參數(shù)資料
型號(hào): DJLXT972MBAA4
廠商: Intel Corp.
英文描述: Single-Port 10/100 Mbps PHY Transceiver
中文描述: 單端口10/100 Mbps的物理層收發(fā)器
文件頁(yè)數(shù): 41/92頁(yè)
文件大?。?/td> 666K
代理商: DJLXT972MBAA4
Intel
LXT972M Single-Port 10/100 Mbps PHY Transceiver
Datasheet
Document Number: 302875-005
Revision Date: 27-Oct-2005
41
5.6.7.2
Internal Digital Loopback (Test Loopback)
A test loopback function is provided for diagnostic testing of the LXT972M Transceiver. During
test loopback, twisted-pair and fiber interfaces are disabled. Data transmitted by the MAC is
internally looped back by the LXT972M Transceiver and returned to the MAC.
Test loopback is available for both 100BASE-TX and 10BASE-T operation, and is enabled by
setting the following register bits:
Register bit 0.14 = 1 (Setting to enable loopback mode)
Register bit 0.8 = 1 (Setting for full-duplex mode)
Register bit 0.12 = 0. (Disable auto-negotiation.)
5.7
100 Mbps Operation
5.7.1
100BASE-X Network Operations
During 100BASE-X operation, the LXT972M Transceiver transmits and receives 5-bit symbols
across the network link.
Figure 11
shows the structure of a standard frame packet in 100BASE-X mode. When the MAC is
not actively transmitting data, the LXT972M Transceiver sends out Idle symbols on the line.
As
Figure 11
shows, the MAC starts each transmission with a preamble pattern. As soon as the
LXT972M Transceiver detects the start of preamble, it transmits a Start-of-Stream Delimiter (SSD,
symbols J and K) to the network. It then encodes and transmits the rest of the packet, including the
balance of the preamble, the SFD, packet data, and CRC.
Once the packet ends, the LXT972M Transceiver transmits the End-of-Stream Delimiter (ESD,
symbols T and R) and then returns to transmitting Idle symbols.
For details on the symbols used, see 4B/5B coding listed in
Table 15, “4B/5B Coding” on page 46
.
Figure 11. 100BASE-X Frame Format
P0
P1
P6
SFD
64-Bit Preamble
(8 Octets)
Start-of-Frame
Delimiter (SFD)
DA
DA
SA
SA
Destination and Source
Address (6 Octets each)
L1
L2
Packet Length
(2 Octets)
D0
D1
Dn
Data Field
(Pad to minimum packet size)
Frame Check Field
(4 Octets)
CRC
I0
InterFrame Gap / Idle Code
(> 12 Octets)
Replaced by
/T/R/ code-groups
End-of-Stream Delimiter (ESD)
IFG
Replaced by
/J/K/ code-groups
Start-of-Stream
Delimiter (SSD)
B3466-01
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DJLXT972MBCA4 制造商:INTEL 制造商全稱:Intel Corporation 功能描述:Single-Port 10/100 Mbps PHY Transceiver
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