Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 4/01/2024
Public
Document Table of Contents

5.5.6.6.1. Generation of Dynamic Termination Signal

During read operations, the control of the dynamic termination signal (TSEL) for the data DQ and DQS is performed as follows:
  • For the DQ pin: Uses the data_select_tsel_start and data_select_tsel_end fields in the phy_dqs_timing_reg register
  • For the DQS pin: Uses the dqs_select_tsel_start and dqs_select_tsel_end fields in the phy_dqs_timing_reg register
A lower value implies that the rising or falling edge of the TSEL signal occurs earlier while a higher value implies that the rising or falling edge occurs later. The TSEL signal is ON for a minimum of 2 clock cycles after the negative edge of the rebar_dfi signal or negative edge of the dfi_rd_pre_post_amble signal. The start time can be delayed by the *tsel_start fields. The TSEL is OFF for a minimum of 1 clock cycle after the internal DQS gate signal goes low. The end time can be delayed by the *tsel_end fields. Each step has a resolution of ½ clk_phy clock cycle. The termination value for DQS and DQ pins when the TSEL signal is set or clear is controlled by the phy_tsel_reg register.
Figure 165. Generation of Dynamic Termination Signal (TSEL)