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199 Threads found on Clock Constraints
Hi. Now, I'm trying to implement the DUT which has dual clock edge. always @(posedge clk or negedge clk or posedge reset_n) begin if(reset_n) begin num_counter <= 1'b0; end else begin num_counter <= num_counter + 1; end end But I don't know what am I supposed to make a SDC file if I want t
if you are using special routing rules or constraints, you can make them softer. for instance, if clock is always 2W2S, you can make it 1W2S or something. if the problem is related to a specific cell (think something like AOI22, lots of pins), you can replace it for simpler cells and run OPT followed by route again. if you have max tran, ma
Why would you want to do that? Is your i/p data signal that is connected to the clk pin toggling (even after long intervals)? Think about the properties of a flip-flop and the role of the clock pin. A clock signal is just a special data signal. I think you have to put special timing constraints on that clk i/p of the flop.
It's most likely an estimate based on the SDC constraints for the clock and a 12.5% toggle rate of all FFs that use that clock. It's therefore likely to be very inaccurate, probably in excess of +/-30% off. FPGA dynamic power analysis tools for both Altera and Xilinx do exactly this type of calculation and report that the results have very (...)
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 CPLD, i
You use constraints, if you don't use constraints then the tools will do an extremely poor job of meeting any timing (as there isn't any requirements). I guarantee it will be very slow compared to using constraints, unless the design is so simple that it always implements the same way regardless of the clock constraint or (...)
Hey experts, I have a question related to Multi cycle paths. I know that by default, the hold is always checked one clock edge prior to setup edge. Also during MCO exceptions, we add hold constraints where we move hold checking to different edges. Can anyone explain: 1. why hold checks are done 1 clock edge prior to setup edge.? (...)
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?
If you have issues routing the chipscope, you can always add a serial to parallel converter on the high rate signals. eg, have multiple registered versions of the signals that then go to slower clocked register that go to chipscope. The results are harder to analyze. Some trigger conditions might not be possible (i forget what the limit is for a
Hi all, I have a doubt related to clock uncertainty in the FPGA design flow using (for example) Quartus. Why should someone want to overwrite the clock uncertainty generated by "derive_clock_uncertainty" using the "set_clock_uncertainty"? Isn't the derived uncertainty enough precise to be trusted by the designer? (...)
Hello, I wrote a code for DFlipFlop in VHDL to be used in a TOP module. I want to put the placement constraints (LOC or RLOC) in VHDL code in order to put the FlipFlop in a specifc SLICE. Here is the DFlipFlop code: entity DFF_1 is Port ( D : in STD_LOGIC; Q : out STD_LOGIC; CLK : in STD_LOGIC; --clock RESET : in S
Hello, I am having an issue in combining two clocks signals in one project. I am using DE2 Altera board. I am also using Nios processor. So, basically I am trying to merge to independently working projects into one and build my thing on it. I have one clock signal 50MHz for one project and I have another 27MHz signal for another project. I port
Cost can be measured in clock cycles for buffered texture memory to prevent overflow or cost of STA analysis which can be hours or days depending on constraints with iteration on cell parameters for a complex design. (e.g. ARM)
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 fi
Dear all, Thanks in advance for your help! I have synthesized my design in synopsys design vision, at first I create the clock to 10 ns, and the timing report showed that slack is 0, and the critical path is one bigger multiplier. Then I changed the clock to 4ns, this time it took me more time to synthesize my design(2
Considering maximum AD5542 clock frequency of 25 MHz, the pratical answer is: you usually get away without any IO constraints. If no large external delays are involves, e.g. slow drivers or opto isolators, you can rely on the standard SPI timing design, send data on one edge of the serial clock, latch it on the other edge. This gives (...)
I have also a question regarding timing the unconstrained input and outputs on xilinx implementation I got a clock of 3ns without having to specify any constraints but altera requires them specified I have checked the timequest tutorial but did not understand on what to base my input and output timing constraints in additio
I would suggest to have the following constraint first. 1. clock period 2. input delay 3. output delay 4. clock uncertainity 5. clock latency 6. set load 7. set input transition 8. False Path / Multi-Cycle Path ( between the clock domains if any ).
Hi all, I have a design like below, Let us say, the design contains CLK1, CLK2 - input clocks D - data input Q - data output SEL - mux selection if the design contains two sub modules say U1 and U2, for easier under standing I am instantiating the instance like below DUT U1 (.D(D), .CLK(CLK1), .Q(Q1)); DUT U2 (.D(D), .CLK(CLK2), .Q(Q2)
It seems they really want to motivate you to learn how to design with PIC with 1973 design constraints. I would create a master clock to derive all the output results being the lowest common multiple of all resolution , frequency and time constraints. 1. Measure period between pulses, T counting master clock pulses, fc (...)

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