User defined primitives UDPs , table, pullup, pulldown, pmos, nmos, cmos, rpmos, rnmos, rcmos, tranif0, tranif1, rtran, rtranif0, rtranif1,. Operators and expressions. Bitwise operations. Reduction operations.
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Event control. Bit and part selects. Continuous assignments. Using delay. Procedural blocks. Procedural statements. Procedural assignments.
Advanced ASIC Chip Synthesis : Using Synopsys Design Compiler and PrimeTime
Functions and tasks. Functions, tasks. Compiler directives. Major EDA Companies and their tools. For FPGA this is not there. FPGA tools are cheap. You need to buy FPGA I would say "very expensive" Its in crores!! Simpler design cycle: This is due to software that handles much of the routing, placement, and timing.
Manual intervention is less. The FPGA design flow eliminates the complex and time-consuming floorplanning, place and route, timing analysis. More predictable project cycle: The FPGA design flow eliminates potential re-spins, wafer capacities, etc of the project since the design logic is already synthesized and verified in FPGA device. Field Reprogramability: A new bitstream i. FPGA costs start from a couple of dollars to several hundreds or more depending on the hardware features.
Using Synopsys® Design Compiler™ and PrimeTime®
Modern FPGAs are reconfigurable both partially and dynamically. FPGAs are good for prototyping and limited production. If you are going to make boards it isn't worth to make an ASIC. Generally FPGAs are used for lower speed, lower complexity and lower volume designs. With unprecedented logic density increases and a host of other features, such as embedded processors, DSP blocks, clocking, and high-speed serial at ever lower price, FPGAs are suitable for almost any type of design. Modern FPGAs are packed with features. Using all these features designers can build a system on a chip.
Now, dou yo really need an ASIC?
In FPGA you need not do floor-planning, tool can do it efficiently. In ASIC you have do it.
Power consumption in FPGA is more. You don't have any control over the power optimization. For example, if a cell needs to use metal 2 M2 , it would create a blockage on M2 so that the ASIC tools know now to route any M2 wires in that area. You can use Klayout to view.
Navigate to the stdcells. Here is a picture of the. If you compare the. The standard-cell library also includes several files e. This file contains information about the minimum dimenisions of wires on M1 and the resistance of these wires. It also contains a table of wire capacitances with different rows for different wire widths and spacings.
The ASIC tools can use this kind of technology information to optimize and analyze the design. Finally, a standard-cell library will always include a databook, which is a document that describes the details of every cell in the library. Take a few minutes to browse through the Nangate standard-cell library databook located here:. As a reminder, the sort unit takes as input four integers and a valid bit and outputs those same four integers in increasing order with the valid bit.
The sort unit is implemented using a three-stage pipelined, bitonic sorting network and the datapath is shown below. If you have not completed the PyMTL tutorial then you might want to go back and do that now. Basically the MinMaxUnit should look like this:. The --test-verilog command line option tells the PyMTL framework to first translate the sort unit into Verilog, and then important it back into PyMTL to verify that the translated Verilog is itself correct.
After running the tests we use the sort unit simulator to do the final translation into Verilog and to dump the. Try to see how both the structural composition and the behavioral modeling translates into Verilog. Here is an example of the translation for the MinMaxUnit.
The complicated hash suffix is used by PyMTL to make the module name unique even for parameterized modules which are instantiated for a specific set of parameters. The hash might be different for your design. Although we hope students will not need to actually open up this translated Verilog it is occasionally necessary.
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For example, PyMTL is not perfect and can translate incorrectly which might require looking at the Verilog to see where it went wrong. Other steps in the ASIC flow might refer to an error in the translated Verilog which will also require looking at the Verilog to figure out why the other steps are going wrong. While we try and make things as automated as possible, students will eventually need to dig in and debug some of these steps themselves.
This can make these. For average power analysis, we only need to know the activity factor on each net. We can use the vcd2saif tool to convert. Based on various constraints it may synthesize a ripple-carry adder, a carry-look-ahead adder, or even more advanced parallel-prefix adders. There are two important variables we need to set before starting to work in Synopsys DC. These other cells are not meant to be available for Synopsys DC to use during synthesis, but should be used when resolving references.
The next step is to turn on name mapping. When we do power analysis we will be using activity factors from RTL simulation in. There will be many nets from the RTL simulation that may not exist in the gate-level model, but ideally there will still be enough nets that are present in both the. To help this process, name mapping will keep track of how names in the RTL map to names in the gate-level model. As an aside, if you want to learn more about any command in any Synopsys tool, you can simply type man toolname at the shell prompt. We are now ready to read in the Verilog file which contains the top-level design and all referenced modules.
We do this with two commands. The analyze command reads the Verilog RTL into an intermediate internal representation. You should see three warnings related to unconnected clk and reset ports. This is because PyMTL always includes clk and reset ports even if they are not actually used in the module. You can safely ignore these warnings.
It is critical that you carefully review all warnings. There may be many warnings, but you should still skim through them. Synopsys DC will output a warning, but Synopsys DC will usually just keep going, potentially producing a completely incorrect gate-level model! We need to create a clock constraint to tell Synopsys DC what our target cycle time is. Instead, the designer gives Synopsys DC a target cycle time and the tool will try to meet this constraint while minimizing area and power. So in this example, we are asking Synopsys DC to see if it can synthesize the design to run at 3GHz i.
During synthesis, Synopsys DC will display information about its optimization process. It will report on its attempts to map the RTL into standard-cells, optimize the resulting gate-level netlist to improve the delay, and then optimize the final design to save area. The compile command does not flatten your design. Flatten means to remove module hierarchy boundaries; so instead of having module A and module B within module C, Synopsys DC will take all of the logic in module A and module B and put it directly in module C. Without extra hierarchy boundaries, Synopsys DC is able to perform more optimizations and potentially achieve better area, energy, and timing.
However, an unflattened design is much easier to analyze, since if there is a module A in your RTL design that same module will always be in the synthesized gate-level netlist. The compile command does not perform many optimizations.