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I have finished synthesizing my circuit in design compiler. Now I want to do a gate level simulation in Modelsim in order to get the power consumption. The gate level simulation works correctly, but generates "xxx" when annotated with the SDF generated by design compiler. I've tried to reduce the clock frequency but still get the same result. I sho
I am not sure which constraints you are referring to. It depends on which constraints you added/modified. If more pessimistic constraints were used during synthesis and if they were relaxed in Tempus, the results are bounded. If more optimistic constraints were used during synthesis, then (...)
Hello, I ran synthesis on a IP many times with a variation in the frequency each time. and no additional constraints given during synthesis to the design. please look into the attachment , i observed a consistent zero slack from 500 Mhz to 1 Ghz. Is everything ok or iam missing anything ? give some suggestions
syntax errors will throw an error in the synthesis tool incorrect net names will throw warnings about nets not existing. As for the timing, thats something you need to specify.
Hi All, I am using Virtex 7 1157 FPGA. My design with RTL is freezes. I cannot modify a single line in the RTL. I needs to infer the DSP blocks for particular adder logic in my design. During the Synplify synthesis, I observed that automatically these adder are not using DSP blocks. Is there any *.sdc constraints for inferring the DSP block
The ASIC synthesis tools like Cadence RTL Compiler will report static and dynamic power consumed in your design in the power reports. How does the tool calculate the dynamic power even without the switching information??
FPGA synthesis tools have timing analysis to check if a design is able to run at the intended clock frequency and usually also implement timing driven synthesis to tune the design for maximum speed if required. So the first step would be to write suitable timing constraints and determine the achievable counter speed. Not knowing the used (...)
Hello, i want to do a power analysis on the post-synthesis netlist of my design. My main design inputs are connected with one of my sub-designs inputs(i.e. with the component's A inputs). My main design outputs are connected with one of my sub-designs outputs(i.e. with the component's B inputs). Here is the problem: When i set constra
The software "Vivado" has support for multithreading with 4 CPU threads and some of the steps only have support for 2 CPU threads. So no you can't magically make Vivado use 8 CPUs. To make it run faster, use partitioning and lock partitions that won't change, check that you didn't over constrain the design or have too many constraints that overl
Hi. As I know, basically, we do synthesis in worst case(Max delay data path, Min delay clock path). But I want to know that what if I use clock gating then what constraints are needed to my sdc? What kinds of aspects are needed to consider to synthesis within clock gating ? Is this only functionality problem?
Suppose I have constraints for five blocks for the synthesis of each of the five blocks. Now this five blocks are instantiated at a top level module and I want to synthesize this top level module. How should we proceed? How can we port the constraints of these five blocks at the top?
Hi, I have the logic that generate DDR output signal e.g. assign DDR_out = clk ? DDR_pos_reg : DDR_neg_reg and using DC to synthesis it. clk signal is the select of the mux and create data value on both edge. This architecture is valid as mentioned in thread. But I checked the clock tree log fil
What should I do if I find out the area after synthesis is larger than I expected? (this is a question that I encountered during an interview, can any one help me find the answer? Thank you )
Well the synthesis used an input file SDC hand written where the designer indicate the constraints, it is not mandatory, as RTL compiler for example has his own command to constraint the design. using SDC is recommended and could be used by the majority of the synthesis tool. Personally, I used as input of the place& route tool the generated (...)
What are the minimum required constraints to be given while synthesising a design? 1. clock period 2. input delay 3. output delay 4. clock uncertainity 5. clock latency 6. set load Other than the constraints listed above, what are the basic constraints required?
How to check the SDC is correct or not at RTL syntheis level?
Im working on a Warning Speedometer project, im currently having trouble thinking about circuit topologies that can be used for frequency multiplication. Once you do the math (refer to the guidelines below) you see that in order to go from frequency to mph you multiply the frequency of interest by 2.88,this is why i want to design a frequency multi
Hi All, What Optimization constraints do exist? 1) defining cost groups 2) what next? Thank you!
Without constraints that directs the synthesis tool to keep redundant logic cells, or using low level primitives to describe the circuit, you won't get a working ring oscillator. I could tell you how to do it in Altera Quartus, I'm not using Xilinx. But I'm quite sure that it's possible with Xilinx tools, most likely you'll find respective hints
Hi All, What should I check after logic synthesis? As for me, here is the list: 1) Timing Warnings (negative slacks) 2) Gate Count What am I missing? Thank you!
Hi guys, I'm wondering whether or not to constrain the clock skew (uncertainty) for placement and clock tree synthesis. Does this affect the clock path during optimization process when building clock tree, e.g. buffers are added to clock path to satisfy the constrained skew. Or it's just optimization on data path to satisfy setup/hold require
Without floorplan, it is not relevant to fix DRV (trans/cap) during the synthesis step. This must be done during the PnR.
If you are interested for LEC, you just have to provide the constraints. If your device is not stitched and only scan replaced, no need to do LEC as there is not any DFT connection. When you do synthesis using Synopsys DC Compiler, .svf file is generated for particular synthesis, we just need to provide .svf file to the Synopsys formality (...)
U can use the synthesis constraints itself as the base. Just source this constraints file during the primetime run...
Xilinx reports a maximum freqency for the design when synthesis is done without using ucf or xcf. How reliable is the freqency reported? And does the tool check all timing paths and then report a maximum freqency? That is the timing that you have given the lack of constraints, so yes it has been fully analyzed.
FULL CHip FPGA netlist?What is this supposed to mean? FPGA netlists are either EDIF or RTL like any other netlist. If you mean the proprietary (i.e. the secret format) vendor post map, post place and route netlist, then definitely there is no way to do any kind of formal verification. Nobod
STA can be run on 2 occasions : pre-layout & post-layout. Pre-layout STA requires the post synthesis netlist & constraints. Post-layout requires the P&R netlist, the constraints & the SPEF file generated from a tool like STAR RC. If you have a "gate level netlist form synthesis", then you must be doing pre-layout STA. You (...)
Let's say i have a verilog design the size of a small SoC. It is largely correct, and works nicely in an FPGA on one board. On another identical board, however, it starts giving out intermittent errors, i.e. the I2C gets garbage sent out every 10 bytes. But if i do some irrelevant change, like change HW version register value, to force a re-sy
This is a synthesis script. It does not make any sense running gate simulation with a post synthesis netlist with a SDF. You should not use an SDF in this setup. SDF is only used with a post layout netlist.
It the responsibility of the designer to communicate it to the synthesis engineer if there are any multicycle paths in the design. The designer is the only person familiar with the design. The synthesis engineer is unaware of the design details. Once the synthesis engineer is aware of multicycle paths, he can form the necessary (...)
Try creating logic lock regions inside the other region and exclude logic from being placed there. Perhaps a couple of columns and rows. That will force the placer to not pack everything as close to each other. Regards - - - Updated - - - You might also consider playing around with the synthesis settings.
M not getting the error with ur code, btw, which synthesis tool are you using ?
HI all, Can anyone let me know timing related questions which can be asked during synthesis process ? or any other timing concepts or timing related questions which can be asked during interview. Thanks Limitless_21
If we do not define clock, than what happened? synthesis failed means shows the error/message or it just create the RTL to Gate Level netlist? -> RTL -> Gates conversion doesn't need clock definition. -> you can use any other constraints to define the timing for your design(like max delays etc). -> Clock const
Hello, everyone~ In my digital design, there are two modes for configuring operation clock frequency. CPU:300MHz, Bus:150MHz (2:1 mode) CPU:180MHz, Bus:180MHz (1:1 mode) As you see, the worst case of CPU is 300MHz, and the worst case of Bus is 180MHz. But, I can not give clock period of 300MH
There are many aspects to cause the size different, both tools are running with different optimization method, this is normal to have size different but not more than 20% different btw both. I only can guess the constraints in both could be different, e.g in synthesis you have use WLM, (top, enclosure, segmented) but i synthesis the RC are (...)
98085 Can some one help me to define SDC constraints on the output of the MUX (at the extreme end.) If i give : clock_generated_clock -source CLK -divide_by 1 then the sequential path is left out but if i give : clock_generated_clock -source CLK -divide_by 2 then the combo path
Could you post the constraints in the UCF files as well as the Timing errors that you are getting. It would be good if you could also tell us what synthesis and PNR options you are using the ISE Tool.
Hi all, 1) Could you please let me know how can I consider timing-related constraints on place and route. In DC when we are performing synthesis, we can put a kind of constraint on the maximum delay between inputs and ouputs (e.g. delay between in1 and out1 not exceed X ps). I am wondering if there is a similar method in encouter? 2) I for
You want to avoid to redo the synthesis? So you could add the constraint in the PnR tool.
Hi friends, I synthesize a very simple veirlog code but I got an following error when I did "synthesize -to_mapped". There is nothing between the single quotes. How can I find what and where the error is? I will list my code and tcl file. BTW, I used RTL Compiler. Thanks. Error : A required object parameter could not be found. [ge
Did you check Characterization in DC?. The allocated budgets can be used to drive the synthesis of individual blocks. The budget generation and allocation process is iterative. You use the RTL budgeting flow to allocate initial budgets, then use the initial budgets to synthesize lowerlevel blocks. You can apply the synthesis results to the bud
Hello all, I am using RTL compiler to synthesize a pure combiniational digital designs. I would like to know how to constraints the synthesis tool to minimize the Area as its first periority or even may be the only periority. The shell script I use to synthesis my designs is: #/bin/sh SYN_ID=$2 FILE=$1 SYN_TOOL=rc (...)
THIS IS FINAL synthesis REPORT OF MY DESIGN. iT HAS"a" AS ITS INPUT,but it's taking a as clock,Dont knw WHY.PLS HELP. SECONDLY,if the same design(which took input as clock,on its own) without clock gives, timing report as Minimum period as well as Maximum combinational path delay,IS THE REPORT CORRECT?? Clock Information: --------------
Q) how inputs of the combo logic cone for a same compare point can differ between golden and revised A) Depends on what options is used in synthesis to get netlist and constraints you have applied like DFT. Q) What is the probable logic transformation which can be happen for the same compare point between golden and revised w.r.t mapped and not-ma
Yes it could. For example, some flip unlocked, which will be removed by synthesis.
Logic optimization, a part of logic synthesis, is the process of finding an equivalent representation of the specified logic circuit under one or more specified constraints. Generally the circuit is constrained to minimum chip area meeting a pre-specified delay.
Just want to know the opinion of the forum. Is it preferred to use exactly the same set of constraints for both synthesis using DC, and STA using PrimeTime? Does the synthesis tool use the false path specifications, or max transition constraints? Or can we use a simpler constraint file to do synthesis, (...)
Hello Can we apply XDC "Xilinx design constraints" file -which is nearly similar to SDC "Synopsys Design constraints" in syntax and commands- to XST "Xilinx synthesis Tool" in ISE, instead of applying the XCF "Xilinx constraints File" or the UCF files ? In case the answer is no, So When can we use XDC files with ISE ? (...)
1- synthesis should be done with the worst corner(s) to reach the setup constraints. 2- place & route, I usefully have in MMMC flow, how many setup condition, where I want to be sure my design must reach the setup constraints, and for the hold condition, all corners I want to have my design to be functional. I mean, some corners do not have (...)