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StefanSchippers / xschem

A schematic editor for VLSI/Asic/Analog custom designs, netlist backends for VHDL, Spice and Verilog. The tool is focused on hierarchy and parametric designs, to maximize circuit reuse.
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instance value substitution in `spice_sym_def` #218

Closed rroohhh closed 10 hours ago

rroohhh commented 3 weeks ago

Hi, It seems to me that currently using instance values (like in format) is not supported in spice_sym_def. I would like to be able to do something like this in my symbol:

type=subcircuit
format="@name @@A @@B @symname"
spice_sym_def=".include @symname_@corner.txt"
template="name=x1 corner=0"

To change the spice_sym_def depending on a corner property set on a instance.

If implementing this is not desired, is there some other way to achieve this?

StefanSchippers commented 3 weeks ago

replace spice_sym_def with device_model and change symbol type from subcircuit to primitive.

type=primitive
format=...
template=...
device_model=".include @symname\\_@corner\\.txt"

note the double backslashes, they represent a single escape inside the quoted string. The first escape is needed to tell xschem the first parameter is @symname and not @symname_, the second escape tells the second parameter is @corner and not @corner.txt

inside spice_sym_def no @ substitution is done. I think I will add this feature in a next commit.

rroohhh commented 2 weeks ago

Thank you for your quick response, I finally found the time to try this and using device_model is working great. I also tested spice_sym_def together with your latest changes from fa4d4a0970fe2e46ee5c13bea034655b31196582 There I noticed the substitution is working fine for parameters specified on the instance, but I could not get @symref to get substituted. With device_model I used that in combination with tcleval to obtain pathes relativ to the symbol file location, for example like this:

type=primitive
format="@name @@GND @@DIR @@A1 @@A2 @@A3 @@A4 @@A5 @@A6 @@A7 @@A8 @@B8 @@B7 @@B6 @@B5 @@B4 @@B3 @@B2 @@B1 @@OEN 74LVC8T245_PW"
template="name=x1 corner=0 LVC8T245_A_IO=LVC8T245_IO_12 LVC8T245_B_IO=LVC8T245_IO_12 LVC8T245_IN=LVC8T245_IN_12"
device_model="tcleval(.include [set myDir [file dirname "@symref\\"]]/74LVC8T245_PW.spice
.include $myDir/74LVC8T245_PW/corner_@corner\\/models.spice
.include $myDir/74LVC8T245_PW/corner_@corner\\/LVC8T245_A_IO_@LVC8T245_A_IO\\.spice
.include $myDir/74LVC8T245_PW/corner_@corner\\/LVC8T245_B_IO_@LVC8T245_B_IO\\.spice
.include $myDir/74LVC8T245_PW/corner_@corner\\/LVC8T245_IN_@LVC8T245_IN\\.spice)"

Is there a different intended way to achieve this?

StefanSchippers commented 2 weeks ago

I made another commit to process @symref (return full path of symbol, like /a/b/c/inv.sym) as well as @symname (return only name of symbol with no .sym extension) in spice_sym_def attributes. Please test if you have a chance to do it.