VSC7212 Datasheet, PDF (15/34 Pages) Vitesse Semiconductor Corporation – Gigabit Interconnect Chip

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Preliminary Data Sheet
VSC7212
Gigabit Interconnect Chip
Figure 10: State Diagram of the Invalid Transmission Counter
(Unconditional)
Valid
Invalid
Invalid
Invalid
Invalid
0
1
2
3
4
Mis-Aligned
“Comma”
Valid
Valid
Valid
Link Status Outputs
On the receiver output bus, the ERR, KCH and IDLE outputs indicate status for the receiver as shown
below in Table 7. Since this status is encoded, multiple conditions could occur simultaneously so the states are
prioritized as indicated (1 being highest priority). For example, if both Out-of-Band and Disparity Errors occur,
only an Out-of-Band Error is reported because it has higher priority.
The ERR, KCH and IDLE status signals apply to the data on R(7:0) on a per-character basis. The only
exception to this is the Underrun/Overrun indication, which is asserted coincident with the duplicated character
when an underrun occurs, and is asserted following the deleted character (i.e. on the cycle where the deleted
character should have appeared) when an overrun occurs.
Table 7: Receiver Status Signals
ERR
0
0
0
0
1
1
1
1
KCH
0
0
1
1
0
0
1
1
IDLE
0
1
0
1
0
1
0
1
Priority
7
1
6
5
3
4
2
2
Link Status
Valid Data Transmission: A valid 10B data character with correct
disparity was received. The correctly decoded version of this character is
on R(7:0).
Underrun/Overrun Error: The elastic buffer has not been able to add/
drop an IDLE when required. Data on R(7:0) is invalid.
Kxx.x Special Character Detected (not IDLE): A valid 10B special
character with correct disparity was received. The correctly decoded
version of this character, per Table 3, is on R(7:0).
IDLE Detected: A valid IDLE character (K28.5) with correct disparity
was received. The correctly decoded version of this character, per Table 3,
is on R(7:0).
Out-of-band Error Detected: A character was received which was not a
valid 10B data or control character. Data on R(7:0) is invalid.
Disparity Error Detected: A valid 10B character was received which did
not have the expected disparity. R(7:0) is invalid.
Loss of Synchronization: The receiver state machine is in the Loss-of-
Sync state. Data on R(7:0) is invalid.
RESYNC: The receiver state machine is in the re-Synchronization state.
Data on R(7:0) is a decoded version of K28.1, K28.5 or K28.7.
G52268-0, Rev 3.3
04/10/01
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