Datos Curiosos: Circuit Maker
In this course, we will be using the free student edition of a commercial program, CircuitMaker, to design and simulate logic circuits. You can also get a copy of the student version of CircuitMaker from my office using this link: Download CircuitMaker from my office. Note that this software is avaialbe only forstudent use on their own computers; it is not available for use on college computers. The file you download (3,400,151 bytes) is a self-installing package for Windows; just click on it to start the installation process. Let me know if you do not have access to a computer on which you can install this software.
Using the Program
The program is very well designed, but it is not something that you canjust pick up and start using without some instruction. That's because it assumes you already know how to design digital logic, and does not provide real tutorial material.
What follows are some pointers to help you get started and to help you avoid some common problems. There is also help that comes with the program, but it tends to be sketchy.
1. The first thing to realize is thatCircuitMaster can be used to design and simulate both analog and digital signals. (Wherever you see "Spice" in the help system, it's talking about analog simulation.) You can build your circuit with out concern for this fact, but when you simulate it (run it), you must be sure to do so in digital mode. If you don't, you'll get a cryptic message, probably telling you that you need a ground node "before avalid spice netlist can be generated". To avoid this problem click on the toolbar button with the symbol for a transistor on it; it's exactly in the middle, 12 buttons in from both ends of the toolbar.
Just get in the habit of clicking on the transistor button (it turns into an AND gate) everytime you start running CircuitMaker.
If you get a message about "missing ground" when you try to simulateyour circuit, read the above paragraphs!
2. If you care about the neatness of your diagrams, select Grid under the Options menu, and select the "Snap to grid" option. I personally find it distracting to display the grid itself, but that's a choice you can make from the same menu.
3. Use the Devices menu to select gates, etc. to add to your circuit. Many simple gates and devices are listed onthe Hotkey submenu without the need to browse through device and parts lists. Use the Wire Tool (the toolbar button that looks like a plus sign) to connect inputs and outputs together.
4. A common input device is the digital logic switch, which alternates between outputting 0 or 1 each time you click on in. You can type a lower-case 's' to get one, or look for it in Hotkeys2 under the Devicesmenu, or select browse from the Devices menu, and select Digital -> Power.
5. The Hex Keypad device is very useful when you need to set several inputs at once. It has four outputs that you can control by typing a hex digit while the keypad is selected. Or click on it to make it step up by one.
6. You can simulate your circuit one step (propagation delay) at a time, or let it run at "fullspeed." EIther way, you can use the probe tool (the 8th button from the right end of the toolbar, next to the button that has an inverter on it) to look at the logic value of any part of your circuit. The probe will show H ("high"), L ("low"), or Z (indeterminate) as you make it hover over various parts of the circuit.
Better yet, turn on the trace option (under simulation options, or press F11).With this option on, the wires are colored to show their logic state and you don't need a probe.
7. You will want to look at the waveforms for various parts of the circuit as you run your simulations. Use F12 to turn this option on, or press the toolbar button to the right of the one with the inverter on it. The waveforms are displayed in a separate window, so select "tile" from the Window...