Engineering Portfolio
Birthdate Display
Introduction Paragraph:
The final assignment for first semester was to build a circuit that displayed my birthdate.
I built a circuit with a 555 timer that connected to d flip-flops which then connected to AOI logic chips which connected to a seven segment display which displayed the numbers.
I had used my original 555 timer and d flip-flop set up that I had made for a previous project.
There are also two switches, the one taped to the board resets and stops the timer and lights, while the other one pauses the timer (and lights).
Video of the Working Circuit with Text Explanation:
1. The power is brought into the board, where it is first sent to the 555 timer, where a light is attached, flashing to indicate the timer is working properly.
2. From the timer, the power is directed to 3 d flip-flops, which slows the power coming from the timer. Each light, from red to yellow to green, proves that the power coming through is slowing down. Each one acts like a binary counter.
3. From there, each d flip-flop was labeled as X, Y, or Z, based on speed. Using calculations as pictured below in the next section, each variable of power was sent to the appropriate inverting, or, or and chips.
4. After the proper configuring of 0 or 1 (or power positive or negative) the power is brought to the 7 segment display, which outputs the display:
07-20-05
Truth tables and K-Maps:
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Top: I first figured out when each light should be on or off for each number to be displayed.
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K-Maps: I made k-maps to determine the simplest forms of the equation for each light, which is labeled a-g.
Bottom Left: I wrote down each equation per letter/light and found where patterns repeat, with multiplying and adding. I color-coded it too, so it would be easier to decipher. I also used the color codes in my Multisim and on notes that are on tape on my physical build.
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Middle Right: I counted the number of chips I would have to use and how many times a chip could be used.
Circuit Design Considerations:
I ended up using 1 invert, 3 ands, and 3 ors. I found it much more direct and easier to use these chips rather than nands or nors. I also think it would use the least amount of chips, even if I am using more types. Additionally, I was able to reuse some of the outputs so I didn’t have to repeat the “math” and use unnecessary chips.
Reflection:
Overall, I enjoyed making the project. I know that I understand the concepts much better and making it a second time would go a lot faster. I still think building it with the chips I used was best and was the simplest for me to understand and troubleshoot. The only thing I would change is using one less d flip-flop because it would lead to one less chip being used.