AN983B Datasheet, PDF (65/91 Pages) List of Unclassifed Manufacturers – PCI/miniPCI-to-Ethernet LAN Controller

AN983B PCI/miPCI Fast Ethernet Controller with integrated PHY
8.5 NETWORK OPERATION
8.5.1 MAC OPERATION
In the MAC (Media Access Control) portion of AN983B, it incorporates the essential protocol
requirements for operating as an IEEE802.3 and Ethernet compliant node.
Format
Field
Description
Preamble
A 7-byte field of (10101010b)
Start Frame Delimiter
A 1-byte field of (10101011b)
Destination Address
A 6-byte field
Source Address
A 6-byte field
Length/Type
A 2-byte field indicated the frame is in IEEE802.3 format or Ethernet
format.
IEEE802.3 format: 0000H ~ 05DCH for Length field
Ethernet format: 05DD ~ FFFFH for Type field
Data
*46 ~ 1500 bytes of data information
CRC
A 32-bit cyclic redundant code for error detection
*Note: If padding is disabled (TDES1 bit23), the data field may be shorter than 46 bytes.
Transmit Data Encapsulation
The differences between the encapsulation and a MAC frame while operating in the
100BASE-TX mode are listed as follow:
1. The first byte of the preamble is replaced by the JK code according to the IEE802.3u,
clause 24.
2. After the CRC field of the MAC frame, the AN983B insert the TR code according to the
IEE802.3u, clause 24.
Receive Data Decapsulation
When operate in 100BASE-TX mode the AN983B detects a JK code for a preamble as well
as a TR code for the packet end. If a JK code is not detected, the AN983B will abort this
frame receiving and wait for a new JK code detection. If a TR code is not detected, the
AN983B will report a CRC error.
Deferring
The Inter-Frame Gap (IFG) time is divided into two parts:
Rev. 1.8
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