Altera ALTDQ_DQS2 - Manual (Page 86)

Dynamic Configuration
At 100 ns, there is a high pulse on the
beginscan
signal. When the
agent_output_enable
signal is pulled
low, the
strobe_io
and
agent_dqs_in
goes to Hi-Z between 110 ns and 8.795 us time mark, some
internal calibration is being carried out. Dynamic configuration is the main feature used. At 8.795 us time
mark, the
enable_driver
signal is asserted. This specifies that the internal calibration is completed, and
the control is passed on to the host controller (the DQS driver) to perform the normal read/write
operation.
Note: For RTL related to dynamic configuration operations in this design example, refer to
config_controller.sv file.
You can override the static values at runtime with a scan chain using the dynamic configuration feature in
the ALTDQ_DQS2 IP core. To help you achieve static timing closure, the dynamic configuration feature
allows you to override the static values at runtime with a scan chain. Each I/O and the DQS logic contain
its own scan chain block (shift registers). This section shows you how to serially scan configuration bits
into each scan chain block, between 100 ns and 8.795 us time mark.
The following figure shows the waveform for the dynamic configuration simulation generated after
executing topwave.do (located in the simulation/modelsim folder), between the high pulses of
beginscan
and
scandone
.
Figure 56: Dynamic Configuration Waveform
Because the
enable_driver
signal is asserted at 8.795 us time mark, following read and write operations
will be executed by DQS driver.
Note: The
driver_clk
is running at the same rate as the core
Related Information
• Dynamic Reconfiguration for ALTDQ_DQS2 on page 38
DQS Write Operation
The driver asserting the
dqs_enable
signal at 8.925 µs begins the write operation. This will configure the
ALTDQ_DQS2’s
output_strobe_ena
to high, getting ready to send out strobe to the DQS agent. The
dqs_write
signal is asserted at 8.935 µs. This sets the
write_oe_in
signal of the ALTDQ_DQS2 IP core to
high, getting ready to send out data to the DQS agent. The 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 is also stored in
checkfifo
. During the DQS write operation, the
strobe_io
and
agent_dqs_in
is toggling.
Dqs_write
deasserts at 8.985 us and
dqs_enable
deasserts at 8.995 us.
Outgoing data from the dq signal of the ALTDQ_DQS2 IP core is center-aligned to the strobe
(
strobe_io
).
86 Dynamic Configuration
UG-01089
2014.12.17
Altera Corporation ALTDQ_DQS2 IP Core User Guide
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