TXC-06880BIOG Transwitch Corporation, TXC-06880BIOG Datasheet - Page 66

• 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

Envoy-CE2 Device
DATA SHEET
TXC-06880
6 6 o f 12 2
6.2.3 Transmit MAC Data Flow
6.2.2.2 Egress FIFO Frame Availability for Transfer (Store and Forward/Streaming):
6.2.2.3 Egress FIFO Read:
Frame data stored in the Egress FIFO will be made available for transfer on the Ethernet
Transmit interface, depending on two selectable modes of operation:
Frame data from the Egress FIFO is read out by the Transmit MAC block. Each channel has
an SMII/GMII Transmit block and interfaces to the appropriate Egress FIFO. When a
complete frame or a programmed number of bytes have been written into the Egress FIFO,
then it is available for transmission on the Ethernet Network via the SMII/GMII Transmit
interface.
The Egress FIFO forms an integral part in the implementation of the IEEE 802.3 compliant
Ethernet flow control mechanism in the Envoy-CE2, using PAUSE Control frames. When a
PAUSE Control frame destined for the Envoy-CE2 reaches the SMII/GMII receive interface,
the action taken by the Full-Duplex flow control block is to stop Egress FIFO reads. This may
result in the Egress FIFO becoming full. As mentioned above, the SPI-3 interface is
backpressured when the Egress FIFO becomes full. A complete explanation of the Full-
Duplex Ethernet flow control mechanism is outlined in section
page
The MAC can be configured to operate in either Full-Duplex mode or Half Duplex mode (Fast
Ethernet only). The MAC transmits both standard Ethernet frames 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 Egress FIFO indicates availability of a
Frame to the Transmit MAC when a complete frame is stored in the Egress FIFO. The
Transmit MAC reads the Egress FIFO and transmits the frame over the SMII/GMII transmit
interface.
71.
• Store and Forward Mode: When a complete frame has been written into the Egress
• Streaming Mode: When a selectable fixed number of bytes have been written into
FIFO, the frame is available for transfer to the Ethernet transmit interface (SMII/
GMII).
the Egress FIFO, a frame is available for transfer. The selections for streaming are
64, 128, 256, 512, 768, or 1544 bytes. When streaming is enabled and an end of
frame is written into the Egress FIFO, before the selected number of (streaming)
bytes have been received, the frame data will be available for transfer across the
Ethernet transmit interface (SMII/GMII) based on the end of frame condition. When
streaming is enabled, frame errors at the SPI-3 interface are indicated on the SMII/
GMII interface during the transfer of the frame.
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Operation
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PRELIMINARY TXC-06880-MB, Ed. 4
“Ethernet Full Duplex” on
February 2005