Altera Triple Speed Ethernet MegaCore Function - Manual (Page 62)

Figure 4-15: 1000BASE-X/SGMII PCS with Embedded PMA
SGMII
Receive
Converter
SGMII
Transmit
Converter
Configuration
Encapsulation
De -encapsulation
&
Synchronization
Auto-Negotiation
Status
LEDs
Avalon -MM Interface
MII/GMII
Receive
MII/GMII
Transmit
Serializer
PMA
PHY
Loopback
Ethernet Side MAC Side
1000 Base-X PCS Receive Control
1000 Base-X PCS Transmit Control
8b/10b
Decoder
8b/10b
Encoder
1.25 Gbps
Serial Receive
1.25 Gbps
Serial Transmit
1000BASE-X/SGMII PCS with PMA
CDR &
Deserializer
Transmit Operation
The transmit operation includes frame encapsulation and encoding.
Frame Encapsulation
The PCS function replaces the first preamble byte in the MAC frame with the start of frame /S/ symbol.
Then, the PCS function encodes the rest of the bytes in the MAC frame with standard 8B/10B encoded
characters. After the last FCS byte, the PCS function inserts the end of frame sequence, /T/ /R/ /R/ or /T/
/R/, depending on the number of character transmitted. Between frames, the PCS function transmits /I/
symbols.
If the PCS function receives a frame from the MAC function with an error (
gm_tx_err
asserted during frame
transmission), the PCS function encodes the error by inserting a /V/ character.
8b/10b Encoding
The 8B/10B encoder maps 8-bit words to 10-bit symbols to generate a DC balance and ensure disparity of
the stream with a maximum run length of 5.
Functional Description Altera Corporation
Send Feedback
UG-01008
Transmit Operation 4-26
2014.06.30