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Fast Ethernet Controllers (FEC0 and FEC1)
26-37
Freescale Semiconductor
The 7-wire serial mode interface (RCR
n
[MII_MODE] cleared and RCR [RMII_MODE] cleared or set)
is generally referred to as AMD mode.
shows the 7-wire mode connections to the external
transceiver.
26.5.7
FEC Frame Transmission
The Ethernet transmitter is designed to work with almost no intervention from software. After
ECR
n
[ETHER_EN] is set and data appears in the transmit FIFO, the Ethernet MAC can transmit onto the
network. The Ethernet controller transmits bytes least significant bit (lsb) first.
When the transmit FIFO fills to the watermark (defined by TFWR
n
), MAC transmit logic asserts
FEC
n
_TXEN and starts transmitting the preamble (PA) sequence, the start frame delimiter (SFD), and
then the frame information from the FIFO. However, the controller defers the transmission if the network
is busy (FEC
n
_CRS is asserted). Before transmitting, the controller waits for carrier sense to become
inactive, then determines if carrier sense stays inactive for 60 bit times. If so, transmission begins after
waiting an additional 36 bit times (96 bit times after carrier sense originally became inactive). See
Section 26.5.17.1, “Transmission Errors,”
for more details.
Table 26-36. RMII Mode Configuration
Signal Description
EMAC Pin
Reference Clock
FEC
n
_
TXCLK
Transmit Enable
FEC
n
_
TXEN
Transmit Data
FEC
n
_
TXD[1:0]
Receive Data Valid
FEC
n
_
RXDV
Receive Data
FEC
n
_
RXD[1:0]
Receive Error
FEC
n
_RXER
Table 26-37. 7-Wire Mode Configuration
Signal description
EMAC Pin
Transmit Clock
FEC
n
_
TXCLK
Transmit Enable
FEC
n
_
TXEN
Transmit Data
FEC
n
_
TXD[0]
Collision
FEC
n
_
COL
Receive Clock
FEC
n
_
RXCLK
Receive Data Valid
FEC
n
_
RXDV
Receive Data
FEC
n
_
RXD[0]
n
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 ...