GDS MILL USER MANUAL
Contents
1. of cadence into a GDS to work with creater a streamer object to interact with the cadence libraries streamer gdsMill GdsStreamer O CON DU BWN FP use the streamer to take a cadence layout and convert it to GDS 2 for us to work with 10 the GDS will be named testLayoutA gds 11 streamer streamFromCadence cadenceLibraryContainerPath design 600nmAmi 12 libraryName gdsMillTest 15 cellName testLayoutA 14 outputPath gdsFiles 15 16 next load our base cell layout from the GDS generated above 17 arrayCellLayout gdsMill VlsiLayout 18 reader gdsMill Gds2reader arrayCelllayout 19 reader lLoadFromFileC gdsFiles testLayoutA gds 21 since we will be streaming into the same Library that testLayout came from 22 let s rename it here so that we don t overwrite accidentally later 23 arrayCellLayout rename arrayCell Lines 25 through 53 create the layout array First an empty top level layout is created in line 28 Notice that a name is assigned in the constructor which will be the name of the final cellView when streamed back into Cadence A nested loop is setup in line 43 and 44 Lines 46 through 48 are included to demonstrate mirroring that might be performed in a typical memory com piler Every other instance is mirrored about its X axis Line 49 performs the actual instantia tion of arrayCellLayout into newLayout At the end of the nested loops there will be 100 ins2. 0 6 CDK 1 1 cd design 600nmAmi 1 2 source 600nmAmi cshrc 1 3 icfb amp Create a new library to work in 2 1 CIW gt Tools gt Library Manager 2 2 File gt New gt Library 2 3 Enter gdsMillTest as the name 2 4 Choose Attach To An Existing Techfile 2 5 Select NCSU_TechLib_ami06 as the technology library Create a new layout to process using GDS Mill still using library manager 3 1 File gt New gt Cellview 3 2 Enter testLayoutA and the Cell Name and choose Virtuoso as the Tool 3 3 Double click on the newly created layout file in the library manager to open Virtuoso Create some shapes in the layout An example is shown below where three NFET instances are placed a Metall box is drawn paths are added in Metall and Metal2 and a contact is added VLSI TOOLS GDS MILL USER MANUAL N SOO ANAWA GOQDOOODOOOC EEE wa N 5 Save and close the layout window The GDS Mill Quick Start Script The quick start script is located in the exampleUserDir directory It gives a step by step example of using GDS Mill to export a layout from Cadence modify it stream the modified layout back into Cadence and then output a PDF file of the modified layout To run the script 1 cd design 600nmAmi 2 edit quickStart py so that the paths are real For example replace design 600nm Ami with an actual path such as users me home design 600nmA
3. V L S I T O O L S www vlsitools com GDS MILL USER MANUAL Version 1 0 AUTHOR Michael Wieckowski CONTACT wieckows umich edu www vlsitools com Introduction What is GDS Mill While GUI interfaces are typically well suited to designing VLSI layouts there do exist many tasks where a Scripted approach is the most efficient A few common examples are the tiling of memory cells in the compilation of a cache array the filling of a top level layout to meet density require ments and the striping of a top level power grid In these instances one often wants to include parametrization to enable painless engineering changes during the design cycle To do this script ing large portions of the layout simply makes the most sense GDS Mill is a framework for scripting VLSI layouts in Python GDS Mill was designed from the ground up to be user friendly highly extensible and widely appli cable without sacrificing ability or efficiency In short I want you to use it and use it painlessly GDS Mill is based on the industry standard binary GDSII file format as its input output and inte grates nicely with the Cadence design suite Using GDS Mill you can stream GDS layouts to and from Cadence create layouts from scratch or modify existing layouts all with only a handful of code in Python Why Python 1 Available on almost every platform including Windows and OS X Free 2 Quick learning curve 3 Easy to read 4 Powerful dynam
4. ce from a generated block to an existing shape blockSize is a float of layout units to specify the size square of the generated blocks e Return None VLSI TOOLS GDS MILL USER MANUAL 19 PdfLayout Class This class is used for visualization of VlsiLayout objects It makes use of the PyX framework to translate GDS Primitives into lines shapes and colors in PDF format Relevant properties layout e Description e A VisiLayout object to be drawn in the PDF layerColors e Description e Adictionary whose keys are layer numbers and values are hex strings representing RGB color values e Be sure to populate this dictionary for at least 1 layer e For example layerColors 7 FFFF e Default e Empty scale e Description e A float that scales the size of the output PDF e Since most layouts are thousands of layout units in size coordinates are DIVIDED by this scale value in order to keep the PDF size reasonable e Default e 1 0 Relevant methods init_ theLayout e Description e Constructor method e Arguments e theLayout is the VlsiLayout object to be converted to PDF format e Return None drawLayout e Description e Once everything else is setup colors assigned layout connected this method goes through and draws the actual layout shapes into an internal buffer e Arguments None e Return None write ToFile fileName e Description e Outputs a PDF version of the layout to the spec
5. f the generated text Default is 0 0 magnification is the float size of the generated text Default is 0 1 rotate is a float containing the angle of rotation Common values are 180 0 and 90 0 Default is None updatelnternalMap is a boolean specifying whether or not to update the internal flat representation of the layout This flat version is required for visualization such as ex porting to PDF and for certain geometric operations such as density filling For a given layout this internalMap only needs to be updated once Default is False e Return None fillAreaDensity layerToFill offsetInMicrons coverageWidth coverageHeight minSpacing blockSize e Description Adds many blocks of a particular layer to the layout while maintaining a specified dis tance from any existing shapes Will take into account all levels of hierarchy even when invoked at the highest level of hierarchy e Arguments layerToFill is an integer value corresponding to a particular layout layer Refer to layer NumbersInUse to see which layer numbers are currently used in the layout Any valid layer is acceptable offsetInMicrons is a tuple of x y coordinates in layout units that allows nudging of the filled layout by specifying the center of the area to be filled coverageWidth and coverageHeight are the float dimensions of the area to be filled cen tered around the offset above minSpacing is a float of layout units to specify the minimum distan
6. ic types object oriented 5 Feature rich libraries free IDE s and much more GDS Mill Features GDS Mill s first release 1 0 contains all the necessary tools to do layout scripting for most ap plications 1 Read and write binary GDSII files 2 Stream to and from Cadence using PIPO 3 Create basic layout shapes including boxes paths and text 4 Instantiate one layout within another to create hierarchical designs 5 Perform basic area filling operations GDS Mill is being developed rapidly and new features are being added daily In addition I welcome any feedback and feature requests from the VLSI community so don t hesitate to ask if you think function X is a must have VLSI TOOLS GDS MILL USER MANUAL setup Process technology independence and user independence is a MUST for any successful VLSI project To that end I recommend setting up your design environment as shown in the following figure In essence all design kits and tools are installed in isolated locations to be shared among all users Each user maintains separate directories for each of their projects where each directory has a shell script to link the required tools for that project only The following setup instructions for GDS Mill are based on this model lt S gt x Tools Installing Python Since GDS Mill is a tool for layout scripting in Python it requires a recent version of Python to be installed 2 4 or higher Most linux distributions
7. ified filename e Arguments e fileName is the string path to the PDF file to be generated e Return None VLSI TOOLS GDS MILL USER MANUAL 20
8. l data bus etc 55 newLayout addPath layerNumber newLayout layerNumbersInUse 7 56 coordinates 20 0 0 0 25 0 0 25 0 10 0 57 width 1 0 58 updatelnternalMap False 59 add some text that in a real example might be an I O pin 60 newLayout addText text Hello 61 LayerNumber newLayout layerNumbersInUse 5 62 offsetInMicrons 0 0 63 magnification 1 64 rotate None 65 updatelnternalMap True 66 Lines 67 through 73 perform the same GDS export and stream in operations as seen in the Quick Start example above 67 and now dump the filled layout to a new GDS file VLSI TOOLS GDS MILL USER MANUAL 12 68 writer gdsMill Gds2writer newLayout 69 writer writeToFileC gdsFiles arrayLayout gds 70 and stream it into cadence 71 streamer streamToCadence cadenceLibraryContainerPath design 600nmAmi 72 libraryName gdsMillTest EE inputPath gdsFiles arrayLayout gds VLSI TOOLS GDS MILL USER MANUAL 13 Layer Fill Example The filler demo script is located in the exampleUserDir directory It gives a step by step example of performing a layer fill on top of an existing layout This step is typically required towards the end of a VLSI design cycle to satisfy density requirements for fabrication BE SURE TO EDIT THE PATHS IN THE EXAMPLE SCRIPT TO MATCH THE ACTUAL PATHS USED IN YOUR SYSTEM Lines 1 through 9 perform the same setup to read in a GDSII layou
9. layout object now contains all of the elements of the layout 27 let add a box to the layout 28 myLayout addBox LayerNumber myLayout LayerNumbersInUse Q pick some layer 29 offsetInMicrons 10 0 location VLSI TOOLS GDS MILL USER MANUAL 30 width 10 0 units are microns 31 height 5 0 32 updateInternalMap True This is important for visualization see note 1 below 33 center True origin is in the center or the bottom left corner 34 Note 1 the layout object keeps track of its elements in a 2D map no hiearachy 35 this makes visualization more efficient Therefore to do a PDF output or some other 36 flat output you need to update the internal map of the layout object Only do this 37 ONE TIME after all the objects you are manipulating are fixed Lines 39 through 49 stream our modified layout back into Cadence This first thing we do is change the name if we didn t our original layout might be overwritten We then create a Gds2writer object in exactly the same way as the Gds2reader earlier Line 44 exports the layout to a GDS2 file which we use in line 46 to stream back into Cadence 39 let s take out new layout and stream it back into a cadence library 40 first create a new GDS 41 we change the root structure name this will be the cellview name upon stream in 42 myLayout rename testLayoutB 43 writer gdsMill Gds2writer myLayout 44 writer writeToFile gdsFiles testLayo
10. mi 3 source gdsMill cshre 4 python quickStart py Let s go over the script piece by piece to learn the basics of GDS Mill Lines 1 and 2 of the script simply import the gdsMill module into the Python environment 1 usr bin env python 2 import gdsMill 3 Lines 4 through 13 create a GdsStreamer object called streamer The streamFromCadence method is then called with several parameters to export the layout that we made earlier into a VLSI TOOLS GDS MILL USER MANUAL GDSII file The resulting file will go into the gdsFiles directory of the exampleUserDir directory and will be called testLayoutA gds creater a streamer object to interact with the Cadence Libraries streamer gdsMill GdsStreamer use the streamer to take a Cadence layout and convert it to GDSII for us to work with the GDS will be named testLayoutA gds 9 streamer streamFromCadence cadenceLibraryContainerPath design 600nmAmi 10 libraryName gdsMillTest 11 cellName testLayoutA 12 outputPath gdsFiles 13 4 3 6 7 8 Lines 14 through 25 take the GDSII file we just made and import it into a VlsiLayout object to play with in Python The object is called myLayout To do the actual import we first create a Gds2Reader object called reader in line 19 Notice that myLayout is passed in to the reader for its constructor to use In like 24 we tell reader to fill the layout object myLayou
11. o the center of the rectangle or the bottom left corner Default is False Return None addPath layerNumber coordinates width updatelnternalMap Description VLSI TOOLS GDS MILL USER MANUAL 18 Adds a geometric path to the layout using the given parameters e Arguments layerNumber is an integer value corresponding to a particular layout layer Refer to lay erNumbersInUse to see which layer numbers are currently used in the layout Any valid layer is acceptable coordinates is a list of tuples of x y coordinates in layout units that sets the shape of the generated path width is the float width of the path in layout units updatelnternalMap is a boolean specifying whether or not to update the internal flat representation of the layout This flat version is required for visualization such as ex porting to PDF and for certain geometric operations such as density filling For a given layout this internalMap only needs to be updated once Default is False addText text layerNumber offsetInMicrons magnification rotate updatelnternalMap e Description Adds a geometric text string to the layout using the given parameters e Arguments layerNumber is an integer value corresponding to a particular layout layer Refer to lay erNumbersInUse to see which layer numbers are currently used in the layout Any valid layer is acceptable offsetInMicrons is a tuple of x y coordinates in layout units that sets the position o
12. ocal file that you will source every time you want to use the design kit For my case using CSHELL 3 1 cd design 600nmAmi 3 2 for vi use vi 600nmAmi cshrc Alternately use your favorite editor 3 3 Enter the following lines into the file changing the paths where appropriate setenv SYSTEM_CDS_LIB_DIR tools ic 5 141_usr5 tools dfII samples setenv CDSHOME tools ic 5 141_usr5 setenv CDK_DIR design common ncsu cdk 1 5 1 setenv CDS_MMSIM_DIR tools mmsim 7 0 setenv CDS _INST_DIR tools ic 5 141_usr5 4 Now we need to copy a few files for GDS Mill Take a look in the design common GDSMill exampleUserDir This directory contains what a typical work directory might look like to GDSMill For this setup let s just copy it all into our work directory 4 1 cp r design common GDSMill exampleUserDir design 600nm Ami VLSI TOOLS GDS MILL USER MANUAL 42 cd design 600nmAmi 4 3 Edit the gdsMill cshrc file according to the instructions inside The most important variables to set are PATH and PYTHONPATH Without these you will likely have the wrong version of Python running and your scripts will not know where to find GDS Mill VLSI TOOLS GDS MILL USER MANUAL Quick Start Example Create A Layout In Cadence This section can be skipped if you want to just use a GDS file that already exists A sample GDS file is included in the exampleUserDir directory 1 Start Cadence using the NCSU AMI
13. only with the rename method e Default e None Relevant methods __init_ self name units libraryNamej gdsVersion e Description e Constructor method e Arguments e name isa string that can be used to initialize the rootStructure name See rootStruc tureName above e units is a tuple that maps layout units to physical units VLSI TOOLS GDS MILL USER MANUAL 17 e libraryName is the name of the Library that the layout was generated from Irrelevant for streaming back into Cadence e gdsVersion is the file format version for GDSII Default is 5 Return None rename newName Description e Changed the name of the root structure object This will effectively rename the top level of the layout which effects the cellView name upon import to Cadence Arguments e newName is a string holding the new top level name Return None addInstance layoutToAdd offsetInMicrons mirror rotate updatelnternalMap Description e Adds an instance of VlsiLayout to the current layout This allows one to create hierarchy within generated layouts Arguments e layoutToAdd is a VlsiLayout object describing the layout to instantiate e offsetInMicrons is a tuple of x y coordinates in layout units that sets the position of the instantiated layout Default is 0 0 e mirror is a string of GDS mirror properties Possible values are x y xy Default is None e rotate is a float containing
14. orm this action twice to fill two different layers using varied spac ing box size etc gt 30 31 32 33 34 now actaully add the fill gds mill will create an array of boxes maintaining spacing from existing layout elements we ll do it once for two different layers filledLayout fillAreaDensity layerToFill myTopLevellayout layerNumbersInUse 5 offsetInMicrons 10 0 10 0 this is where to start from coverageWidth 40 0 size of the fill area in microns coverageHeight 40 0 minSpacing 0 5 distance between fill blocks blockSize 2 0 width and height of each filler block in microns filledLayout fillAreaDensity layerToF1LL myTopLeveLLayout LayerNumbersInUse 7 offsetInMicrons 11 0 11 0 this is where to start from coverageWidth 40 0 size of the fill area in microns coverageHeight 40 0 minSpacing 0 5 distance between fill blocks blockSize 3 0 width and height of each filler block in microns Lines 46 through 53 dump the top level filled layout to a GDS file and stream it back into the original Cadence library Refer to the Quick Start example for more details 46 and now dump the filled layout to a new GDS file 47 writer gdsMill Gds2writer filledLayout 48 writer writeToFile gdsFiles filledLayout gds 49 and strea 50 streamer gdsMill GdsStreamer 51 streamer streamToCadence cadencelLibraryContainerPath design 600nmAmi 52 libraryName gd
15. rsInUse 3 E9C514 65 visualizer LayerColors myLayout LayerNumbersInUse 4 856FQ0 VLSI TOOLS GDS MILL USER MANUAL 66 visualizer LayerColors myLayout LayerNumbersInUse 5 BD1444 67 68 set the scale so that our PDF isn t enormous 69 visualizer setScale 500 70 tell the pdf layout object to draw everything in our layout 71 visualizer drawLayout 72 and finally dump it out to a file 73 visualizer writeToFileC gdsFiles gdsOut pdf VLSI TOOLS GDS MILL USER MANUAL 10 Array Example The array demo script is located in the exampleUserDir directory It gives a step by step exam ple of using GDS Mill to instantiate a Cadence layout inside of a newly created layout The in stances are placed in an array along with some top level shapes and texts These steps demon strate the true power of scripting layout generation with GDS Mill tasks such as memory com pilation power grid generation etc can be implemented quickly with high extensibility BE SURE TO EDIT THE PATHS IN THE EXAMPLE SCRIPT TO MATCH THE ACTUAL PATHS USED IN YOUR SYSTEM Lines 1 through 24 stream the layout that we want to instantiate into a VlsiLayout object called arrayCellLayout These steps were all covered in the Quick Start example usr bin env python import gdsMill we are going to make an array of instances of an existing layout assume that we designed the base cell in cadence step 1 is to stream it out
16. sMillTest 5 inputPath gdsFiles filledLayout gds VLSI TOOLS GDS MILL USER MANUAL 15 Class Reference GdsPrimitives Module This module contains a group of class definitions for the various elements that comprise a GDSII file These include structures boundaries paths structure references array references text nodes and boxes Relevant methods rotatedCoordinates rotateAngle e Implemented in GdsBoundary GdsPath e For geometric elements whose coordinates are specified relative to their origin this helper method rotates these coordinates by an arbitrary angle e Arguments rotateAngle is a numeric float int angle in degrees e Returns A list of x y pairs representing the rotated coordinates equivalentBoundaryCoordinates rotateAngle e Implemented in GdsPath e Since a path s coordinates only define its points along it s center this method uses the pathWidth property to convert the path coordinates into a list of boundary coordinates This list effectively draws the outline of the path and is used for visualizing the path for ex ample as a PDF element e Arguments rotateAngle is a numeric float int angle in degrees e Returns A list of x y pairs representing the rotated boundary equivalent coordinates Gds2reader Class Relevant methods _ init_ layoutObject debugToTerminal e Description e Constructor method e Arguments e layoutObject is an object of type VisiLayout that the reader
17. t with data from our GDSII file by calling the method loadFromFile and passing it a valid path At this point the myLayout object knows everything about the shapes and properties of our lay out and we are no longer in the world of GDS 14 create a Layout object this object represents all of the elements within the Layout 15 myLayout gdsMill VlsiLayout 16 17 give our layout object to a gds reader object The gds reader will look at the binary gds 2 file and 18 populate the Layout object with the file s contents 19 reader gdsMill Gds2reader myLayout 20 21 tell the reader object to process the gds file that we streamed in above 22 un comment the next line to see some details about the gds contents 23 reader debugToTerminal 1 24 reader loadFromFile gdsFiles testLayoutA gds 25 Lines 26 through 38 perform some modification on our layout As a simple example we are just going to add a box to the layout using the addBox method For the layerNumber we simply tell it to use the first layer specified in the original layout In a real example you would specify a meaningful number here to correspond to a particular layer i e 7 metall Also notice that in line 32 the internal map is updated This is because we don t plan to add any other shapes to the layout and we want to visualize it as a PDF later Therefore we want our newly added box to be updated in the internal flat map 26 our
18. t as in the Quick Start exam ple We assume in this case the the gds has already been streamed out either via GDS Mill or the Cadence CIW usr bin env python import gdsMill we will add the filler at a higher level of hiearchy so first load our top level layout from GDS myTopLevelLayout gdsMill VlsiLayout reader gdsMill Gds reader myTopLevelLayout reader LoadFromFileC gdsFiles testLayoutA gds O CON MU BWN FE Since we don t want to add fill directly to our existing layout we will create another level of hi erachy on top of it Lines 10 through 28 create a new top level layout and drop in an instance of the existing layout into it 10 now create a new layout 11 be sure to assign a name since this will be the root object in our hierarchy to which 12 fall other objects are referenced 13 filledLayout gdsMill VlLsiLayout name filledLayout 14 15 now place an instnace of our top level layout into the filled layout 16 hierarchy looks like this 17 filled layout 18 top Level Layout 19 Layout elements 20 Layout elements 21 layout elements 22 fill elements 23 fill elements 24 filledLayout addlnstance myTopLevelLayout 25 offsetInMicrons 0 0 26 mirror 27 rotate 0 0 28 VLSI TOOLS GDS MILL USER MANUAL 14 Lines 29 through 45 perform the actual fill operation by calling the fillAreaDensity method on the top level layout We perf
19. tances placed in a grid spaced by 10 microns in the x direction and 15 in the y VLSI TOOLS GDS MILL USER MANUAL 11 25 now create a new layout 26 be sure to assign a name since this will be the root object in our hierarchy to which 27 all other objects are referenced 28 newLayout gdsMill VlsiLayout name arrayExample 30 now place an instnace of our top level layout into the filled layout 31 hierarchy looks like this 32 array example 33 4 array cell layout 34 layout elements 35 layout elements 36 layout elements 37 cell instance 38 cell instance 39 cell instance 40 connection elements 41 42 now create the array of instances 43 for xIndex in range 0 10 44 for ylndex in range 0 10 45 if CyIndex 2 0 46 mirror MX 47 else 48 mirror RQ 49 newLayout addlnstance arrayCel LLayout 50 offsetInMicrons xIndex 10 0 ylIndex 15 0 51 mirror mirror 52 rotate 0 0 53 A typical layout design will need to connect the previously placed instances together in some way Lines 54 through 66 create a path and a text element in the top level layout They could be rolled into a loop and parameterized in a variety of ways to effectively create top level metalli zation with pins Noticve that the internal map is updated in line 65 since this is the last ele ment we add to the layout 54 add a wire that in a real example might be a power rai
20. the angle of rotation Common values are 180 0 and 90 0 Default is None e updatelnternalMap is a boolean specifying whether or not to update the internal flat representation of the layout This flat version is required for visualization such as ex porting to PDF and for certain geometric operations such as density filling For a given layout this internalMap only needs to be updated once Default is False Return None addBox layerNumber offsetInMicrons width height updateInternalMap center Description e Adds a geometric rectangle to the layout using the given parameters Arguments e layerNumber is an integer value corresponding to a particular layout layer Refer to lay erNumbersInUse to see which layer numbers are currently used in the layout Any valid layer is acceptable e offsetInMicrons is a tuple of x y coordinates in layout units that sets the position of the generated rectangle Default is 0 0 e width is the float width of the rectangle in layout units e height is the float height of the rectangle in layout units e updatelnternalMap is a boolean specifying whether or not to update the internal flat representation of the layout This flat version is required for visualization such as ex porting to PDF and for certain geometric operations such as density filling For a given layout this internalMap only needs to be updated once Default is False e center is a boolean determining if the offset is relative t
21. utB gds 45 46 streamer streamToCadence cadenceLibraryContainerPath design 600nmAmi 47 libraryName gdsMillTest 48 inputPath gdsFiles testLayoutB gds 49 Lines 50 through 73 create a PDF view of our modified layout We first create a PdfLayout ob ject called visualizer and we pass in our layout to its constructor In lines 61 through 66 we assign hexadecimal colors to the first 6 layers of our layout By using the layerNumbersInUse property we don t need to know the actual layer numbers The scale is set to 1 500 in line 69 to reduce the size of the PDF file Lines 71 through 73 finally draw the layout and export it to a file 50 let s create a PDF view of the layout object 51 first create the object to represent the visual output 52 visualizer gdsMill PdfLayout myLayout 53 54 since we have no knowledge of what the layer numbers mean for this particular technology 55 we need to assign some colors to them 56 57 uncomment the following line if you want to actually see the layout numbers in use 58 print myLayout LayerNumbersInUse 59 60 for each layer number used in the layout we will asign it a layer color as a RGB Hex 61 visualizer LayerColors myLayout LayerNumbersInUse Q 219E1C 62 visualizer LayerColors myLayout LayerNumbersInUse 1 271C9E 63 visualizer LayerColors myLayout LayerNumbersInUse 2 CC54C8 64 visualizer LayerColors myLayout LayerNumbe
22. voiding any IP issues GDS Mill will work with ANY technology The following steps were used to install the NCSU CDK on my system yours might be different so read carefully 1 Register and download the CDK from http www eda ncsu edu wiki NCSU CDK download 2 I consider it good practice to keep the CDK itself in a central location that is referenced by each user s working directory Untar Unzip the downloaded CDK into your central loca tion For my case 2 1 cp ncsu cdk 1 5 1 tar gz design common 2 2 cd design common 2 3 tar xvvzf ncsu cdk 1 5 1 tar gz VLSI TOOLS GDS MILL USER MANUAL Setup a directory to work from Your working directory will be the location where you run GDS Mill Cadence etc In this man ual we will setup the working directory to use the NCSU CDK installed above 1 Create a directory specific to the process node you want to use In my case this will be AMI Semiconductor 0 6 micron process 1 1 mkdir design 600nmAmi 2 Copy the CDS initialization and library files from the CDK common directory into your working directory 2 1 cp design common ncsu cdk 1 5 1 cdsinit design 600nmAmi 2 2 cp design common ncsu cdk 1 5 1 cdssetup cds lib design 600nmAmi 3 The files we copied in step 2 rely on some environment variable to work properly Since these variables are specific to the NCSU CDK we will NOT put them in our global shell ini tialization file Instead make a l
23. will have a version of Python installed for you to use but the version may not be recent enough Luckily you can install a local copy of Python on top of any existing installations if the machine you want to run on doesn t meet the requirements I rec ommend installing a copy of Python 2 6 locally as follows 1 Download Python via SVN and decompress it as follows 1 1 cd some tempPath 1 2 wget http www python org ftp python 2 6 1 Python 2 6 1 tgz 1 3 tar xvzf Python 2 6 1 tgz 2 Install Python into your home directory or a project directory 2 1 cd some tempPath Python 2 6 1 2 2 configure prefix some localPath forPython toReside 2 3 make VLSI TOOLS GDS MILL USER MANUAL 2 4 make install Installing GDS Mill These instructions will install GDS Mill into a central location 1 Download the GDS Mill zip from http www vlsitools com 2 mkdir design common GDSMilI 3 mv download location GdsMill_1 0 zip design common GDSMill 4 cd design common GDSMill 5 unzip GdsMill_1 0 zip 6 rm GdsMill_1 0 zip The remainder of the installation involves copying and modifying the shell script in design common GDSMill exampleUserDir This is covered in the section Setup a directory to work from below Installing the NCSU CDK All the examples in this manual are based on the NCSU Cadence Design Kit Since it is freely available it is a good platform to introducing GDS Mill while a
24. will populate with informa tion from a GDSII file e debugToTerminal is an optional parameter that can be set to 1 or 0 where 1 will print GDS specific information on the terminal as files are read e Return None loadFromFile fileName e Description e When called reads the contents of a binary GDSII file and populates the attached VLSI Layout object with GDSPrimitives objects e Arguments e fileName is an absolute string path to a binary GDS 2 file e Return None VLSI TOOLS GDS MILL USER MANUAL 16 Gds2writer Class Relevant methods init_ layoutObject e Description e Constructor method e Arguments e layoutObject is an object of type VisiLayout that the write will use to generate a binary GDSII file e Return None write ToFile fileName e Description e When called writes the elements of a VLSILayout object to a binary GDSII file e Arguments e fileName is an absolute string path to the binary GDS 2 file to be created e Return None VisiLayout Class Relevant properties units e Description e A tuple that maps layout units to physical units e Default e 0 001 1e 9 which corresponds to 1 layout unit 1 micron layerNumbersInUse e Description e A list of all layer number currently in the layout rootStructureName e Description e A string holding the name of the top most structure in the layout hierarchy This is also used as the cellView name upon import export to Cadence Change this
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