Decide on which programming language you will use to develop your circuit software with. For simple Web-based electronic circuit software, consider using JavaScript. For educational electronic software, consider using Flash Actionscript. Consider the C language if your circuit software will need to simulate electronic circuits with a high number of electronic components.
Define the type of electronic circuit components that you want to include in a circuit simulation. These may include resistors, capacitors, diodes and other electronic components. They may even include advanced electronic functions, such as microprocessors, waveform generators and operational amplifiers.
Define the types of input stimulus you will use in the circuit software. Consider batteries, analog waveforms, digital waveforms and current sources.
Define what type of electronic measurements that your circuit software will calculate. Consider the current through a resistor or the voltage across a resistor.
Define the different ways that the circuit components can be connected within your circuit software. Start with fixed circuit arrangements such as a simple series resistance circuit or a parallel resistance circuit. Also consider how to implement the circuit software so that a designer could construct and simulate the designs. Consider how you will have to change the computer code to accommodate arbitrary designs that a designer might create.
Devise the mathematical formula for the different electronic circuits in the previous step. For each possible output measurement, define the mathematical equation in terms of the input stimulus, such as the battery, and the components in the circuit, such as the resistor.
Determine the graphical interface method that will allow the designer to set and change the value of the electronic components. Construct the interface such that designer can select a component with a mouse. Consider letting the designer enter the selected component's value in a textbox, moving a slider bar or selecting a value from a list box.
Determine the method that will allow the designer to measure different electronic parameters. Devise a method that will allow the designer to select a component so that when selected the current through the component will be calculated and displayed. Also devise a method that will allow the designer to select a component and measure the voltage across it. Consider the use of the mouse and a key for the measurement selection process.
Write the programming code in modules; that is, code for the graphical user interface, code for the component models, code for the input stimulus, and code that calculates current and voltage values through and across each component in the circuit design.