AM79C864AKCW AMD [Advanced Micro Devices], AM79C864AKCW Datasheet - Page 37

• Manufacturer Part Number: AM79C864AKCW
• Description: Physical Layer Controller With Scrambler (PLC-S)
• Manufacturer: AMD [Advanced Micro Devices]

Decoder
The Decoder performs the 4B/5B decoding of received
data symbols. The five bits of data from the Elasticity
Buffer are decoded into four bits of data and one control
bit, with the high order bit being the control bit. The de-
coded symbol pairs are then sent to the MAC. Although
the Decoder operates on symbol pairs, each symbol is
decoded independently of the other.
Until the PCM has completed establishing a connection
for the physical link, the PHY_INVALID symbol is output
by the Decoder. Whether the output of the decoder or
Notes:
1. Class = S or PCM_MAINT
2. Not (SC_ JOIN and not START_SCRUBBING)
3. SET_SC_ JOIN
4. TPC > T_SCRUB and (SC_JOIN and not
5. SET_SC_ JOIN
6. Not SET_SC_JOIN and START_SCRUBBING
7. TPC > T_SCRUB
START_SCRUBBING)
Inserted
PCI3
Reset
1
Figure 3. PCI State Machine
6
P R E L I M I N A R Y
Am79C864A
Removed
Remove
7
Scrub
PCI0
PCI2
Signals on PCI State Machine:
SC_JOIN:
This signal is output by the PCM state machine and indi-
cates that is has reached the ACTIVE state and scrubbing
may be started.
SET_SC_JOIN:
This signal is output by the PCM state machine and is as-
serted during the clock cycle before SC_JOIN is asserted.
CLASS_S:
This bit in the PLC_CNTRL_B register, when set, indicates
that the station is of type CLASS_S.
START_SCRUBBING:
This signal is asserted by the PCM state machine when the
station has joined the ring (SC_JOIN is asserted) and a
Break condition occurs. It causes the PCI state machine to
enter the REMOVE_SCRUB state.
PCM_MAINT:
This signal indicates that the PCM state machine is in the
MAINT state.
the data on TX 9–0 is output on RX 9–0 is dependent on
the CLASS_S bit in the PLC_CNTRL_B register. In ad-
dition, a Violation symbol (V) shall be generated when
an input error condition has been detected, such as an
Elasticity Buffer error (buffer overflow or underflow).
PHY_INVALID takes precedence over Violation, so if an
Elasticity Buffer error occurs while the Current Line
State
PHY_INVALID (1F in hex) is given to MAC.
The symbol decoding is shown in Table 15.
4
5
3
is
Quiet,
2
15535B-15
Insert
Scrub
PCI1
Halt,
Master,
or
Noise
AMD
3-39
then