QT2022/32 - Data Sheet: DS3051
8.2.13 Backwards Compatibility Control Pin (LEGACY)
The LEGACY pin is used to revert several key register map definitions to be compatible with the AMCC QT2021
SerDes. When the LEGACY pin is low, the new QT2022/32 register map definitions are used. When high, the
QT2021 definitions are used.
Table 8 lists the register map definition differences affected by the LEGACY pin. Table lists all changes to chip
function affected by the LEGACY pin. The state of the LEGACY pin is shown in MDIO register bit 1.D002h.15.
Table 19: LEGACY Pin Register Map Definition Changes
Register Definition
LEGACY = 0
Register Definition
LEGACY = 1
Item
Register
1
2
3
4
5
1.9001h.6
TXFAULT Enable
0 = disabled (default)
1 = enabled
TXFAULT Enable
0 = disabled
1 = enabled (default)
1.9001h.7
1.9001h.8
1.9001h.9
1.9003h.4
Laser Output Power Fault Enable
0 = disabled
1 = enabled (default)
Reserved, RO
Reserved, RO
Reserved, RO
Laser Temp Fault Enable
0 = disabled
1 = enabled (default)
Laser Bias Current Fault Enable
0 = disabled
1 = enabled (default)
PMA Receive Local Fault, RO/LH
Defined as: NOT(Receive PLL Lock)
PMA Receive Local Fault, RO/LH
Defined as: NOT(Receive PLL Lock) or
RXLOSB_I==0
6
7
8
1.9003h.5
1.9004h.0
1.9004h.3
Receive Optical Power Fault, RO
linked to DOM alarm 1.A071h.7:6
Reserved, RO
PHY_XS Transmit Local Fault, RO/LH
Defined as: NOT(TxXAUI Lane Align)
PHY_XS Transmit Local Fault, RO/LH
Defined as: NOT(TxXAUI CDR lock<3:0>)
PCS Transmit Local Fault, RO/LH
Defined as: Transmit FIFO overflow/underflow
error
PCS Transmit Local Fault, RO/LH
Defined as: NOT(TxXAUI Lane Sync) or NOT
(TxXAUI Lane Align)
9
1.9004h.4
PMA Transmit Local Fault, RO/LH
Defined as: Transmit PLL not locked
PMA Transmit Local Fault, RO/LH
Defined as: (Transmit PLL not locked) OR
(TXFAULT)
10
11
12
1.9004h.7
1.9004h.8
1.9004h.9
Laser Output Power Fault, RO
linked to DOM alarm 1.A070h.1:0
Reserved, RO
Reserved, RO
Reserved, RO
Laser Temp Fault Enable, RO
linked to DOM alarm 1.A070h.7:6
Laser Bias Current Fault, RO
linked to DOM alarm 1.A070h.3:2
58
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