3.1. Guideline: VREF Sources and VREF Pins
3.2. Guideline: Observe Device Absolute Maximum Rating for 3.0 V Interfacing
3.3. Guideline: Voltage-Referenced and Non-Voltage Referenced I/O Standards
3.4. Guideline: Do Not Drive I/O Pins During Power Sequencing
3.5. Guideline: Stratix® 10 I/O Buffer During Power Up, Configuration, and Power Down
3.6. Guideline: Maximum DC Current Restrictions
3.7. Guideline: Use Only One Voltage for All 3 V I/O Banks
3.8. Guideline: I/O Standards Limitation for Stratix® 10 TX 400
3.9. Guideline: I/O Standards Limitation for Stratix® 10 GX 400 and SX 400
4.3.3.2. Full-Rate or Half-Rate DDIO Input Register
The input side of the full-rate and half-rate DDIO input registers are the same. You can properly constrain the system by using a virtual clock to model the off-chip transmitter to the FPGA.
Figure 35. Full-Rate or Half-Rate DDIO Input Register
Command | Command Example | Description |
---|---|---|
create_clock | create_clock -name virtual_clock -period "200 MHz" create_clock -name ddio_in_clk -period "200 MHz" ddio_in_clk |
Create clock setting for the virtual clock and the DDIO clock. |
set_input_delay | set_input_delay -clock virtual_clock 0.25 ddio_in_data set_input_delay -add_delay -clock_fall -clock virtual_clock 0.25 ddio_in_data |
Instruct the Timing Analyzer to analyze the positive clock edge and the negative clock edge of the transfer. Note the -add_delay in the second set_input_delay command. |
set_false_path | set_false_path -fall_from virtual_clock -rise_to ddio_in_clk set_false_path -rise_from virtual_clock -fall_to ddio_in_clk |
Instruct the Timing Analyzer to ignore the positive clock edge to the negative edge triggered register, and the negative clock edge to the positive edge triggered register.
Note: The ck_hr frequency must be half the ck_fr frequency. If the I/O PLL drives the clocks, you can consider using the derive_pll_clocks .sdc command.
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