Table 2-8. Transmitter Inputs for RGMII Operating Mode
Data on Rising Edge of XMIT_x_CLK
GMII_TX_EN
Data bits 3–0
The 8 bits of uncoded data are entered with the least significant 4 bits on the rising clock
and the most significant bits on the falling clock edge.
2.5.2
Transmitting Coded Data—TBI or RTBI Modes
The PMA sublayer of the 1000BASE-X specification does not require any functional
differences in the transmitter from that used in the backplane application mode. Therefore,
when operating in a mode specified when the TBIE input is high, the state of the COMPAT
input does not affect the transmitter's operation. See Section 2.4.2, "Transmitting Coded
Data—10-/5-Bit Modes."
2.6
Transmitter Redundant Link Operation
The MC92603 is configured as a dual channel SerDes, with redundant link input and
outputs, if the enable redundancy signal, ENAB_RED, is asserted high. Only the data
interface to channels A and B will accept data to be transmitted. This data will be
transmitted over the appropriate link as specified by the BROADCAST and
XCVR_x_RSEL inputs as shown in Table 2-9 and Table 2-10.
When operating in the redundancy mode, the transmitter
channels C and D input signals (XMIT_C_--- and
XMIT_D_---), should be terminated low.
XCVR_A_RSEL, and XCVR_B_RSEL selects the primary or secondary link I/Os for
channels A and B, respectively. The BROADCAST control signal enables both channel A
and B link outputs to transmit data at their data interface, while enabling the receiver links
to receive serial data defined by the XCVR_x_RSEL control signal. See Section 3.3.6,
"Receiver Redundant Link Operation," for more on receiver redundancy.
2-12
MC92603 Quad Gigabit Ethernet Transceiver Reference Manual
Data on Falling Edge of XMIT_x_CLK
GMII_TX_EN (XOR) GMII_TX_ER
Data bits 7–4
NOTE
MC92603 Signal Name
XMIT_x_ENABLE
XMIT_x_3/XMIT_x_0
MOTOROLA
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