Unsymmetrical delay is used to ensure that either Q or QN sets up first and then feedbacks to set the other one.Īlso refer to a similar question: Debugging Iteration Limit error in VHDL Modelsim. So, in the SRlatch.vhd, you should write Q <= S nand QN after 1 ns Time never advanceds.ġ.Make your design a sequential one (ie. This result in a infinite loop becase 100 ns + n delta time = 100 ns. For example, if you are collecting toggle data on 0->1 and 1->0 transitions, both transition counts must reach the limit. modelsimIteration limit reached at time 2 ns. All possible transition edges must reach this count for the limit to take effect. Error: (vsim-3601) Iteration limit reached at time 2 ns.module toptest bentchmoduleD flip flopmodule top wire Q. J2 or K2 | Suppose that Q changes 100 ns + 3 delta time After the limit is reached, further activity on the node will be ignored for toggle coverage. Model Technology ModelSim SE-64 vcom 6.5c Compiler 2009.08 - Loading package standard - Loading package stdlogic1164. J or K or clk changes 100 ns + 0 delta time It's equivalent process: process (J2, K2)Īlong with other processes make an infinite loop.įor example, the J-K Flip-Flop is stable 100 ns + 0 delta time In your code: f2 : SRlatch port map ( J2,K2,Q,QN ) If as a result of this computation an event occurs on a given signal, process statements that are sentitive to that signal will resume and will be executed as part of the simulation cycle. In eacy cycle, the values of all signals in the description are computed. About simulation cycle (See VHDL LRM 93 $12.6.4 and Delta Delays) Others concurrent statements are the same.Ģ. So, in your code, J0 <= not ( J and QN and clk) ) For any concurrent signal assignment statement, there is an equivalent process statement with the same meaning. In VHDL, this can happen when a signal is placed in the sensitivity list and this signal is changed in the process. What am I doing chat about anything related to programming and coding languages. Not the answer Iteration Limit Reached At Time 0 Ns what should I apparently correct, what errors are inferred from these warnings. Here in this there is a possibility of loop. Set this in modelsim.ini: Resolution 100ps Sign information on modifying the modelsim.ini file.
#Modelsim iteration limit reached simulator#
Port(J,K,clk : in bit Q : inout bit QN : inout bit) Īrchitecture structural of JKFlipFlopStruct isĪs Russell say, this error usually indicates that ModelSim is stuck in an infinite loop. Simulator :model sim Error: (vsim-3601) Iteration limit reached at time 530 ns. Port(S,R:in bit Q : inout bit QN : inout bit := '1') Can anyone guess what the problem might be? library ieee
#Modelsim iteration limit reached code#
I'm not sure what it means, but I've looked through much of my source code for errors to no success.
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I'm writing vhdl code for a jk-flip-flop on modelsim and i get an error when i try to simulate it: Error: Iteration limit reached at time 0 ns.