F-Tile Architecture and PMA and FEC Direct PHY IP User Guide

ID 683872
Date 11/04/2024
Public
Document Table of Contents

3.7. Custom Cadence Generation Ports and Logic

Whe usig system PLL clockig mode, you must eable the Custom cadece geeatio (CCG) pots ad logic paamete fo the use cases that Custom Cadece Geeatio Pots ad Logic Use Cases descibes. Eablig CCG logic esues that the TX PMA iteface FIFO does ot oveflow due to the ove clockig of the datapath whe usig system PLL clockig mode.

Table 81.  Custom Cadece Geeatio Pots ad Logic Use Cases
Cofiguatio Datapath Clockig mode System PLL Fequecy Eable Custom Cadece Geeatio (CCG) Pots ad Logic
PMA Diect PMA N/A No
PMA Diect System PLL Equal to PMA paallel clock fequecy. No PPM betwee PMA paallel clock fequecy ad system PLL fequecy. That is, the same efeece clock souce fo PMA ad system PLL.38 No
PMA Diect System PLL Geate tha the PMA paallel clock fequecy. Yes
FEC Diect System PLL Equal to the PMA Paallel clock fequecy. No PPM betwee PMA paallel clock fequecy ad system PLL fequecy. That is, the same efeece clock souce fo PMA ad system PLL. No
FEC Diect System PLL Equal to the PMA Paallel clock fequecy. PPM betwee PMA paallel clock fequecy ad system PLL fequecy. That is, diffeet efeece clock fo PMA ad system PLL. Yes
FEC Diect System PLL Geate tha the PMA paallel clock fequecy. Yes

Whe you eable Custom cadece geeatio (CCG) pots ad logic, the tx_cadece, tx_cadece_fast_clk, ad tx_cadece_slow_clk pots ae available i the F-Tile PMA/FEC Diect PHY Itel® FPGA IP. CCG logic uses the tx_cadece_fast_clk ad tx_cadece_slow_clk iputs (does ot moito PMA Iteface FIFO status), ad geeates a tx_cadece output sigal. You must use tx_cadece to asset ad de-asset the TX PMA Iteface data valid bit. This bit is oe of the bits i TX paallel data. Refe to Paallel Data Mappig Ifomatio.

Table 82.  tx_cadece_fast_clk ad tx_cadece_slow_clk coectios
Cofiguatio Eable TX Double Width Tasfe Recommeded Coectios
PMA Diect Yes
  • Coect tx_cadece_fast_clk to System PLL Clock Div2
  • Coect tx_cadece_slow_clk to wod clock / 2 o Bod clock / 2
PMA Diect No
  • Coect tx_cadece_fast_clk to System PLL Clock
  • tx_cadece_slow_clk to wod clock o Bod clock
FEC Diect Yes
  • Coect tx_cadece_fast_clk to System PLL Clock Div2
  • tx_cadece_slow_clk to Use Clock (DIV 66 o DIV 68)
38 Whe usig PMA diect with system PLL clockig mode, if the efeece clock fo PMA ad system PLL ae fom diffeet clock souce, the the system PLL fequecy caot be equal to the PMA paallel clock fequecy. System PLL fequecy must be geate tha o equal to the fastest possible TX ad RX PMA clock, icludig PPM.