QUICC Engine Subsystem
MSC8144E Reference Manual, Rev. 3
Freescale Semiconductor
1-23
10/100 Mbps RMII (consortium standard)
10/100 Mbps SMII
1000 Mbps SGMII with SerDes support
10/100/1000 Mbps RGMII (full duplex only)
The media-independent interface (MII) provides a standard interface between the MAC layer and
the physical layer. It isolates the MAC layer and the physical layer so that the MAC layer can be
used with various physical layer implementations. The RMII interface (a reduced pin count MII)
is specified by the RMII Consortium standard as a low cost alternative to the MII, using 8 pins
instead of 16 (excluding the
MDC
and
MDIO
signals). The SMII interface further reduces the pin
count to 6 signals per port (excluding the
MDC
and
MDIO
signals), which greatly simplifies switch
design and reduces board space and overall design and layout costs.
The Ethernet transmitter requires little core intervention. After the software driver initializes the
system, the Ethernet controller activates its transmit scheduler. As a result, the controller starts
polling the first transmit buffer descriptor (TxBD) in one of the eight transmit queues as chosen
by the scheduler. The TxBD ring is polled every 512 transmit clocks. If TxBD[R] bit is set, the
Ethernet controller begins moving transmit buffers from memory to the Tx virtual FIFO. The
Ethernet MAC transmitter takes data from Tx virtual FIFO and transmits the data through the
appropriate interface (RGMII/SGMII/RMII/SMII) to the physical media. The transmitter, once
initialized, runs until the end-of-frame (EOF) condition is detected, unless a collision within the
collision window occurs (in half-duplex mode) or an abort condition is encountered. The
Ethernet Controller receiver can perform pattern matching, data extraction, Ethernet type
recognition, CRC checking, VLAN detection, short frame checking, and maximum frame-length
checking.
After a hardware reset, the software driver initializes the parameter RAM and the configuration
register, and then sets MACCFG1[RX_EN]. The Ethernet receiver is enabled and immediately
starts processing receive frames. The MAC hardware checks when
RX_DV
is asserted and as long
as
COL
remains deasserted (full-duplex mode ignores
COL
), it looks for the start of a frame by
searching for a valid preamble/SFD (start of frame delimiter) header, which is stripped and the
frame begins to be processed. If a valid header is not found, the frame is ignored. Part of the
preamble is user configurable, to allow for user configurable preamble.
If the receiver detects the first bytes of a frame, the Ethernet Controller begins to perform the
frame recognition function. Two modes are supported: MSC8122/MSC8126
backward-compatible frame filtering, and extended frame filtering mode. The Extended filtering
supports large memory based lookup tables, thus replacing the need for an external CAM device.
In MSC8122/MSC8126 mode, the receiver can also filter frames based on physical (individual),
group (multicast), and broadcast addresses. If a frame is accepted, the Ethernet controller fetches
a receive buffer descriptor (RxBD) from FIFO. If RxBD is not being used by the software
(RxBD[E] is set), the controller starts transferring the incoming frame. RxBD[F] is set for the
first RxBD used for any particular receive frame. When the buffer is filled, the Ethernet
Summary of Contents for MSC8144E
Page 1: ...MSC8144E Reference Manual Quad Core Media Signal Processor MSC8144ERM Rev 3 July 2009 ...
Page 48: ...MSC8144E Reference Manual Rev 3 xlviii Freescale Semiconductor ...
Page 86: ...MSC8144E Reference Manual Rev 3 1 38 Freescale Semiconductor Overview ...
Page 168: ...MSC8144E Reference Manual Rev 3 3 60 Freescale Semiconductor External Signals ...
Page 242: ...MSC8144E Reference Manual Rev 3 5 26 Freescale Semiconductor Reset ...
Page 314: ...MSC8144E Reference Manual Rev 3 8 24 Freescale Semiconductor General Configuration Registers ...
Page 414: ...MSC8144E Reference Manual Rev 3 10 14 Freescale Semiconductor MSC8144E SC3400 DSP Subsystem ...
Page 452: ...MSC8144E Reference Manual Rev 3 11 38 Freescale Semiconductor Internal Memory Subsystem ...
Page 520: ...MSC8144E Reference Manual Rev 3 12 68 Freescale Semiconductor DDR SDRAM Memory Controller ...
Page 1070: ...MSC8144E Reference Manual Rev 3 21 28 Freescale Semiconductor Timers ...