Altera ALTDQ_DQS2 - Manual (Page 88)

Figure 59: Side Read Operation Waveform
Side Write Operation
The side write operation begins between 9.185 µs and 9.255 µs. The data written out from the DQS driver
is also stored in
checkfifo
.
The following figure shows the waveform for the side write operation.
Figure 60: Side Write Operation Waveform
Note: The incoming data at
dq
is edge-aligned to the
strobe_io
.
DQS Read Operation
Data validation is done by comparing data received by the ALTDQ_DQS2 core (
read_data_out
) against
the content of the
checkfifo
.
DQS read is initiated by the DQS driver when
dqs_read
is asserted at 9.345 us. The
lfifo_rdata_en_full
(
dqs_read
) of the ALTDQ_DQS2 IP core is also asserted for the entire length of
the desired read burst, which in this case is 12 full-rate cycles. As the DQS agent receive the read
command, it is then ready to sends out data as per requested. This is shown with
agent_output_enable
being asserted from 9.380 us to 9.445 us. During this period, the DQS agent drives the strobe and data
lines of the external memory interface. In this test bench,
strobe_io
is driven by
dqs_agent_to_ios
.
When output enable is deasserted,
strobe_io
will be set to Hi-Z.
88 Side Write Operation
UG-01089
2014.12.17
Altera Corporation ALTDQ_DQS2 IP Core User Guide
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