MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
27-1
Chapter 27
SCC Ethernet Mode
This chapter describes SCC ethernet functionality as specifically implemented on the MPC885. To ensure
proper implementation of other derivatives of the MPC885 family,
Table 27-1
is provided as a quick
reference of the fundamental differences. The appropriate appendix should be consulted for further
information.
The ethernet IEEE 802.3 protocol is a widely used LAN protocol based on the carrier sense multiple
access/collision detect (CSMA/CD) approach. Because ethernet and IEEE 802.3 protocols are similar and
can coexist on the same LAN, both are referred to as ethernet in this manual, unless otherwise noted.
Figure 27-1
shows ethernet and IEEE 802.3 frame structure.
Figure 27-1. Ethernet Frame Structure
The frame begins with a 7-byte preamble of alternating ones and zeros. Because the frame is Manchester
encoded, the preamble gives receiving stations a known pattern on which to lock. The start frame delimiter
follows the preamble, signifying the beginning of the frame. The 48-bit destination address is next,
followed by the 48-bit source address. Original versions of the IEEE 802.3 specification allowed 16-bit
addressing, but this addressing has never been widely used and is not supported.
The next field is the ethernet type field/IEEE 802.3 length field. The type field signifies the protocol used
in the rest of the frame and the length field specifies the length of the data portion of the frame. For ethernet
and IEEE 802.3 frames to coexist on the same LAN, the length field of the frame must always be different
from any type fields used in ethernet. This limits the length of the data portion of the frame to 1,500 bytes
Table 27-1. MPC885 Family
Part
SCC Ethernet
Documentation
10T
MPC885
Up to 3
This manual
MPC880
Up to 2
Appendix E
MPC875
1
Appendix F
MPC870
0
Appendix G
Preamble
Start Frame
Data
Delimiter
Destination
Address
Type/
Length
Source
Address
Frame Check
Sequence
7 Bytes
1 Byte
6 Bytes
6 Bytes
2 Bytes
46–1500 Bytes
4 Bytes
Frame Length is
Note: The lsb of each octet is transmitted first.
64–1518 Bytes
Summary of Contents for PowerQUICC MPC870
Page 98: ...MPC885 PowerQUICC Family Reference Manual Rev 2 I 4 Freescale Semiconductor ...
Page 118: ...MPC885 Overview MPC885 PowerQUICC Family Reference Manual Rev 2 1 20 Freescale Semiconductor ...
Page 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
Page 288: ...MPC885 PowerQUICC Family Reference Manual Rev 2 III 4 Freescale Semiconductor ...
Page 554: ...MPC885 PowerQUICC Family Reference Manual Rev 2 V 6 Freescale Semiconductor ...
Page 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Page 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
Page 1336: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 16 Freescale Semiconductor ...
Page 1358: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 38 Freescale Semiconductor ...
Page 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
Page 1386: ...Revision History MPC885 PowerQUICC Family Reference Manual Rev 2 I 2 Freescale Semiconductor ...