Fast Ethernet Controller (FEC)
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
45-9
45.2.10.1 Transmission Errors
Table 45-4
describes transmission errors.
45.2.10.2 Reception Errors
Table 45-5
describes reception errors.
45.2.11 SDMA Bus Arbitration and Transfers
There are two arbitration levels to consider—accesses to the SDMA hardware and accesses to the U-bus.
As shown in
Figure 45-3
, if the CPM and the 100BASE-T module attempt to access the SDMA
Table 45-4. Transmission Errors
Error
Description
Transmitter
Underrun
If this error occurs, the FEC sends 32 bits that ensure a CRC error and stops transmitting. All
remaining buffers for that frame are then flushed and closed, with the UN bit set in the last TxBD for
that frame. The FEC continues to the next TxBD and begins transmitting the next frame.
Carrier Sense
Lost during
Frame
Transmission
When this error occurs and no collision is detected in the frame, the FEC sets the CSL bit in the last
TxBD for this frame. The frame is sent normally. No retries are performed as a result of this error.
The CSL bit is not set if X_CNTRL[FDEN] = 1, regardless of the state of CRS.
Retransmission
Attempts Limit
Expired
When this error occurs, the FEC terminates transmission. All remaining buffers for that frame are
then flushed and closed, with the RL bit set in the last TxBD for that frame. The FEC then continues
to the next TxBD and begins sending the next frame.
Late Collision
When this error occurs, the FEC stops sending. All remaining buffers for that frame are then flushed
and closed, with the LC bit set in the last TxBD for that frame. The FEC then continues to the next
TxBD and begins sending the next frame.
Note: The definition of what constitutes a late collision is hard-wired in the FEC.
Heartbeat
Some transceivers have a self-test feature called heartbeat or signal-quality error. To signify a good
self-test, the transceiver indicates a collision within 20 clocks after the FEC sends a frame. This
heartbeat condition does not imply a real collision, but that the transceiver seems to work properly.
If X_CNTRL[HBC] = 1, X_CNTRL[FDEN]=0, and a heartbeat condition is not detected after a frame
transmission, a heartbeat error occurs—the FEC closes the buffer, sets TxBD[HB], and generates
the HBERR interrupt if it is enabled.
Table 45-5. Reception Errors
Error
Description
Overrun Error
The FEC maintains an internal FIFO for receiving data. If a receiver FIFO overrun occurs, the FEC
closes the buffer and sets RxBD[OV].
Non-Octet Error
(Dribbling Bits)
The FEC handles up to seven dribbling bits when the receive frame terminates nonoctet aligned and
it checks the CRC of the frame on the last octet boundary. If there is a CRC error, the frame nonoctet
aligned (NO) error is reported in the RxBD. If there is no CRC error, no error is reported.
CRC Error
When a CRC error occurs with no dribbling bits, the FEC closes the buffer and sets RxBD[CR]. CRC
checking cannot be disabled, but the CRC error can be ignored if checking is not required.
Frame Length
Violation
When the receive frame length exceeds R_HASH[MAX_FRAME_LENGTH], I_EVENT[BABR] is set
indicating babbling receive error, and the LG bit in the end of frame RxBD is set.
Note: Receive frames exceeding 2047 bytes are truncated.
Содержание PowerQUICC MPC870
Страница 1: ...MPC885 PowerQUICC Family Reference Manual Supports MPC885 MPC880 MPC875 MPC870 MPC885RM Rev 2 04 2006 ...
Страница 98: ...MPC885 PowerQUICC Family Reference Manual Rev 2 I 4 Freescale Semiconductor ...
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 ...
Страница 288: ...MPC885 PowerQUICC Family Reference Manual Rev 2 III 4 Freescale Semiconductor ...
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 ...
Страница 1336: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 16 Freescale Semiconductor ...
Страница 1358: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 38 Freescale Semiconductor ...
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 ...