Questions tagged [constraints]
The constraints tag has no summary.
58 questions
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Why am I getting this warning in Vivado?
After the Run Linter is finished, I clicked on the Schematic button and got this warning.
The Elaboration page of the Project Settings:
Why would loading I/O planning constraints slow down
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How to specify clock period in Synopsys Design Constraints file (SDC)?
The SDC file:
create_clock –period 37 –waveform {0 18.519} {clk}
While reading SDC file in the Quartus, I get following error:
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Found illegal assignment group name conflicts with top-level node name
How to fix the follow errors was appeared after pin assingment (in Pin Planner window) and project compilation:
"Error: Found illegal assignment group name "key" -- conflicts with top-...
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699
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Correct SPI interface timing constraints
I'm struggling setting up timing constraints for an ADC SPI interface.
The design is a simple ADC Master interface working at 25 Mhz, same frequency of the system.
First of all I gated the output SCLK ...
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203
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How to use FPGA system clock for my design in vivado?
Problem is my device don't use system clock generator (what me need) for synchronization,but use clock signal is generated by TestBench what connected via external I/O ports of FPGA.
I have ...
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327
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FPGA DDR timing constraints
I have EMMC master for FPGA. Please tell me how to write constraints on ports in DDR mode? I tried to write constraints but I doubt the correctness
Specification:
JEDEC Standard No. 84-B51
P.S. Here ...
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2
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260
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Altium: Is it okay to waive this constraint violation between two elements of the same electrical component?
All of my electrical components are listed as having such clearance constraint violations when I open the PCB Rules and Violations window. I have tried lowering the minimum clearance from 0.254 mm to ...
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FPGA output timing explained
As a hardware designer you have consider the timing constraints of both the input and output device. Input devices specify a setup and hold time reference to the clock (the time in which the data ...
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Timing parameters of sequential circuit - digital electronic
Problem
Determine the timing parameters (\$T_\text{cQ,bb}, T_\text{su,bb}, T_\text{h,bb}\$) for the black box logic circuit seen below: -
Attempt
\$T_\text{cQ,bb}\$ is the time it takes for the ...
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129
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Best practice to constrain dynamically tuned FPGA->DAC data path
Data is moved from the Zynq 7010 to AD9779A DAC using parallel SDR link at 155.52MHz. This DAC generates DATACLK clock that is used to clock data out of the FPGA (see picture for the relevant FPGA ...
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How can I declare individual PMOD pins as input or output in an FPGA?
I have a Xilinx Basys 3 demo' board, which contains the Xilinx Artix-7 XC7A35T-1CPG236C FPGA.
I want to use the board's PMOD header as an SPI master interface. Most of the pins are outputs, but MISO ...
- 1,463
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How to constrain a source-synchronous FPGA input?
I have a source-synchronous input to my FPGA (an Intel Cyclone 10 GX 10CX085), coming from an external chip whose datasheet gives the following information:
fmax = 300 MHz (single data rate)
tsetup = ...
- 309
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332
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Use SDC format for timing constraints on Xilinx CPLDs
Due to the chip shortage, I'm trying to perform timing analysis of an existing CPLD design for a number of alternative chips from different manufacturers.
I have existing hardware description source ...
- 3,144
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SDC constraint inside Xilinx ISE
Inside ISE timing constraint editor window, which following sub-section shall I use set_clock_group to solve the STA setup timing violation path #1 due to cross-clock signal ?
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How to correctly constrain a clock network with lots of mux branches?
Let me simplify a common clock network structure used in my company:
Firstly, there're multiple true clock sources (PLLs, external input, or RC OSCs).
Right at the beginning when these sources are &...
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Unable to constrain HPS peripheral pins on intel agilex fpga dev kit
I'm having trouble getting the Hard Processor System (HPS, the embedded hard processor of the agilex fpga series) to work properly on the Intel Agilex Dev kit version 3. The issue says that that there ...
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717
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SystemVerilog randomization for a fixed sequence of values
I need to randomize addr such that addr is 'h0 three times followed by addr as 'hf for two times. The values of addr should be in the sequence even if it is used with randomization. I tried using a <...
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What is the setup/hold time of the RMII receive interface of the TI DP83630 phy chip?
I'm interfacing the TI DP83630 phy chip to FPGA over RMII interface and need to write the timing constraints. I'm having difficulties interpreting the receive interface setup and hold time from the ...
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SDC (Synopsys Design Constraints) Timing Exception for Latch Before Launch - FPGA
I am acquiring data from an ADC whose serial output makes the first bit available immediately after completion of a conversion. Then, the FPGA sends clock-pulses to the ADC to shift-out the remaining ...
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FPGA Timing Constraints
I am fairly new to FPGA design and I am working on a project where the FPGA is the SPI Slave.
Are there supposed to be constraints on the Master Clock input signal/ MOSI / Chip select?
What is the ...
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Passing input on one pin of FPGA straight out to another output pin for monitoring
I need to monitor a signal as it is going into the FPGA, tracking down a potential noisy input or slow rising signal issue. I want to use an external oscilloscope to see what the FPGA sees (as ...
- 661
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Clock constraints for SDC file
I found several related answers to my question but none of them seem to clarify my case. I followed this answer and this one, but still getting warnings and when synth/impl. Here's the conceptual ...
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Intel FPGA: applying timing constraints
I have a data signal, select and clock signal which I am sending from the FPGA to another chip and I need to constrain them so I don't violate setup/hold time etc.
I have tried to write and SDC file, ...
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Constrain plane clearance from annular ring in Altium
I need to constrain a plane from shorting to the annular rings of a number of vias.
The dialog found at ...
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862
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How to estimate timing contraints for FPGAs?
I try to find out how to specify the timings restrictions in FPGA designs correctly (in .sdc/.xdc files). I know what setup and hold times mean. However: How do I find out, what timing constraints my ...
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SDC constraints for source clock and derived clock
There are two clocks in the system, clk2 is derived from clk1 with a 180-degree phase shift. There is 1-bit data from clk1 to clk2.
I know this is a kind of asynchronous scenario and the traditional ...
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Vivado : constraints setup for SPI interface with common clock
I have been using Vivado 2018 for a system level design and am having trouble with a SPI interface programming. A block diagram of my system is shown below.
The Artix-7 FPGA (on the motherboard) sends ...
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2
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3k
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Altium Unrouted Net in Fill
I am trying to use vias on a fill to connect copper in Altium, but I keep getting unrouted net constraint errors. I have the following:
The red square and blue rectangle (which extends fully ...
- 1,063
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2
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580
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FPGA automatic pipelining?
I have a synchronous datapath in my design that fails negative slack timing check, and I could most likely fix it by putting extra pipeline registers between datapath blocks by changing RTL sources.
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Writing SDC constraints for asynchronous clocks
I am new to SDC constraints, in synchronous clock definition say A and B are synchronous with each other, then we can define create_clock on A port (input) and <...
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Is it possible to integrate all passive components? [closed]
Looking at a Circuit Board from a recent consumer product, I still see many discrete components (diodes, resistors, capacitors, amplifiers), which occupy space and have to be soldered into the board.
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427
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LTSpice constraints on plots
A have a circuit for which I have parameterized some of its resistors with the .STEP command. Consequently, I have many different graphs when I simulate the circuit. I would like to know if it was ...
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99
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Lower Power Inductive Heating Circuit Design Questions
I'm trying to design a very low power (<=10W) inductive heating circuit that will heat the work material to 40-50degC. I've seen plenty of Royer Oscillator circuits online (see here: http://www....
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How to get a default UCF file of Xilinx Virtex-5 XC5VLX110?
How to get a default UCF file of the Xilinx Virtex-5 XC5VLX110?
It doesn't seem to be anyhere. If I have to make it by myself, would you let me know how to ...
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How to specify a minimum clock to output time in output timing constrain?
In design, an external clock pin triggers a flip-flop, where the output goes to an external data pin.
Using Xilinx ISE, how can I specify a timing constraint, so the output should be held for some ...
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SDC constraints for two flop sychronizer
I have doubt, What should be proper SDC constraint for CDC module, i.e., two flop synchronizer.
between "dat driving by aclk to <...
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Timing constraints for DDR output multiplexer
Consider the following circuit, which multiplexes the d0 and d1 inputs to the y output in ...
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How to specify timing constraint for two paths to have a equal delay in Vivado
I am trying to sample an asynchronous signal in multiple clock-domains. I do not care too much about the absolute delay from the source of the async signal to the sampling FF's, but I want to ...
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275
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Constraint relative arrival time for a group of signals
Imagine a situation where the absolut delay of a group of signals doesn't matter, but it must be ensured each signal of the group has roughly the same delay until it reaches a certain point, say a FF. ...
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768
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Multicycle : Is it possible?
I've to constraints an Lattice Semiconductor FPGA and I've some doubts about the multicycle constraint described here. I've the following RTL :
Basically it is a counter that is driven by a rising ...
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1k
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Setup and hold time violation constraints for Xilinx Fifo generator
I have a problem concerning the Xilinx Fifo generator and timing contraints described in the fifo manual.
I am using the fifo generator version 9.2 (manual ) to generate a fifo.
I would like to ...
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BlockRAM location constraints (Xilinx)
I have a VHDL module in which several block RAMs are inferred. Now I would like to place these block RAMs into a certain region of my FPGA (close to some IO pins).
How do I do this using Xilinx ...
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Understanding timing constraints
I don't want an introductory text on timing constraints, nor an application note, an user manual, a webinar. I read them all, already, many times. The concept behind timing constraints is very easy. ...
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Setup and hold time
Of the setup and hold timing constraints which are to be met to get a stable output, which one is critical in estimating the maximum clock frequency of a circuit?
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Clock domain crossing timing constraints for Altera
I have a slight problem with my clock domain crossing timing constraints.
I have two clock groups
set_clock_groups -asynchronous -group {clk_A} -group {clk_B}
...
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How do you constrain input delay for a multidimenionsal input vector?
I am defining SDC input constraints for synthesis of a small module that is part of a larger ASIC design. I plan to run the module through synthesis using Synopsys tools. A few of the inputs to this ...
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751
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Rise/fall time constrains for ADC?
Does the sampling clock rise/fall times for ADCs matter, or they can be virtually 0 seconds? Can they be slow? In particular, I could not find anything about rise/fall time constrains for AD9235.
...
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What is the use of OFFSET IN/OUT constraint for FPGA design when using register in IOB?
The following is asked in the context of Xilinx FPGAs (my experience), but may also apply to similar technologies offered by other vendors.
Background: When writing constraints for FPGA I/O, there ...
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ASIC timing constraints via SDC: How to correctly specify a multiplexed clock?
Introduction
Having found multiple, sometimes conflicting or incomplete information on the internet and in some training classes about how to create timing constraints in SDC format correctly, I'd ...
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ASIC timing constraints via SDC: How to correctly specify a ripple-divided clock?
Introduction
Having found multiple, sometimes conflicting or incomplete information on the internet and in some training classes about how to create timing constraints in SDC format correctly, I'd ...
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