DS33Z41 Quad IMUX Ethernet Mapper
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Figure 8-15. X.86 Encapsulation of the MAC field
Flag(0x7E)
Address(0x04)
Control(0x03)
1st Octect of SAPI(0xfe)
2nd Octect of SAPI(0x01)
Destination Adrs(DA)
Source Adrs(SA)
Length/Type
Number of Bytes
1
1
1
1
1
6
6
2
MAC Client Data
46-1500
PAD
FCS for MAC
4
FCS for LAPS
Flag(0x7E)
4
MSB
LSB
The DS33Z41 will encode the MAC Frame with the LAPS encapsulation on a complete serial stream if configured
for X.86 mode in the register
LI.TX86E
. The DS33Z41 provides the following functions:
•
Control Registers for Address, SAPI, Destination Address, Source Address.
•
32 bit FCS enabled.
•
Programmable X
43
+1 scrambling.
The sequence of processing performed by the receiver is as follows:
•
Programmable octets X
43
+1 descrambling.
•
Detect the Start Flag (7E).
•
Remove Rate adaptation octets 7d, dd.
•
Perform transparency-processing 7d, 5e is converted to 7e and 7d, 5d is converted to 7d.
•
Check for a valid Address, Control and SAPI fields (
LI.TRX86A
to
LI.TRX86SAPIL
).
•
Perform FCS checking.
•
Detect the closing flag.