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Fast Ethernet Controllers (FEC0 and FEC1)
26-47
Freescale Semiconductor
26.5.15 RMII Loopback
The FEC also supports RMII loopback. In this mode, transmit data is sent to the RMII receive logic and
out the FEC_TXD[1:0] pins. To enable RMII loopback mode, set RCR [RMII_MODE, RMII_LOOP] and
TCR [FDEN] and clear RCR [RMII_ECHO, LOOP].
Figure 26-29. RMII Loopback Mode
26.5.16 RMII Echo
The ethernet controller also supports RMII echo mode, which transmits data on FEC_TXD[1:0] as it is
received on FEC_RXD[1:0]. To enable RMII echo mode, set RCR [RMII_MODE, RMII_ECHO] bits and
clear RCR [RMII_LOOP, LOOP].
Figure 26-30. RMII Echo Mode
26.5.17 Ethernet Error-Managing Procedure
The Ethernet controller reports frame reception and transmission error conditions using the MIB block
counters, the FEC RxBDs, and the EIR
n
register.
26.5.17.1 Transmission Errors
26.5.17.1.1
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, and EIR
n
[UN] is set. The FEC then continues to the
next transmit buffer descriptor and begin transmitting the next frame. The UN interrupt is asserted if
enabled in the EIMR
n
register.
n
n
n
TX
RX
RMII
Transmit
Receive
FEC
FEC_TXD[1:0]
n
n
TX
RX
RMII
Transmit
Receive
FEC
FEC_TXD[1:0]
FEC_RXD[1:0]
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...