INDIVIDUAL ASSIGNMENT : As a final project in our digital engineering lab, we were assigned to design and create our own logic circuits using the knowledge we had gained in class. My project was a "solar energy harvesting stimulator" aimed at developing and improving students' creativity and understanding of logic circuits. The system was composed of only ordinary digital circuits such as 4-Bit Magnitude Comparators (7485) without using an MCU. The stimulator I designed can display the amount of energy harvested by the solar panel according to the influx of sunlight. It can also give an alarm to notify completion of the charge. To operate this circuit, a light-to-frequency converting chip was used as the clock source, as shown in (a). When light hits the chip in (a), a clock source is generated, and the ROM (read-only memory) unloads embedded data to display LEDs according to the embedded sequence. The sun-shaped LEDs roll and blink if there is an influx of sunlight, as shown in (b) and (c), and the speed of the rolling and blinking LEDs depends on the strength of the sunlight. (d) and (e) show the amount of charged energy. Battery-shaped LEDs turn on in order if the amount of harvested energy reaches 20%, 40%, 60%, 80%, and 100%. The FND shows the percentage of the charged energy with a resolution of 1%. When the harvesting is finished, a voice-recorded chip gives an alarm of "Charging is completed" from a speaker, as shown in (f). Overall, this project was an excellent opportunity to solidify and apply all the knowledge gained in the course and develop my skills in designing logic circuits.