Information

Enhanced Three-Speed Ethernet Controllers
MPC8308 PowerQUICC II Pro Processor Reference Manual, Rev. 1
16-66 Freescale Semiconductor
16.5.3.5.2 MAC Configuration 2 Register (MACCFG2)
The MACCFG2 register is written by the user. Figure 16-36 describes the definition for the MACCFG2
register.
Table 16-40 describes the fields of the MACCFG2 register.
Offset eTSEC1:0x2_4504; eTSEC2:0x2_5504 Access: Read/Write
0 15
R
—
W
Reset All zeros
16 19 20 21 22 23 24 25 26 27 28 29 30 31
R
Preamble
Length
—
I/F
Mode
PreAmRxEN PreAmTxEN
Huge
Frame
Length
check
— PAD/CRC CRC EN
Full
Duplex
W
Reset011100000 0 000 0 00
Figure 16-36. MACCFG2 Register Definition
Table 16-40. MACCFG2 Field Descriptions
Bits Name Description
0–15 — Reserved
16–19 Preamble
Length
This field determines the length in bytes of the preamble field preceding each Ethernet start-of-frame
delimiter byte. Values from 0x3 to 0xF are supported by the controller. The default value of 0x7 should
not be altered in order to guarantee reliable operation with IEEE 802.3 compliant hardware.
20–21 — Reserved
22–23 I/F Mode This field determines the type of interface to which the MAC is connected. Its default is 00.
00 Reserved bit mode (not supported) (10 Mbps GENDEC/GPSI)
01 Nibble mode (MII, RGMII) (10/100 Mbps MII, RGMII). For RGMII, ECNTRL.RPM should be set to 1.
10 1000 Mbps RGMII
11 Reserved
24 PreAM RxEN User defined preamble enable for received frames. This bit is cleared by default.
0 The MAC skips the Ethernet preamble without returning it.
1 The MAC recovers the received Ethernet preamble and passes it to the driver at the start of each
received frame. If the preamble is less than 7 bytes, 0s are prepended to pad it to 7 bytes.
25 PreAM TxEN User defined preamble enable for transmitted frames. This bit is cleared by default.
0 The MAC generates a standard Ethernet preamble.
1 If a user-defined preamble has been passed to the MAC it is transmitted instead of the standard
preamble. Otherwise the standard Ethernet preamble is generated. The Preamble Length field
should be left at its default setting if a user-defined preamble is transmitted.