707
/
838
Nations Technologies Inc.
Tel
:
+86-755-86309900
:
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
Basic MAC frame format (unlabeled frame)
Tagged MAC frame format
Figure 25-2 MAC frame format and frame structure
Note: Except for FCS, the Ethernet controller transmits each byte in little-endian first-out order.
CRC calculation includes all bytes of frame data except preamble and SFD. The 32-bit CRC generator polynomial
of the Ethernet frame is 0x04C11DB7, and this polynomial is used for all 32-bit CRC calculations in the Ethernet
module, as shown in the following formula:
𝐺(𝑥) = 𝑥
32
+ 𝑥
26
+ 𝑥
23
+ 𝑥
22
+ 𝑥
16
+ 𝑥
12
+ 𝑥
11
+ 𝑥
10
+ 𝑥
8
+ 𝑥
7
+ 𝑥
5
+ 𝑥
4
+ 𝑥
2
+ 𝑥 + 1
25.4.2
Pin configuration (alternate) method
Table 25-1 ETH module pin configuration (alternate)
MII Signal
RMII Signal
Default
mapping
Remap 1
Remap 2
Remap 3
Pin configuration
MDC
MDC
PC1
Push-pull alternate output, high speed
(50MHz)
TXD2
-
PC2
Push-pull alternate output, high speed
(50MHz)
Tx_CLK
-
PC3
Input floating (reset state)
CRS
-
PA0
Input floating (reset state)
Rx_CLK
REF_CLK
PA1
Input floating (reset state)
MDIO
MDIO
PA2
Push-pull alternate output, high speed
(50MHz)
Preamble
SFD
Destination
address
Payload data
Length/Type
= 802.1QTAg
Type
Length/Type
Source
address
PAD
(optional)
FCS
Preamble
SFD
Destination
address
Tag control
information
PAD
(optional)
Source
address
Length/Type
Payload data
FCS
7 bytes
1 bytes
6 bytes
6 bytes
2 bytes
46-1500 bytes
4 bytes
7 bytes
1 bytes
6 bytes
6 bytes
Basic format
4 bytes
46-1500 bytes
QTag Prefix
4 bytes
2 bytes
1 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0
MSB
LSB
VLAN Identifier (VID, 12 bits)
User Priority
(3 bits)
CFI
(1 bit)
Tagged format