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55 Threads found on Asynchronous Synthesis
It is because you missed a load of variables from the sensitivity list of your always block, because it is asynchronous logic. You should be using always(*) for the block, as it will be updated also on adr_i, cache, ex_missed_dat_i. I highly suggest though that you add a clocjk to the system and make the design synchronous.
---------------------------------------------------------------------------------- -- Company: -- Engineer: -- -- Create Date: 21:21:54 11/13/2016 -- Design Name: -- Module Name: t - Behavioral -- Project Name: -- Target Devices: -- Tool versions: -- Description: -- -- Dependencies: -- -- Revision: -- Revisi
As a concept, it is odd to intentionally create an async reset that is actually a sync reset. The Verilog always construct describes an asynchronous reset. You might say that it's odd in some way that an asynchronous input is described by a negedge event. The synthesis template for a edge triggered register with asynchronous
The former case does not use a reset while the latter case uses an asynchronous reset.
First glaringly obvious problem are these lines: IF (reset = '0') THEN IF(CLK'EVENT AND CLK = '1') and car_detec = 1 THEN This isn't a synthesis template for an inferred register in VHDL. The synthesis template looks like this: -- asynchronous reset rising edge triggered flip-flop dff: PROCESS (CLK, RESET) BEGIN IF R
Only use it when I am doing asynchronous logic for fun and profit.
Are you using asynchronous resets? See Xilinx WP231.
Post the code - missmatches are usually down to poor coding practice - ie. asynchronous logic.
I imagine the synthesis too indicate which latch made the issue, after that you need to read the RTL code to know what king of latch could implement the code, asynchronous set/reset, and if this kind of cell exist inside your liberty file.
in clock domain crossing, you set false path for hold while doing synthesis because two clocks are asynchronous and timing cannot checked. But you set set_max_delay and set_min_delay on these paths. so that data should reach after specified delay.
Your design doesn't follow the required scheme for synchronous logic synthesis: if <asynchronous condition> then -- elsif then -- e.g. rising_edge(clk) -- end if; The synchronous action must be mutual exclusive to all asynchronous actions manipulating a signal. There are additional problems with
state 2 => do other operations (but sub must remain the value set before) That's what we call a latch, if done in asynchronous sequential code. So apparently latch synthesis is wanted. A latch can however bring up a problem of not keeping the "value set before" correctly when the state changes. Thus you'll possibly want a
Hi, There are so many of them :) I am attaching one report - =========================================== Contents of Report Introduction 3D ACK ATACS (Automated Timed asynchronous Circuit synthesis Balsa Butler CADP CASCADE CCS-based specification Clp ConfRes DESI (DEcomposer SIgnal Transition Graph) di2pn FIREMAPS/Process
I am studying uses of synchronous and asynchronous Reset and have failed to understand some point. I will really appreciate if you can help me with it. 1) how synchronous reset synthesize to smalled flip flop? 2) logic synthesis may not identify synchronous reset and create timing issue at later stage, how? 3) asynchronous reset data (...)
I see it this way: The synthesis tool doesn't need to rewrite the code. POR is a hardwired feature that sets all registers unconditionally to zero on power-on. An asynchronous reset input of each register can optionally perform the same during operation. The result is however the same. More important than guessing about internal wiring details o
Increase the clock period to remove set up time violations. Check for multicycle paths and false paths. Filter both of these. I am not sure about asynchronous signals. Just try nominal case for STA first
asynchronous latches are mostly implemented as "logic loop", feeding back a combinational LE's output to an input of either the same LE or a different one. synthesis tools are often warning about latch synthesis, but they are obviously required in some cases, e.g. as address latches for an asynchronous multiplexed data bus. (...)
To check if reset release, initialization sequence and boot-up is proper. Since Scan insertions occur during and after synthesis, they are not checked by simulations. STA does not analyze asynchronous interfaces. Unwarranted usage of wild cards in static timing constraints set false and multi cycle paths where they dont belong. This can
There is a very good chance that the verilog won't be synthesizable (will ignore delays). You shouldn't give room for speculations. It's pretty clear that timed wait for doesn't work in synthesis, even if the code compiles without errors. .asynchronous timing circuits, e.g. involving logic cell delays can be designed in FPGA, but ar
Clock nets and asynchronous resets are generally specified as being ideal during synthesis. It is the responsibilty of the layour engineers to lay the clock tree and the reset tree so that the skew is within limits and that the circuit meets timing. However my question is: How are synchronous reset nets dealt with during synthesis? (...)