On Wednesday 26 September 2007, John Doty wrote: > On Sep 25, 2007, at 1:03 AM, Amos Tibaldi wrote: > > Hello, > > I write this mail in order to obtain help if possible for > > the use of the ngspice simulator. How can I simulate the > > behaviour of a microcontroller that is present in the > > schematic of a circuit with ngspice? > > Basically, you can't. > > What I do in these situations is substitute voltage sources > for the microcontroller output pins and generate PWL stimuli > for them. Put probes where the inputs would be, .PRINT those > voltages, and use an AWK or C program to extract bits from > the recorded voltages. Of course, that's a one-way data flow: > if you really want the microcontroller to participate, you > can't do it that way. What I think you want is very > difficult, and likely impractical.
That's one way. Given the tools we have, the only way that works. Amos, I am curious what you want to accomplish. Do you want a complete simulation of a system containining a microprocessor? If so, Spice, or anything Spice-like, is not for you. Do you want to simulate the analog portion of a circuit that connects to a pin on the micro? That's what John's approach will do. What are you using for a model of the micro? With our tools, the only one we have is John's approach. With some commercial products, an IBIS model might be the answer. > > > In the netlist there is a row starting for example with U3 > > but I don't know how to implement its behaviour in a way > > that the ngspice simulation considers it. I have seen in > > the gEDA Suite GUI that there is a row with written "Chip > > programs" that has leafs verilog .v files. May be that is > > the way? But in such a case how can I inform ngspice to use > > the verilog listing? Perhaps you want a digital Verilog simulator instead? How about Icarus Verilog? > Perhaps Al will chime in about gnucap: I suppose you could > write some sort of plugin that allows the program you'd run > in the microcontroller to interact in an event-driven way > with an analog sim. For now, it's the same as Spice. The plugin system is developed enough now to allow more people to get involved with development. I see plugins coming to do things like other languages, and other kinds of models. Eventually, I see plugins that will do things like Verilog-AMS behavioral models, interface to Icarus Verilog, interface to GHDL, interface to octave, IBIS, etc.. That's not ready yet. You could write a plugin to do something very specific, but it isn't practical yet. _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
