ALTDQ_DQS2 IP Core User Guide

ID 683742
Date 5/08/2017
Document Table of Contents

DQS Write Operation

The driver asserting the dqs_enable signal at 18.803 ms begins the write operation. The dqs_write signal is asserted at 18.811 ms. The write_oe_in signal of the ALTDQ_DQS2 IP core is set to high and is ready to send data to the DQS agent. Data are written to the dqs_writedata of the DQS driver and then reflected in the dq signal of the ALTDQ_DQS2 IP core. The data written out from the DQS driver are stored in check_fifo. The dqs_write signal deasserts at 18.851 ms. The dqs_enable deasserts at 18.859 ms. Outgoing data from the ALTDQ_DQS2 (dq) is center aligned to the write clock (dqs_ios_to_agent).

The following figure shows the DQS write operation waveform.

DQS Write Operation Waveform

Note: Before and after the DQS write operation, the dq signal is in Hi-Z mode to filter any unwanted glitch on the bidirectional port.

The following figure shows the waveform after executing the file. The write_oe_in signal is held high throughout the five sets of valid write_data_in between 18.811 ms and 18.851 ms. Centre aligned output data appears on read_write_data_io between 18.822 ms and 18.86 2 ms. The output_strobe_out is a free running clock while the read_write_data_io is driven at Hi-Z when there is no data transaction.

DQS Write Operation Waveform After Executing the File