Functional Description; Mac Operation; Ethernet Mac Block Diagram; Ethernet Frame - Texas Instruments Concerto F28M35 Series Technical Reference Manual

Functional Description

19.3 Functional Description
The functional description of the EMAC is discussed in the following sections.

19.3.1 MAC Operation

The following sections describe the operation of the MAC layer, including an overview of the Ethernet
frame format, the MAC layer FIFOs, Ethernet transmission, reception options, packet timestamps, and
Ethernet MAC address format.
19.3.1.1 Ethernet Frame Format
Ethernet data is carried by Ethernet frames. The basic frame format is shown in
Preamble
7
Bytes
The seven fields of the frame are transmitted from left to right. The bits within the frame are transmitted
from least to most significant bit.
• Preamble
The Preamble field is used to synchronize with the received frame's timing. The preamble is 7 octets
long.
• Start Frame Delimiter (SFD)
The SFD field follows the preamble pattern and indicates the start of the frame. Its value is
1010.1011b.
• Destination Address (DA)
This field specifies destination addresses for which the frame is intended. The LSB (bit 16 of DA oct 1
in the frame, see Table 18-3 on page 907) of the DA determines whether the address is an individual
(0), or group/multicast (1) address.
1382
M3 Ethernet Media Access Controller (EMAC)
Figure 19-2. Ethernet MAC Block Diagram
Interrupt
Interrupt
Control
MACRIS
MACIACK
MACIM
Timer
Support
MACTS
Individual
Address
MACIA0
MACIA1
Figure 19-3. Ethernet Frame
SFD Destination Address Source Address
1 6
Byte Bytes
Copyright © 2012–2019, Texas Instruments Incorporated
Receive
Control
Transmit
MACRCTL
FIFO
MACNP
Data
Access
MACDDATA
Transmit
Receive
Control
FIFO
MACTCTL
MACTHR
MACTR
MII
Control
MACMCTL
MACMDV
MACMTXD
MACMRXD
Length/
Type
6 2
Bytes Bytes
SPRUH22I – April 2012 – Revised November 2019
www.ti.com
Figure 19-3.
Data FCS
46 -1500 4
Bytes Bytes
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