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Backplane Application Modes (COMPAT = Low)
2.3.2
Repeater Mode Operation
Although repeater mode is primarily used for factory engineering, it may be used by the
application as described in Section 5.5, "Repeater Mode." The repeater enable signal,
REPE, should be configured low during a normal transceiver operation.
2.4
Backplane Application Modes (COMPAT = Low)
When the configuration control signal, COMPAT, is low, the MC92603 is in the 'backplane
application mode.' In this application mode, the MC92603 transmitters accept either
uncoded data, where the input data is encoded internally by an 8B/10B encoder, or coded
data, where the input data is pre-encoded and the internal encoder is bypassed.
The interface for the backplane application mode is either 8 or 10 bits wide, or optionally
4 or 5 bits, as shown in Table 2-2.
2.4.1
Transmitting Uncoded Data—8-/4-Bit Modes
The settings for the transmitter control signals when sending uncoded 8-bit or reduced
interface 4-bit data is shown in Table 2-3.
When XMIT_x_ENABLE is low, an IDLE (K28.5) code group of proper running disparity
is generated. The states of the XMIT_x_7–XMIT_x_0, XMIT_x_K, and XMIT_x_ERR
signals are ignored. This allows the link partner's receiver to maintain alignment when
transmission of data is not needed.
Table 2-3. Transmitter Control States for Uncoded Data (TBIE = Low)
XMIT_x_ENABLE
XMIT_x_ERR
Low
Don't care
High
High
High
High
When XMIT_x_ENABLE is high, uncoded data is presented in 8-/4-bit bytes to the input
register through the XMIT_x_7–XMIT_x_0 signals. The uncoded data is coded into 10-bit
transmission code groups using an on-chip 8B/10B encoder. 8B/10B coding ensures DC
balance across the link and sufficient transition density to facilitate reliable data and clock
recovery. The XMIT_x_7–XMIT_x_0 signals are interpreted as normal data when the
XMIT_x_K signal is low.
2-6
MC92603 Quad Gigabit Ethernet Transceiver Reference Manual
XMIT_x_K
Don't care
Transmit IDLE (K28.5), ignore XMIT_x_7–XMIT_x_0 data inputs
Low
Low
Transmit data present on XMIT_x_7–XMIT_x_0 data inputs
Low
High
Transmit control data present on XMIT_x_7–XMIT_x_0 data
inputs
Low
High
Transmit disparity-style word synchronization event if
XMIT_x_7–0 data inputs = 0xAD. The transmitter inputs will be
ignored while sending these 16 code groups.
High
Don't care
Create an invalid 10-bit code group to be transmitted
Description
MOTOROLA
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