AM79C978 Advanced Micro Devices, AM79C978 Datasheet - Page 77

• Manufacturer Part Number: AM79C978
• Description: Single-Chip 1/10 Mbps PCI Home Networking Controller
• Manufacturer: Advanced Micro Devices

AID Symbols 1 through 6
AID symbols 1 through 4 are used to identify individual
stations to enable reliable collision detection as de-
scribed in the Collisions section. Symbols 5 and 6 are
used to transmit remote control management com-
mands across the network. Coding and timing details
are as follows.
The SYNC interval is followed by six AID symbols
(symbols 1 through 6). Transmit timing is shown in Fig-
ure 38; receive timing in Figure 39. Data is encoded in
AID slice threshold
pulse 0
SYNC_START
TIC=0
pulse 0
AID Symbol 0
SYNC_START
TIC=0
Detected envelope
AID Symbol 0
SYNC_END
END_RCV_BLANK
TIC=126
Figure 38. AID Symbol Transmit Timing
Figure 39. AID Symbol Receive Timing
pulse 1
SYNC_END
TIC=129
TIC=0
and
TIC=126
pulse 1
AID_Position_0
TIC=128
and
TIC=0
Transmitter
AID Symbol 1
AID_Position_1
Receiver
Am79C978
TIC=66
AID_Position_2
AID_Position_0
TIC=86
pulse 2
shown in position 1
AID Symbol 1
AID_Position_3
TIC=106
AID_Position_1
TIC=66
the relative position of each pulse with respect to the
previous one. A pulse may occur at one, and only one,
of the four possible positions within an AID symbol
yielding two bits of data coded per AID symbol.
The decoded bits from the AID symbols 1 to 4 produce
eight bits of Access ID which is used to identify individ-
ual HomePNA stations and to detect collisions. The
MSB is encoded in AID Symbol 1 and is the leftmost bit
in Table 12.
TIC=126
AID_Position_2
TIC=86
pulse 2
shown in position 1
TIC=106
AID_Position_3
TIC=129
TIC=0
and
TIC=126
TIC=12
8 and
TIC=0
AID Symbol 2
AID Symbol 2
AID_GUARD_INTERVAL
22206B-42
22206B-43
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