Support for LTspice A type models (Schmitt, OR, AND, ext)?

QSPICE
1

I have a model file that uses LTspice A type models like OR, AND, and other logic gates. It seems like these may not be currently supported by Qspice. Is there a plan to support these in the future? As an alternative approach I attempted to substitute A type models with Qspice behaviorial components but got a similar error. Can anyone provide insight into the best way to handle this issue I am having?

Thanks
Ravi

2

I wrote the LTspice A-devices over 25 years ago over a three day week end. It was one of my first mixed-mode simulators. I’ve moved on from that method and QSPICE is free of that method. My guess is that the LTspice A-devices will remain proprietary to LTspice.

–Mike

3

Mike,

I agree with not wanting to go back to the past. As an alternative I attempted to modify the model file and replace the LTspice logic gates with the Qspice equivalent. Below is an example of how i tried to translate the XOR gate. The below statements are my version of templates to map the right ports. There are other logic gates in the full model but I am trying to take it step by step. These statements are inside of a subcircuit.

LTspice Template Netlist
*Axxx 0 XOR_IN1 0 XOR_IN2 0 XNOR_OUT XOR_OUT 0 XOR

Qspice Template Netlist
*¥6 VDD VSS XOR_OUT XNOR_OUT XOR_IN1 XOR_IN2 ¥ ¥ ¥ ¥ ¥ ¥ ¥ ¥ ¥ ¥ XOR

When I try the utilize Qspice template i get the error

Fatal error: Unknown device type: â

Is this an approach I should be able to make work?
I can send you the whole model file if you would prefer that

4

That’s the right approach, I would guess.

To understand the error, you’d want to find a line in the netlist that uses the ‘â’ character.

QSPICE doesn’t use that character.

–Mike

5

CD4046Bg.txt (4.6 KB)

I attached the whole model file so you can see the context of the approach I took.
I only commented out the single line for Y6 for the XOR gate so this is the line that is creating the Fatal Error. I am just not sure why its complaining about this syntax

6

I copied and pasted that special character (Y) from the auto generated netlist from QSPICE when I ploped examples on a schematic page. Maybe this was a mistake. Let me know how this line might need to change to be syntax correct

7

When I open CD4046.txt in my text editor, I see

image

That is, it has the ‘Â’ character. In the error message, it was reported in lower case: ‘â’

So remove those characters and you should get farther along.

–Mike

8

Thanks Mike,

When I open the file in Notepad++ the default encoding is UTF-8. This encoding did not display the  character. In Notepad++ when I changed to Encoding->ANSI then that  special character is now visible. I removed all instances of that special character and the simulation compiles properly and shows me a waveform viewer

9

You can also open the file in QSPICE (QUX.exe) It includes an ASCII editor for the type of ASCII QSPICE reads.

–Mike