Changes

[[RF.Spice A/D]] allows you to view the state of your digital inputs and outputs graphically in real time using "'''Live Timing Diagrams'''". The digital timing diagram appears at the bottom of the Workshop just like a regular graph. However, these are interactive "live" graphs that change and expand with every time step. For this part of the lesson, you keep the value of "Time Step" at 20ns. First, reset your simulation engine by clicking the "'''Stop/Reset'''" [[File:b2Stop_Tool.png]] button of the [[Main toolbar|Main Toolbar]]. Also reset the values of all the three inputs to 0.

To activate the timing diagrams, click the "'''Show/Hide Live Digital Timing Diagrams'''" [[File:b2Timing_Tool.png]] button of the '''[[Schematic toolbar|Schematic Toolbar]]'''. Nothing happens immediately because you haven't started a [[Digital Simulation|digital simulation]] yet. Here is the game plan that you will follow next. You will set the values of each input to 1 sequentially, one at a time. You will increment three time steps between any two actions or events. Then, you will revert the values of the three inputs back to 0 sequentially, one at a time, in the reverse order, until all the three inputs are 0 again. The following table shows the timing of the events:

Start the [[Digital Simulation|digital simulation]] with all zero inputs and increment three time steps to 60ns. You will see that four timing diagrams appear at the bottom of the Workshop, one for each input and one for the output. In general every input and output port will have a timing diagram. Then, change the value of Input 1 to 1. Step again and you will see that the timing diagrams immediately get updated because the input states have now changed. Increment two more time steps to 120ns. Then, change the value of Input 2 to 1. Follow this recipe according to the above event table with 60ns intervals until all inputs are set to 0 again. The timing diagrams get updated after each change of state and the final diagrams are shown in the figure below. Note that your timing diagram may expand too long to fit into the bottom graph window. In that case, click on the title of the graph window tab to make it the active window. The toolbar changes accordingly. Then click the "'''Zoom Out Horizontal'''" [[File:b2ZoomOutHoriz_Tool.png]] button of the [[Graph toolbar|Graph Toolbar]] to shrink the diagram until it has the right size for viewing.

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