SCC Ethernet Mode
MPC885 PowerQUICC Family Reference Manual, Rev. 2
27-2
Freescale Semiconductor
and total frame length to 1,518 bytes. The last 4 bytes of the frame are the frame check sequence (FCS), a
standard 32-bit CCITT-CRC polynomial used in many protocols.
When a station needs to transmit, it checks for LAN activity. When the LAN is silent for a specified period,
the station starts sending. At that time, the station continually checks for collisions on the LAN; if one is
found, the station forces a jam pattern (all ones) on its frame and stops sending. Most collisions occur close
to the beginning of a frame. The station waits a random period of time, called a backoff, before trying to
retransmit. Once the backoff time expires, the station waits for silence on the LAN before retransmitting,
which is called a retry. If the frame cannot be sent within 15 retries, an error occurs.
10-Mbps ethernet transmits at 0.8 µs per byte. The preamble plus start frame delimiter is sent in 6.4 µs.
The minimum 10-Mbps ethernet interframe gap is 9.6 µs and the slot time is 52 µs.
27.1
Ethernet on the MPC885
Setting GSMR[MODE] to 0b1100 selects ethernet. The SCC performs the full set of IEEE 802.3/ethernet
CSMA/CD media access control and channel interface functions.
Figure 27-2
shows the ethernet block
diagram.
Figure 27-2. Ethernet Block Diagram
The MPC885 ethernet controller requires an external serial interface adaptor (SIA) and transceiver
function to complete the interface to the media. This function is implemented in the Motorola MC68160
enhanced ethernet serial transceiver (EEST).
The MPC885 and EEST solution provides a direct connection to the attachment unit interface (AUI) or
twisted-pair (10BASE-T). The EEST provides a glueless interface to the MPC885, Manchester encoding
and decoding, automatic selection of 10BASE-T versus AUI ports, 10BASE-T polarity detection and
correction. The MC68160 documentation gives more information.
SHIFTER
RX
RECEIVER
CONTROL
UNIT
FIFO
SHIFTER
TX
TRANSMITTER
CONTROL
UNIT
FIFO
SLOT TIME
CLOCK
GENERATOR
INTERNAL CLOCKS
CONTROL
REGISTERS
TXD
RXD
PERIPHERAL BUS
DATA
DATA
RCLK
TCLK
AND DEFER
COUNTER
RTS = TENA
RA
N
D
O
M
NO
.
CD = RENA
CTS = CLSN
CTS = CLSN
CD = RENA
REJECT
RSTRT
U-BUS
Содержание PowerQUICC MPC870
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Страница 118: ...MPC885 Overview MPC885 PowerQUICC Family Reference Manual Rev 2 1 20 Freescale Semiconductor ...
Страница 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
Страница 192: ...MPC885 Instruction Set MPC885 PowerQUICC Family Reference Manual Rev 2 5 22 Freescale Semiconductor ...
Страница 242: ...Instruction and Data Caches MPC885 PowerQUICC Family Reference Manual Rev 2 7 30 Freescale Semiconductor ...
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Страница 416: ...External Bus Interface MPC885 PowerQUICC Family Reference Manual Rev 2 13 42 Freescale Semiconductor ...
Страница 440: ...Clocks and Power Control MPC885 PowerQUICC Family Reference Manual Rev 2 14 24 Freescale Semiconductor ...
Страница 554: ...MPC885 PowerQUICC Family Reference Manual Rev 2 V 6 Freescale Semiconductor ...
Страница 606: ...SDMA Channels and IDMA Emulation MPC885 PowerQUICC Family Reference Manual Rev 2 19 20 Freescale Semiconductor ...
Страница 738: ...SCC Asynchronous HDLC Mode and IrDA MPC885 PowerQUICC Family Reference Manual Rev 2 25 16 Freescale Semiconductor ...
Страница 780: ...SCC Ethernet Mode MPC885 PowerQUICC Family Reference Manual Rev 2 27 24 Freescale Semiconductor ...
Страница 794: ...SCC Transparent Mode MPC885 PowerQUICC Family Reference Manual Rev 2 28 14 Freescale Semiconductor ...
Страница 848: ...Serial Peripheral Interface SPI MPC885 PowerQUICC Family Reference Manual Rev 2 30 18 Freescale Semiconductor ...
Страница 882: ...Universal Serial Bus USB MPC885 PowerQUICC Family Reference Manual Rev 2 31 34 Freescale Semiconductor ...
Страница 944: ...Parallel I O Ports MPC885 PowerQUICC Family Reference Manual Rev 2 34 26 Freescale Semiconductor ...
Страница 956: ...CPM Interrupt Controller MPC885 PowerQUICC Family Reference Manual Rev 2 35 12 Freescale Semiconductor ...
Страница 1004: ...Buffer Descriptors and Connection Tables MPC885 PowerQUICC Family Reference Manual Rev 2 37 30 Freescale Semiconductor ...
Страница 1022: ...ATM Parameter RAM MPC885 PowerQUICC Family Reference Manual Rev 2 38 18 Freescale Semiconductor ...
Страница 1068: ...ATM Pace Control MPC885 PowerQUICC Family Reference Manual Rev 2 40 22 Freescale Semiconductor ...
Страница 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Страница 1120: ...AAL2 Implementation MPC885 PowerQUICC Family Reference Manual Rev 2 44 30 Freescale Semiconductor ...
Страница 1162: ...Fast Ethernet Controller FEC MPC885 PowerQUICC Family Reference Manual Rev 2 45 40 Freescale Semiconductor ...
Страница 1172: ...SEC Lite Overview MPC885 PowerQUICC Family Reference Manual Rev 2 46 8 Freescale Semiconductor ...
Страница 1176: ...SEC Lite Address Map MPC885 PowerQUICC Family Reference Manual Rev 2 47 4 Freescale Semiconductor ...
Страница 1214: ...SEC Lite Execution Units MPC885 PowerQUICC Family Reference Manual Rev 2 48 38 Freescale Semiconductor ...
Страница 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
Страница 1313: ...MPC885 PowerQUICC Family Reference Manual Rev 2 Freescale Semiconductor B 1 Appendix B Serial Communications Performance TBD ...
Страница 1314: ...Serial Communications Performance MPC885 PowerQUICC Family Reference Manual Rev 2 B 2 Freescale Semiconductor ...
Страница 1320: ...Register Quick Reference Guide MPC885 PowerQUICC Family Reference Manual Rev 2 C 6 Freescale Semiconductor ...
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Страница 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
Страница 1384: ...Serial ATM Scrambling Reception and SI Programming MPC885 PowerQUICC Family Reference Manual Rev 2 H 6 Freescale Semiconductor ...
Страница 1386: ...Revision History MPC885 PowerQUICC Family Reference Manual Rev 2 I 2 Freescale Semiconductor ...