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MC92603 Quad Gigabit Ethernet Transceiver Reference Manual
MOTOROLA
Backplane Application Modes (COMPAT = Low)
2.4.2
Transmitting Coded Data—10-/5-Bit Modes
This operating mode is specified when the TBIE input is high. The state of COMPAT input
does not affect the transmitter’s operation.
In this mode, 10-bit coded data may be transmitted, bypassing the internal 8B/10B encoder.
The 10 bits of data to transmit are presented on the XMIT_x_7–XMIT_x_0 inputs along
with bits 9 and 8 on the XMIT_x_ERR and XMIT_x_ENABLE inputs, respectively. The
10-bit coded data is transmitted as shown in Table 2-5.
The XMIT_x_K signal is ignored by the transmitter in the backplane 10-/5-bit modes, but,
it is used by the receiver.
When using the MC92603 in the backplane applications (COMPAT = low), it is not
necessary to use the 8B/10B code set. However, special care must be taken. The data must
exhibit the same properties as 8B/10B coded data. DC balance must be maintained and
there must be sufficient transition density to ensure reliable clock and data recovery at the
receiver. If running in the Ethernet TBI or RTBI mode, the data will be 8B/10B data.
NOTE
If the code used is not 8B/10B, then it must support the K28.5
IDLE code (this only applies to backplane mode; Ethernet-TBI
mode is assumed to use 8B/10B). The code must be such to
guarantee that no two codes, when concatenated, produce the
8-bit COMMA pattern as defined above.
The receivers require that COMMA code groups (K28.1, K28.5, or K28.7) be transmitted
for byte synchronization. The 8-bit pattern (‘00111110xx’ or ‘11000001xx,’ ordered from
bits 0–7) is used for alignment and link-to-link synchronization when operating in any of
the byte or word synchronization modes. The pattern of code groups and data required to
achieve word synchronization (available only in backplane application mode,
COMPAT = low) depends on the configuration of the receiver. The appropriate sequence
must be applied through the 10-/5-bit interface.
Table 2-5. Transmitter Input States for Coded Data (TBIE = High)
XMIT_x_K
XMIT_x_ERR
XMIT_x_ENABLE
XMIT_x_7–
XMIT_x_0
Description
Used by receiver
Data bit 9
Data bit 8
Data bits 7–0
Data bits 9–0
Summary of Contents for MC92603
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