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| | By Syed Haider | | By Syed Haider |
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| | + | == Note == |
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| − | == Setting Up Standard Cell Library and Project Directory ==
| + | We had a tutorial on how to use PrimeTime Power Estimation here, but we were informed that this might violate the EULA as provided by Synopsys for the University Program. |
| − | 1. Download Oklahoma State University Library from http://vcag.ecen.okstate.edu/projects/scells/
| + | |
| | | | |
| − | Specifically, from: http://vcag.ecen.okstate.edu/projects/scells/download/iit_stdcells_v2.3beta/
| + | If you would like to see this tutorial, please contact support@ece.vt.edu |
| − | | + | |
| − | Download the iitcells_lib_2.3.tar.gz package.
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| − | | + | |
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| − | 2. untar the library somewhere nice like your home directory where you will really never touch it (i.e. /home/syedh/). The Directory will be called iit_stdcells.
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| − | 3. Create a project directory somewhere else. (example: mkdir /home/syedh/Project1)
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| − | In Project1 create another directory called WORK.
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| − | 4. Back in Project1 directory create an empty file called: '''.synopsys_dc.setup'''
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| − | | + | |
| − | This file will specify to Synopsys and design_vision software what libraries you are using. A sample version of the file is listed below. The path after “/home/syedh/” should remain unchanged if this tutorial is being followed correctly!!!
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| − |
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| − | # .synopsys_dc.setup file
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| − | # Define the target tehcnology library, symbol library,
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| − | # and link libraries
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| − | set target_library /home/syedh/iit_stdcells/lib/tsmc018/lib/iit018_stdcells.db
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| − | #do not have a symbol library
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| − | #set symbol_library
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| − |
| + | |
| − | #set link library (set as same as target library)
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| − |
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| − | set link_library “/home/syedh/iit_stdcells/lib/tsmc018/lib/iit018_stdcells.db *”
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| − |
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| − | set designer "Your Name"
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| − | 5. Copy /home/syedh/iit_stdcells/lib/tsmc018/lib/iit018_stdcells.v into Project1 Directory.
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| − | | + | |
| − | 6. Now it is design time. Create verilog description of something amazing. Here is a design of a full adder and some registers that spans multiple design files (full_adder.v, top.v):
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| − | //full_adder.v
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| − | //This is a module for a 1 bit Full Adder
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| − | module full_adder(a,b, c_in, s, c_out);
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| − | | + | |
| − | input a, b, c_in;
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| − | output wire s, c_out;
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| − | | + | |
| − | assign s = a ^ b ^ c_in;
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| − | assign c_out = ((a & b)) | (c_in & (a^b));
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| − | | + | |
| − | endmodule
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| − | | + | |
| − | //top.v
| + | |
| − | //This contains a full adder with some registers for input and output.
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| − | `timescale 1ns/10ps
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| − | module top (clk, a, b, c_in, sum, c_out);
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| − | | + | |
| − | input clk, a, b, c_in;
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| − | output sum, c_out;
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| − | | + | |
| − | reg in_a;
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| − | reg in_b;
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| − | reg sum_reg;
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| − | reg c_out_reg;
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| − | reg c_in_reg;
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| − | | + | |
| − | full_adder fa1(.a(in_a), .b(in_b), .c_in(c_in_reg), .s(sum), .c_out(c_out));
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| − | | + | |
| − | always @(posedge clk)
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| − | begin
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| − | in_a = a;
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| − | in_b = b;
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| − | c_in_reg = c_in;
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| − | c_out_reg = c_out;
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| − | sum_reg = sum;
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| − | end
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| − | endmodule
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| − | 7. Now it is time to create a test bench file to test the design. The things that will be highlighted in purple are system tasks that will create dumps (value change dumps) of signals in your design.
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| − | | + | |
| − | //tb_top.v
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| − | //testbench
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| − | `timescale 1ns/10ps
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| − | module tb_top();
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| − | reg clk;
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| − | reg a, b, c_in;
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| − | wire c_out, sum;
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| − | | + | |
| − | //clocking description
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| − | initial
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| − | begin
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| − | clk = 0;
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| − | end
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| − | | + | |
| − | //clock period is #100
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| − | always begin
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| − | #50
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| − | clk = ~clk;
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| − | end
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| − | //initialize input to full adder
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| − | initial begin
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| − | a = 0;
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| − | b = 0;
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| − | c_in = 0;
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| − | end
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| − | ///////////////////////////////
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| − | // Toggle the inputs at varying rates
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| − | ///////////////////////////////
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| − | | + | |
| − | //toggle carry_in
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| − | initial begin
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| − | #60;
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| − | repeat (50)
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| − | begin
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| − | c_in <= ~c_in;
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| − | #100;
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| − | end
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| − | end
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| − | | + | |
| − | //toggle a
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| − | initial begin
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| − | #60;
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| − | repeat (25)
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| − | begin
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| − | a <= ~a;
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| − | #200;
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| − | end
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| − | end
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| − | | + | |
| − | //toggle b and setup vcd dump
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| − | initial begin
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| − | $dumpfile("dmp_top.vcd"); //read verilog book for more info on system command
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| − | $dumpvars(0,top);
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| − | #60;
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| − | $dumpon;
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| − | repeat (10)
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| − | begin
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| − | b <= ~b;
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| − | #500;
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| − | end
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| − | $dumpoff;
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| − | $finish; //ends simulation
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| − | end
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| − | | + | |
| − | //Module under test
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| − | top uut(.clk(clk), .a(a), .b(b), .c_in(c_in), .sum(sum), .c_out(c_out));
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| − | endmodule
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| − | 8. Now comes the time to create a synthesized top level design from {full_adder.v top.v}. We are interested in creating a synthesized version of “top”. At command prompt type the following:
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| − | | + | |
| − | Synopsys
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| − | design_vision
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| − | Now a design_vision gui has started up. In this gui follow these steps:
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| − | | + | |
| − | In Menu: File --> Analyze.
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| − | A Dialog box will appear called “Analyze Designs”. Click the “Add..” button and add every design file {full_adder.v top.v}. You can do this one file at a time or all at one time by using the CTRL key to select multiple files. After adding all the files press OK.
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| − |
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| − | In Menu: Design --> Elaborate.
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| − | A Dialog box will appear called “Elaborate Designs”. There will be a drop down selection menu called “Design”. In this selection menu there will be two objects listed: top(verilog) and full_adder(verilog). Make sure that top(verilog) is selected. Press OK.
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| − |
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| − | Now in the Design Vision the “Hier 1” window will have objects listed in it.
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| − |
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| − | In Menu: Design --> Compile. In the dialog box that shows up press OK.
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| − |
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| − | In Menu: File --> Save As. Save the design as a verilog design with a new name (ex. top_syn.v).
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| − | 9. Exit the gui and in the command prompt type exit to quit out of the design_vision_xg_t shell. Then type exit again to quit Synopsys.
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| − | 10. Now it is time to simulate the synthesized design, top_syn.v, with the testbench, tb_top.v. The verilog simulator program of Synopsys is called VCX. The first step is to write a script for the simulation:
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| − | #vcs_script.scr
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| − | #This is a script file for VCX simulator
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| − | ./tb_top.v
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| − | ./top_syn.v
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| − | -v ./iit018_stdcells.v
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| − | +libext+.v +nolibcell +define+VPD+SAIF+VCD+SDF
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| − | 11. At command prompt type: Synopsys
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| − | Now type: vcs -f vcs_script.scr
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| − | The result of running this command is that an executable called simv is created.
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| − | 12. Run simv : ./simv
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| − | 13. Now the file dmp_top.vcd has been created.
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| − | 14. Now we will use a tool called PrimeTime-Px to get power estimation. The following script called power.scr will be used.
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| − | #power.scr
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| − | set power_enable_analysis TRUE
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| − | set target_library "/home/syedh/iit_stdcells/lib/tsmc018/lib/iit018_stdcells.db"
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| − | set link_library "/home/syedh/iit_stdcells/lib/tsmc018/lib/iit018_stdcells.db *"
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| − | | + | |
| − | read_db $target_library
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| − | read_verilog top_syn.v
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| − | current_design test_inverter
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| − | link
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| − | read_vcd dmp_top.vcd -strip_path tb_top/uut
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| − | create_power_waveforms –output vcd
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| − | report_power
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| − | 15. At the Synopsys command prompt type: pt_shell
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| − | Now run the power.scr: source power.scr
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| − | 16. If all went right the output from the script should look something like this:
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| − | ======================================================================
| + | |
| − | Summary:
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| − | Total number of nets = 11
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| − | Number of annotated nets = 11 (100.00%)
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| − | Total number of leaf cells = 7
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| − | Number of fully annotated leaf cells = 7 (100.00%)
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| − | ======================================================================
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| − | | + | |
| − | Information: The waveform options are:
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| − | File name: power_waves.fsdb
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| − | File format: fsdb
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| − | Time interval: 0.01ns
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| − | Hierarchical level: all
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| − | Information: Power analysis is running, please wait ...
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| − | Information: analysis is done for time window (0ns - 5050ns)
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| − | ****************************************
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| − | Report : Event Based Power
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| − | Design : top
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| − | Version: Z-2007.06-SP3
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| − | Date : Wed Feb 13 14:34:11 2008
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| − | ****************************************
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| − | Attributes
| + | |
| − | ----------
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| − | i - Including register clock pin internal power
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| − | u - User defined power group
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| − | | + | |
| − | Internal Switching Leakage Total
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| − | Power Group Power Power Power Power ( %) Attrs
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| − | --------------------------------------------------------------------------------
| + | |
| − | io_pad 0.0000 0.0000 0.0000 0.0000 ( 0.00%)
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| − | memory 0.0000 0.0000 0.0000 0.0000 ( 0.00%)
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| − | black_box 0.0000 0.0000 0.0000 0.0000 ( 0.00%)
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| − | clock_network 3.292e-06 0.0000 0.0000 3.292e-06 (58.67%) i
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| − | register 6.722e-07 4.735e-07 4.822e-10 1.146e-06 (20.42%)
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| − | combinational 8.640e-07 3.086e-07 4.037e-10 1.173e-06 (20.90%)
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| − | sequential 0.0000 0.0000 0.0000 0.0000 ( 0.00%)
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| − | | + | |
| − | Net Switching Power = 7.821e-07 (13.94%)
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| − | Cell Internal Power = 4.828e-06 (86.05%)
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| − | Cell Leakage Power = 8.859e-10 ( 0.02%)
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| − | ---------
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| − | Total Power = 5.611e-06 (100.00%)
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| − | | + | |
| − | X Transition Power = 0.0000
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| − | Glitching Power = 2.152e-08
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| − | | + | |
| − | Peak Power = 4.726e-03
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| − | Peak Time = 550.100
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Power Estimation with OSU Standard Cell Library and Synopsys tools (PrimeTime-Px)
We had a tutorial on how to use PrimeTime Power Estimation here, but we were informed that this might violate the EULA as provided by Synopsys for the University Program.
