Motorola MC92603 Reference Manual page 56

Ethernet Compliant Applications Modes (COMPAT = High)
Initially, the receiver must attain byte alignment through the detection of four COMMA
code groups with the same alignment as explained in Section 3.5.1, "Non-Aligned Mode
(BSYNC = Low)." Next, the receiver must attain stream alignment as described and shown
in Figure 36-9 of the IEEE Std. 802.3-2002 specification [4].
The RECV ERR output remains high until both alignments are attained.
_x_
The receiver then searches for a Start_of_Packet code group (/S/). On detection of a
Start_of_Packet, the receiver replaces that code group with a preamble code group (0x55)
and present this data on the receiver data output REC
RECV x DV output is raised. This is per Figures 36-7a and 36-7b of IEEE Std. 802.3-2002
_ _
specification [4].
Data continues to be presented on the data outputs, and the RECV
high until an End_of_Packet code group (/T/) is received. At this point the RECV
output is negated low and remains low until the next Start_of_Packet is received.
When operating in GMII mode, the receiver status is reported by RECV_x_ERR and
RECV_x_DV and encoded on the RECV_x_[7:0] data signals, as shown in Table 3-10
RECV_x_ RECV_x_
ERR DV
High Low
Low Low
Low High
High High
High High
High High
High High
High High
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MC92603 Quad Gigabit Ethernet Transceiver Reference Manual
Table 3-10. Receiver Status in GMII Mode
RECV_x_ RECV_x_
RCLK_B [7:0]
Low 0x00
Low Don't care
Low Data
Low 0x20
Low 0x10
Low 0x08
Low 0x04
Low 0x02
7 through RECV
_x_
Description
Not byte sync: The receiver is in start-up or has lost byte
alignment and is searching for alignment.
Normal inter-frame gap
Normal operation, valid data code group received.
Error propagation
Disparity error
Code error
Overrun
Underrun
x_0 as the
_
x DV output remains
_ _
x DV
_ _
.
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