TXC-06880BIOG Transwitch Corporation, TXC-06880BIOG Datasheet - Page 59

• Manufacturer Part Number: TXC-06880BIOG
• Manufacturer: Transwitch Corporation

Specifications of TXC-06880BIOG

• Operating Supply Voltage (typ): 1.8/3.3V
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Not Compliant

PRELIMINARY TXC-06880-MB, Ed. 4
February 2005
6.1 SMII/GMII TO SPI-3 FLOW FUNCTIONAL OPERATION
6.1.1 Receive MAC Data Flow
6.1.2 Receive MAC Checks
6.1.2.1 FCS Check:
6.1.2.2 Frame Length Check:
6.1.2.3 Maximum Frame Size Check:
Ethernet frames arriving at the SMII/GMII interface are qualified by an IEEE 802.3 compliant
Media Access Controller (MAC) function. Each SMII/GMII interface or each channel is
processed by the MAC. The MAC operates in Full-Duplex or Half-Duplex mode and
processes both standard and VLAN tagged Ethernet frames. The MAC supports Control
frames in addition to PAUSE control frames per the IEEE 802.3 standard (Generation and
Termination). The SMII/GMII interface presents receive frames to the MAC receive block and
the MAC removes the PREAMBLE and the SFD (Start of Frame Delimiter) and writes the
frames into the appropriate Ingress FIFO.
Following are the checks performed by the MAC if enabled, for each port on the incoming
Ethernet frame.
The Frame Check Sequence (FCS) is checked for its correctness. The FCS of the received
frame is checked against the FCS calculated by the MAC over the Data, address, and length/
type fields. Frames failing the FCS check are optionally discarded based on a programmable
bit in the configuration register. This configuration bit is the FCS check failed discard bit.
When the IFIFO is configured for Store and Forward mode, the frame is discarded and will
not show up on the SPI port. When the IFIFO is configured for Streaming mode, a bad FCS is
appended to the frame.
The length field of the received Ethernet frame is checked for correctness. The length of the
Data field in the Ethernet frame is checked against the frame length field. The Frame length
check enable bit is programmable (Register 0x4004 Bit 4). Frames failing the frame length
check will be optionally discarded or errored if the frame length check discard configuration
bit is set (Register 0x4084 Bit 25).
When the IFIFO is configured for Store and Forward mode, the frame is discarded and will
not show up on the SPI port. When the IFIFO is configured for Streaming mode, a bad FCS is
appended to the frame.
The maximum size of the accepted Ethernet frame is programmable. The default value is
1536 (decimal) bytes. Frames exceeding the programmed maximum frame size are
- Operation -
6.0 O
Envoy-CE2 Device
PERATION
DATA SHEET
TXC-06880
59 o f 12 2