Help Understanding Simulation Errors - Page 1
Forum section: electronics / general

author: Natustell
author_rank: Newbie
timestamp: February 06, 2023, 06:29:44 pm
content: I'm new to KiCad and I'm using it for work. I built my circuit with SPICE models (or so I think) and I am being bombarded with a litany of errors the moment the simulation starts. I have used LTSpice before, but it was much "plug and play". I followed a beginner tutorial to help me create my circuit.Note: No compatibility mode selected!warning, can't find model '<no_net>' from linera? <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> 0 <no_net> /v_cs_n /v_cs_p_s /v_cs_p_s /v_vs_c /v_vs_c <no_net> <no_net> <no_net> unconnected-_m_sw-pad2_ <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> 40Circuit: KiCad schematicError on line 11 or its substitute:ra? <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> 0 <no_net> /v_cs_n /v_cs_p_s /v_cs_p_s /v_vs_c /v_vs_c <no_net> <no_net> <no_net> unconnected-_m_sw-pad2_ <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> <no_net> 40unknown parameter (<no_net>)Background thread stopped with timeout = 0Error: circuit not parsed.I researched this as much as possible, and I have no idea what anything here means. "Error on line 11 or its substitute:" is especially confusing because I never wrote or saw and code directly.I wish I could share the sketch, but I am not the owner. I can give abstracted descriptions of it as neccessary and that's it. I had to change the name of the sketch to "KiCad schematic" after I read the error message so you can imagine how little information I can give.Somethings I will say initially:It's purpose is to send a current pulse to a device many times and measure the resistance across it over time.It contains a microcontroller that is simulated as just a resistor.It contains a spice MNMOS which is toggled by the microcontroller in reality and is modeled as a pulsed voltage source in the simulationIt contains a voltage source to model a power supply that must be shielded from varying load by an RC filter.

author: Natustell
author_rank: Newbie
timestamp: February 07, 2023, 11:34:36 pm
content: I gave up on trying to find a LIB file for the generic transistor that supposedly exists. I just found a random transistor that roughly appropriate. Now I need to deal with the errors caused by the unconnected pads of the Arduino.I need to include an Arduino UNO R3 in my sketch to keep track of which terminals are which. I don't want to actually simulate the Arduino for obvious reasons. It's purpose is only to read voltages and send a control signal. I need to probe the voltages on the analog input pins during the simulation to ensure I won't fry it. The control signal is sent by a VPULSE on the output of a digital pin for simulation purposes.I thought it would quick and simple to use the built-in Arduino_UNO_R3 symbol, then assign a resistor SPICE model to it of 40 ohms or whatever. Alternatively, I would need to make a resistor to act as each pin, which would be a pain.Is there no way for KiCAD to simulate the Arduino as a simple multi-terminal resistor?

author: LazyJack
author_rank: Frequent Contributor
timestamp: February 08, 2023, 11:51:39 am
content: Put resistor there. You are not really supposed to use the same schematic for simulation and design of the physical product. Spice simulation if for validating the core design. Then use real components with footprints etc. to get to the final result.

author: Natustell
author_rank: Newbie
timestamp: February 08, 2023, 07:58:16 pm
content: Using specific models of transistors has made designing my circuit a nightmare now. I need simple ideal P- and N-type MOSFET SPICE models for a prototype circuit. Specific models are not important at this stage. KiCAD has ideal models for resistors and capacitors built-in, but, surprisingly, none for MOSFETS.I am searching far and wide for some and I have found nothing.

author: Benta
author_rank: Super Contributor
timestamp: February 08, 2023, 08:29:37 pm
content: Quote from: Natustell on February 08, 2023, 07:58:16 pmI'm not surprised.None exist, there is no such thing as an "ideal MOSFET". Neither in Spice, nor anywhere else.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: February 14, 2023, 12:29:19 am
content: Why would you want an ideal fet?It seems much more useful to have a fet with some "average" properties (Whether you want a switching power fet, small signal fet or, power fet for "linear" applications. Then at least you have a starting point for getting an idea of which (non ideal) property is dominant in your simulation so you have something to optimize..