AM79C978A AMD [Advanced Micro Devices], AM79C978A Datasheet - Page 76

• Manufacturer Part Number: AM79C978A
• Description: Single-Chip 1/10 Mbps PCI Home Networking Controller
• Manufacturer: AMD [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 described
in the Collisions section. Symbols 5 and 6 are used to
transmit remote control management commands across
the network. Coding and timing details are as follows.
The SYNC interval is followed by six AID symbols (sym-
bols 1 through 6). Transmit timing is shown in Figure 39;
receive timing in Figure 40. Data is encoded in the relative
position of each pulse with respect to the previous one. A
76
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 39. AID Symbol Transmit Timing
Figure 40. AID Symbol Receive Timing
pulse 1
SYNC_END
TIC=129
and
TIC=0
TIC=126
pulse 1
AID_Position_0
TIC=129
and
TIC=0
Transmitter
AID Symbol 1
Am79C978A
AID_Position_1
Receiver
TIC=66
AID_Position_2
AID_Position_0
TIC=86
pulse 2
shown in position 1
AID Symbol 1
TIC=106
AID_Position_3
AID_Position_1
TIC=66
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 individual
HomePNA stations and to detect collisions. The MSB is
encoded in AID Symbol 1 and is the leftmost bit in
Table 14.
TIC=126
AID_Position_2
TIC=86
pulse 2
shown in position 1
TIC=106
AID_Position_3
TIC=128
and
TIC=0
TIC=126
TIC=129
and
TIC=0
AID Symbol 2
AID Symbol 2
AID_GUARD_INTERVAL
22399A-42
22399A-43