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/* Setting Up Digital Circuit Simulations */
<b>Setting the Input</b>
The simplest input device for digital circuits is the "Digital Input" with the keyboard shortcut N. For the basic input port, click on the up and down arrows with the selection arrow to toggle its value between 0 and 1. Or double click on the input port to open the device's property dialog and set or change the input's value. [[B2RF.Spice A/D]] offers a number of other input devices for [[Digital Simulation|digital simulation]]. With the "Toggle Switch", click on the switch to change its value. The button changes with each click of the mouse. The "DIP8 Switch" has eight output pins, each of which are controlled by a separate switch. Clicking on the switches will toggle their output values. With the hexadecimal "Keypad", click on one of the 16 buttons to select a value from 0, 1, ..., 9, A, B, ..., F. A "Digital Source" allows you to define a sequence of binary values as a function of time (or time step index).
[[File:B2TUT4 1.png|thumb|400px| A simple digital circuit with three digital inputs and one digital output.]]
Set up the input values and set the time step you desire from the Simulation Time Options dialog. To open this dialog, click the Step Interval Settings [[File:b2Interval_Tool.png]] button on the [[Main toolbar|Main Toolbar]], or select the Time Options item of the Simulate Menu, or use the keyboard shortcut Ctrl+I. A typical time step for digital circuit simulations is 20ns. Click the Step [[File:b2Step_Tool.png]] button to start the simulation. The simulation time is incremented by one time step. The current time is displayed in the simulation toolbar next to the control buttons. You can view the logical state of the wires and device pint either using the logic Probe Tool or by Circuit [[Animation]]. The values of input and output devices are displayed, too. You can change the values of input devices in real time. Click the Step [[File:b2Step_Tool.png]] button once again to increment the time by another time step. The Walk button starts the simulation but increases the simulation time by the walk factor, which can be set in the Simulation > Time Options menu. Click the Strop/Reset [[File:b2Stop_Tool.png]] button to reset the time to t = 0.
With [[B2RF.Spice A/D]] you can also view live digital timing diagrams during a live [[Digital Simulation|digital simulation]]. Click on the "Show/Hide Live Digital Timing Diagram" [[File:b2Timing_Tool.png]] button in the [[Schematic toolbar|Schematic Toolbar]]. Initially nothing happens. A soon as the [[Digital Simulation|digital simulation]] starts, a graph window opens up at the bottom of the screen that shows live timing diagrams for all the input and output devices. As you continue to step the time, these graphs expand. Similar to other graphs, the digital timing diagrams have their own settings dialogs in the Toolbox. Note that the timing diagrams are updated only when a change occurs in your circuit.
[[File:B2TUT4_13.png|thumb|center|600px| Live digital timing diagram during a live digital simulation.]]
