Functional Description
Microsemi Proprietary and Confidential UG0677 User Guide Revision 9.0 23
3.3 Transceiver PCS Interface Modes
The transceiver PMA connects with the fabric using four PCS interface modes. PMA-PCS gearing is
used in conjunction with the interface clock. The TX_CLK and RX_CLK frequency is equal to the FPGA
interface based on the data rate/(PMA-PCS width × PCS gearing). The PCS interface instantiates the
embedded transceiver and RTL blocks when the user customizes and generates the block. These
pre-defined protocol interfaces provide data, control, and status signaling to the user logic in the FPGA
fabric, including support for the following modes:
• 8b10b: encoding/decoding and word aligner.
• 64b6xb: 64b/66b or 64/67b encoding/decoding with gearbox logic.
• PIPE: a PHY interface for PCI Express (PIPE) supporting PCIe Gen2. Used with the embedded
PCIe core or with the soft-IP hosted in the fabric. See UG0685: PolarFire FPGA PCI Express User
Guide for details about the embedded PCIe core solution. This interface is transparent with the PCIE
(PCIESS) core.
• PMA only: direct access to the PMA without any encoding or decoding.
3.3.1 8b10b
The 8b10b mode supports the encoder and decoder only for interface widths of 16, 32, and 64 bits at the
PMA.
The following features are supported in the 8b10b:
• Transmit encoding.
• Transmit disparity forcing.
• Transmit disparity adaptation, which operates in two sub-modes—1Gbps IEEE 802.3 mode and
Fiber Channel mode.
• Receiver symbol alignment using CDR slip mechanism.
• Deterministic latency through the 8B10B transmitter and receiver data paths.
• Receiver decoding.
• Electable fabric width (on transceiver level) of two, four, or eight octets per clock beat.
The 8b10b trans-coder is protocol independent, in other words, it does not include a protocol-specific
word aligner or word alignment state machine. Comma-detection is supported in this mode. The serial
data must be aligned to comma-alignment boundaries before being used as parallel data. Without proper
alignment, the incoming 8b10b data does not decode correctly. The comma character (K28.5) is usually
used for alignment purposes as its 10-bit code is guaranteed not to occur elsewhere in the encoded bit
stream.
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