TXC-06880BIOG Transwitch Corporation, TXC-06880BIOG Datasheet - Page 64

• 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 4 o f 12 2
6.2.1.3 Input SPI-3 Interface Frame Format:
counted. The only difference between Store and Forward mode and Streaming mode when
Oversubscription is being used is in the treatment of the packet that overflows the Egress
FIFO. In Store and Forward mode, the overflowing packet will be discarded and counted. In
Streaming mode, the overflowing packet will be flagged as errored into the Egress FIFO and
it will be errored on the way out of the Transmit MAC.
In PHY Layer mode, Oversubscription is always enabled. STPA/PTPA status is always
presented accurately on the external SPI-3 port.
In Link Layer mode, Oversubscription can be enabled or disabled through the
Oversubscription Enable bit (Register 0x002C Bit 4). If the Oversubscription enable bit is set
to ‘1’, the SPI-3 Master will never raise its ISPIRENB output. Setting this bit shuts off all Rx
backpressure reporting from the Envoy-CE2. If the Oversubscription enable bit is set to ‘0’,
the SPI-3 Master uses the ISPIRENB output pin to exert standard SPI-3 backpressure.
The Data format accepted by Envoy-CE2, at the SPI-3 Input interface, is an Ethernet frame
(VLAN frames also), excluding the preamble and the Start of frame delimiter. If the Transmit
MAC is configured to generate the Frame Check Sequence (FCS), then the FCS is optional for
the frame received by the Envoy-CE2 at the SPI-3 interface. If the Transmit MAC is not
configured to generate the FCS, then the FCS needs to be included in the frame.
Standard Ethernet Frame at SMII/GMII Transmit interface
Frame format at the SPI-3 Input Interface with Frame Check Sequence
Frame format at the SPI-3 Input Interface without Frame Check Sequence
VLAN Tagged and Extended frames may have the FCS included depending whether
Envoy-CE2 is configured to generate FCS or not.
Preamble
(7 bytes)
Destination
(6 bytes)
Address
Delimiter
(1 byte)
Start of
Frame
(6 bytes)
Address
Destination
Source
Destination
-
(6 bytes)
Address
(6 bytes)
Address
Operation
-
Length/Type
(2 bytes)
(6 bytes)
Address
Source
(6 bytes)
Address
Source
(2 bytes)
Length/
(46 to 1500 bytes)
Type
Length/Type
(2 bytes)
PRELIMINARY TXC-06880-MB, Ed. 4
Data
(46 to 1500
bytes)
Data
(46 to 1500 bytes)
Frame Check
Sequence
Data
(4 bytes)
Sequence
February 2005
(4 bytes)
Frame
Check