HMSpice is an electronic circuit simulator for circuits containing voltage, current sources (independent/dependent) and resistors, i.e., for purely resistive circuits. This simulator is inspired by the "Circuit Simulation" book by Farid N. Najm. This work was part of my senior design project at the Department of Electrical Engineering, Shiv Nadar University, in the Monsoon 2022 semester.
- Working
- Installation and Running HMSpice
- Accepted Syntax of Circuit Elements
- UML Diagrams
- Constraints
- List of Errors and Warnings
- Credits
HMSpice uses Modified Nodal Analysis (MNA) to find all the nodal voltages and required currents across the branches. It builds the MNA and RHS matrices in O(n) time complexity. It goes through the netlist, checks for any error in the netlist, and makes the matrices, on the fly, in linear time, using the element stamp of each component.
The contribution of every element to the matrix equation is described by employing an element stamp template. Every element has different stamps based on their contribution to the matrices and on which group they belong to.
The simulator uses the Eigen library to implement the solver. We have used LU factorization to solve the equation.
- Requirement: GCC Compiler (or any other C++ compiler)
- Download the project from GitHub
- Compile all the files
- Type the netlist in the circuit.hms file
- Run the executable file from the terminal to get all nodal voltages and required currents
- Independent Current Source:
I<string> <node.+> <node.-> <value> [G2] - Dependent Current Source:
Ic<string> <node.+> <node.-> <factor> <variable> <circuitElement> - Independent Voltage Source:
V<string> <node.+> <node.-> <value> - Dependent Voltage Source:
Vc<string> <node.+> <node.-> <factor> <variable> <circuitElement> - Resistor:
R<string> <node.+> <node.-> <value> [G2]
G2, for group 2, is an optional field that tells the simulator that the user is interested in knowing the current across the circuit element. By default, all voltage sources are group 2.
Accepted values for variable are either V or I, which tell the simulator that the source is dependent on that particular variable of the circuitElement.
<node.+>, <node.-> takes string and value, factor takes value in normal integer, decimal or exponential form but doesn't allow multiplier.
This project contains one structure: CircuitElement, and three classes: Parser, Edge and Node. Following is the UML diagram of each.
- One of the nodes in the netlist must be 0 (string)
- Current controlling variable's element must be in group 2
- Controlling variable cannot be dependent on another dependent variable
- Values in the netlist cannot accept multipliers (give actual values or in exponential)
- Inline comments are best avoided (if required, explicitly state the group before commenting)
- Circuit element can't have a zero value or factor
- Unknown element
- Circuit must contain ground (0)
- Checks whether the controlling element is present in the netlist
- Controlled source cannot be cascaded
- Reviews for legal input value or factor
- Illegal controlling variable argument
- Netlist not available
- Checks and makes sure that the controlled element is in group 2 if the controlling variable is current
- Two nodes of a component cannot be the same (Omits the component)
- Mention the correct group (by default, assigns group 1)
I am thankful to the Eigen library team for developing and maintaining the library, because of which the matrix equation could be solved so efficiently.