Project Overview
The purpose of this project is to use seven segment displays and make circuits to display our date of birth. We use MultiSim and Tinker cad to do this. For this project we used a common Cathode display which means that the seven segment display will be connected to ground. The K-mapping was three variable K-mapping. The resistors had to be 180ohms on tinker cad and 10 ohms on multisim to see the display better.
Truth Table
The purpose of the truth table is to show what the output will be when you put in different inputs to get your date of birth. The A-G segments tell you what part of the seven segment display will be lit when XY and Z are switched on or off. The seven columns are like seven different truth tables, they show the output of each segment with all the different possible inputs. The X’s are there as space fillers, we don’t care about them, they can be on or off.
K-Maps & Simplified Logic Expression for the Seven Segments
K-Mapping is another way to get to a simplified logic expression using tables and grouping. In this case we are using 3 variable K-maps, first you look at the column of outputs in the truth table, there should be 8 outputs, you are going to make a 2x3 table for the k-mapping. and the first 2 variables go on the side and the last variable goes on top. Then you make all the possible outcomes for each variable. Then you try to find the biggest group possible of 1s in certain ways, it can be a 2x2 or a 1x2 or packman which goes off the table and circles around. Then you take the most simplified expression and that's your expression. The expressions are in sum of product form. To get to each midterm you group the 1s in certain ways like 2x2 or 1x2 or packman. We used K-mapping instead of Boolean algebra because it is easier to get 7 little expressions for each of the seven segments. We have so many expressions because of the seven segments that you need to make the display work.
MultiSim
2 inverter gates are needed, 3 nand gates, and 2 nor gates. This circuit would require 3 chips in total. We use NAND and NOR gates because they are universal and can be used to make any circuit. The NAND and NOR did not contain fewer gates. For one of the expression in AOI i would only need one gate but with NAND i needed 3 gates. Using nand and nor contains more chips than all AOI, AOI needs 2 chips and using NAND and NOR you need 3. This is important because less chips means less money to spend on chips. Seven segment displays are displays with seven wires that are connected to it and when certain switches are turned on a certain part of the SSD lights up. We use common cathode for our circuit. The resistors are used to adjust the brightness of the display. Usually, the resistors are kept at 180 ohms.
Tinkercad
At this stage, all the basic connections are made, everything is connected to power and/or ground, we are ready to put in the wires that will go through the chips.
At this stage, wires are being connected to chips and things are starting to come together and the SSD is started to be connected to.
Here, everything is complete and the circuit is working and will show my date of birth.
My second breadboarding experience was better than the first because I knew more about the components and how to wire them. I had to troubleshoot with Mrs. Zienty because of the NAND and NOR gates were kind of confusing. A mistake I made was forgetting to add more gates for the NAND segment of my circuit, I only put in one part of the NAND segment. The NAND and NOR gates had flipped inputs and outputs which were different than AOI chips. AOI pins went, Input A, Input B than output, but NAND and NOR were output, input, input.
Bill of Materials
1 NAND chip, 1 NOR chip, 1 Inverter chip, 2 switches, 4 resistors set to 180 ohms, 1 seven segment display, lots of wires.2 grounds, 1 power supplies.
Conclusion
I learned how to use NAND and NOR gates on tinkercad. I learned how to use Seven segment displays. One thing I would do differently next time is I wouldn't just use one gate for NAND by accident. I don't have any questions about the concepts.