Ethernet

Ethernet

The Ethernet block contains a full featured 10 Mbit/s or 100 Mbit/s Ethernet MAC
designed to provide optimized performance through the use of DMA hardware
acceleration. Features include a generous suite of control registers, half or full duplex
operation, flow control, control frames, hardware acceleration for transmit retry, receive
packet filtering and wake-up on LAN activity. Automatic frame transmission and reception
with scatter-gather DMA off-loads many operations from the CPU.
The Ethernet block and the CPU share a dedicated AHB subsystem that is used to access
the Ethernet SRAM for Ethernet data, control, and status information. All other AHB traffic
in the LPC2387 takes place on a different AHB subsystem, effectively separating Ethernet
activity from the rest of the system. The Ethernet DMA can also access the USB SRAM if
it is not being used by the USB block.
The Ethernet block interfaces between an off-chip Ethernet PHY using the Reduced MII
(RMII) protocol and the on-chip Media Independent Interface Management (MIIM) serial
bus.

Features
• Ethernet standards support:
– Supports 10 Mbit/s or 100 Mbit/s PHY devices including 10 Base-T, 100 Base-TX,
100 Base-FX, and 100 Base-T4.
– Fully compliant with IEEE standard 802.3.
– Fully compliant with 802.3x full duplex flow control and half duplex back pressure.
– Flexible transmit and receive frame options.
– Virtual Local Area Network (VLAN) frame support.
• Memory management:
– Independent transmit and receive buffers memory mapped to shared SRAM.
– DMA managers with scatter/gather DMA and arrays of frame descriptors.
– Memory traffic optimized by buffering and pre-fetching.
• Enhanced Ethernet features:

– Receive filtering.
– Multicast and broadcast frame support for both transmit and receive.
– Optional automatic Frame Check Sequence (FCS) insertion with Circular
Redundancy Check (CRC) for transmit.
– Selectable automatic transmit frame padding.
– Over-length frame support for both transmit and receive allows any length frames.
– Promiscuous receive mode.
– Automatic collision back-off and frame retransmission.
– Includes power management by clock switching.
– Wake-on-LAN power management support allows system wake-up: using the
receive filters or a magic frame detection filter.
• Physical interface:
– Attachment of external PHY chip through standard RMII interface.
– PHY register access is available via the MIIM interface.