F-Tile Architecture and PMA and FEC Direct PHY IP User Guide
A.6.4.1. F-Tile FGT NRZ Tuning Flow
BER is the Bit Error Ratio. It is the primary figure of merit.
Eye Height value is in mV. In the attached tuning tcl script for each design example, for NRZ signaling, there is one eye height value readout. For PAM4 signaling, there are multiple eye height readouts: top eye height, middle height, and bottom eye height readouts. In PAM4 tuning, BER is sufficient and is the recommended figure of merit to choose the best TXEQ setting. The script has the PAM4 eye height measurement feature to provide an extra data point but that is optional.
FOM is an indication of the vertical eye opening as it is updated during adaptation. It is a figure of merit used when auto adaptation is ON since it relies on auto adaptation firmware. If auto adaption is OFF, FOM cannot be used. FOM is a very fast vertical eye measurement and it is not the same as vertical eye height. The larger the FOM value, the larger the eye opening. Negative FOM value implies a failure of adaptation.
Figure of Merit | Read/Write | Registers and Sequence | Description |
---|---|---|---|
BER | Read/Write | Refer to FGT Attribute Access Sequence for BER measurement | Refer to the ttk_helper_ftile.tcl (*) script for the complete implementation. |
Eye height | Read/Write | Refer to F-Tile FGT Attribute Access Sequence for Eye Height Measurement | Refer to the ttk_helper_ftile.tcl script for the complete implementation. |
Corrected symbol rate with FEC | Read Only | 0x194 0x198 |
Refer to thettk_helper_ftile.tcl script for the complete implementation. Refer to F-Tile Ethernet Intel FPGA Hard IP Register Map for more information. |