From a303d263e33ad54de89aefc2d96421e67424ec15 Mon Sep 17 00:00:00 2001 From: Stefan Frederik Date: Tue, 18 Oct 2022 16:30:11 +0200 Subject: [PATCH] xschem manual update (xschem sky130 integration) --- doc/xschem_man/graphs.html | 2 +- doc/xschem_man/tutorial_xschem_sky130.html | 181 +++++++++++++++++++ doc/xschem_man/tutorial_xschem_sky130_01.png | Bin 0 -> 90083 bytes doc/xschem_man/tutorial_xschem_sky130_02.png | Bin 0 -> 69694 bytes doc/xschem_man/tutorial_xschem_sky130_03.png | Bin 0 -> 50874 bytes doc/xschem_man/tutorial_xschem_sky130_04.png | Bin 0 -> 69218 bytes doc/xschem_man/tutorial_xschem_sky130_05.png | Bin 0 -> 56307 bytes doc/xschem_man/tutorial_xschem_sky130_06.png | Bin 0 -> 71623 bytes doc/xschem_man/tutorial_xschem_sky130_07.png | Bin 0 -> 58583 bytes doc/xschem_man/tutorial_xschem_sky130_08.png | Bin 0 -> 60327 bytes doc/xschem_man/tutorial_xschem_sky130_09.png | Bin 0 -> 70297 bytes 11 files changed, 182 insertions(+), 1 deletion(-) create mode 100644 doc/xschem_man/tutorial_xschem_sky130.html create mode 100644 doc/xschem_man/tutorial_xschem_sky130_01.png create mode 100644 doc/xschem_man/tutorial_xschem_sky130_02.png create mode 100644 doc/xschem_man/tutorial_xschem_sky130_03.png create mode 100644 doc/xschem_man/tutorial_xschem_sky130_04.png create mode 100644 doc/xschem_man/tutorial_xschem_sky130_05.png create mode 100644 doc/xschem_man/tutorial_xschem_sky130_06.png create mode 100644 doc/xschem_man/tutorial_xschem_sky130_07.png create mode 100644 doc/xschem_man/tutorial_xschem_sky130_08.png create mode 100644 doc/xschem_man/tutorial_xschem_sky130_09.png diff --git a/doc/xschem_man/graphs.html b/doc/xschem_man/graphs.html index 0f2f929d..730c6b62 100644 --- a/doc/xschem_man/graphs.html +++ b/doc/xschem_man/graphs.html @@ -43,7 +43,7 @@ p{padding: 15px 30px 10px;}

-

Using XSCHEM's internal graph functions

+

Using XSCHEM's internal graph functions

Xschem can now display waveforms by itself in the drawing area. in the Simulation menu there is an entry to add a graph: Add waveform graph. When this menu is pressed a box can be placed in the schematic:
diff --git a/doc/xschem_man/tutorial_xschem_sky130.html b/doc/xschem_man/tutorial_xschem_sky130.html new file mode 100644 index 00000000..ca4334ed --- /dev/null +++ b/doc/xschem_man/tutorial_xschem_sky130.html @@ -0,0 +1,181 @@ + + + +XSCHEM SKY130 INTEGRATION + + + + + +

+ + +UP + + + +

XSCHEM SKY130 INTEGRATION


+

+ To use Xschem with the Google-Skywater 130nm process (here: Sky130) The following items must be followed: +

+

+

PDK_ROOT and PDK environment variables

+

+ Xschem (via the xschemrc file) looks for a PDK_ROOT environment variable that points to the installed pdk to use. + This is expecially useful if multiple or different versions of the pdk are installed. + If the pdk is installed in /usr/local/share/pdk PDK_ROOT should be set to /usr/local/share/pdk. + For Sky130 another variable PDK tells the process variant to use (currently sky130A) + or sky130B). If PDK is unset the default sky130A will be used. + If no PDK_ROOT variable is defined xschem will look into the following locations and pick the first existing found + in the order listed below: +

+
    +
  1. /usr/share/pdk
    2. +
  2. /usr/local/share/pdk
    3. +
  3. ~/share/pdk
    4. +
+

+ If no pdk is found a warning message is displayed on the xschem launching terminal. +

+ +

Simulating a circuit with sky130 devices

+

+ The best way to quickly set up a simulation with Xschem is to look at some of the provided examples. + If you descend into the test_inv component you see a working circuit ready for simulation. +


+ One line is needed in the spice netlist to load the spice models: +

+ 
+.lib /usr/local/share/pdk/sky130A/libs.tech/ngspice/sky130.lib.spice tt
+

+ The exact path depends on the install location of the pdk as explained above. + In the picture above the TT_MODELS component takes care of generating the .lib line in the netlist. + the tt at the end of the .lib line is the process corner (tt = typical n, typical p transistors). + You can change the corner to ss, sf, fs, ff to verify your design across process variations. +

+

+ You see in the circuit a COMMANDS2 component. This component allows to enter text to specify the simulation to run, + giving simulator commands and options. + You place this component by pressing the Insert or i key, browsing into the standard xschem + devices directory and placing code_shown.sym or code.sym into the schematic. +


+ Once placed in the schematic, you may click the component, press q to edit its attributes, set the + Edit attr. listbox on the right to value and enter the simulator commands to run the simulation. + You can give a reference name to this component by setting the Edit attr. listbox to name and give it + a name that will be diplayed in the schematic. (COMMANDS2 in the example). +


+

+

+ Note in above commands a write test_inv_ngspice.raw command. This example runs simulation with both + Xyce and ngspice so the output raw file is differentiated. If you just plan to use one simulator a good suggestion is + to write a raw file with the same name as the circuit, so write test_inv.raw. +

+

+ If you select the TT_MODELS component and press q you see the reference to the PDK top library SPICE file. + The path is specified using TCL variables that have been generated by xschem when the pdk installation was looked up. + This allows to have portable schematics, no absolute path is hardcoded in the schematic files. +


+ If everything is set up correctly pressing the Netlist button or hitting the n key will produce + a spice netlist of the circuit. The netlist location is by default set to your home directory: + ~/.xschem/simulations +


+ 
+schippes@mazinga:~/x/test_open_pdks$ ls -ltr ~/.xschem/simulations/
+...
+...
+-rw-r--r-- 1 schippes schippes      3266 ott 18 15:26  test_inv.spice

+

+ You can then simulate the circuit. Select the simulator to use by clicking menu + Simulation->Configure simulators and tools and selecting (for this example) ngspice +


+ Press the Simulation button and see the ngspice running in a terminal: +


+

+

+ The default terminal used by xschem to run the simulator is xterm. I strongly suggest you to install xterm + (on ubuntu/debian Linux: sudo apt install xterm) since it is a very small package and is not a broken terminal + like most Gnome/KDE/LXDE stuff. You can however use any terminal editor by specifying the one to use in your xschemrc. + If not specified xschem defaults to xterm +

+ ## set terminal xterm
+ set terminal gnome-terminal
+
+

+

+ After completing simulation you can add into the schematic a graph (Simulation->Add waveform graph) + and a waveform reload launcher (Simulation->Add waveform reload launcher). + The launcher has a tclcommand attribute that loads the simulator data file (test_inv.raw) and + specifies the type of analysis (op, dc, ac, tran) +


+ See the manual for details +


+

+

+ +
+
+ + +