The Five-Minute Schematic and Simulation

1. Overview

What's in this section? 

Here we will walk you through creating a new circuit diagram in LogicWorks. If you have a copy of the LogicWorks text book, it might be useful to refer to the tutorial in Chapter 4. Our tutorial is based on the one found in that chapter.

2. The Five-Minute Schematic and Simulation

1. Setup 

1.1 Open LogicWorks

1.2 Select "Create a new circuit diagram"

2. Placing Devices 

2.1 Locate the Parts Pallete. Inside it, you will find the Part Name Filter. This filter can be used to find any part included in the LogicWorks libraries

2.2 Use the Part Name Filter to find part "74_164". Double-click the part name in the Pallete, and place it in the editing area. Press the spacebar to return to Point mode. In Point mode, you can click and drag parts to move them around.

2.3 Clear the text in the filter, and now find the part labeled "XNOR-2". Place an XNOR-2 device to the right of the 74_164 so that the two inputs for the XNOR-2 are aligned with the top two outputs of the 74_164, QH and QG.

3. Connecting Devices 

3.1 Connect the output of the XNOR-2 to the B input on the 74_164. You can do this by clicking and dragging the end of the pin up and to the left.

3.2 Click and drag the A input of the 74_164 to meet the signal line that you just created.

Note: A dot should mark the intersection of these two lines.

4. Driving Devices 

4.1 Use the Part Filter to find a Binary Switch, and connect it to the CLR input of the 74_164.

Important: Hold Shift before you click on the Binary Switch. Clicking without holding Shift will cause you to interact with the device instead of selecting it to be moved.

4.2 Use the Part Filter to find a Clock device, and connect it to the CLK input of the 74_164.

5. Using the Timing Diagram 

5.1 To display the value of a signal line on the timing diagram, the line must be named. To name a line, select the Text Tool and click the line.

5.2 Using the Text Tool, name three things: the Clock line, the Feedback line from the XNOR-2, and the two inputs for the XNOR-2.

6. Probing Values 

6.1 A Binary Probe can be used to show the numerical value on a signal line.

6.2 Find a Binary Probe and connect it to the QA output from the 74_164.

7. Setting Device Parameters 

7.1 You can change the way a device works by setting its parameters.

7.2 Select the XNOR-2 device, and then select the "Simulation Params" from the Simulation menu.

7.3 Change the propagation delay for the XNOR-2 device to 5 ns.

Note: Changing the propagation delay alters the delay between changes on the clock line and changes on the feedback line.