arduino

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In early 2017, I developed some interest in seven segment displays, and in how to drive them. Because of the large wealth of information surrounding the Arduino IDE on the internet, finding a program that could drive such a display proved to be a relatively easy task. Before long, on my breadboard I had a clock running using a four digit seven segment display. This was done using just one chip: the AtMega328p. To run a four digit seven segment display such as the one I have, a technique called multiplexing has to be used in order to control all of the display inputs, without an equal amount of microprocessor outputs. The code can be found here.

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Prior to this point, I had only a little experience with the PCB design software Eagle, I had designed and etched a couple simple boards based on the MC34063 switching regulator and a battery charger IC. Based on a recommendation from a friend, and also because the free version of Eagle is limited, I decided to try Kicad. To familiarize myself with it, I decided I’d design and etch a board for my seven segment display clock project. The process, once you’ve had a bit of practice and refined your technique can be quite quick. I also much prefer it to using per-board, although there are advantages to perf-board at times. The basic process I used is detailed here in this video.

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The final project turned out pretty well. Although there is no RTC (real time clock) the accuracy is pretty good, and doesn’t seem to really stray significantly. There is also a button which will demonstrate the multiplexing function by slowing it down, and gradually speeding it up until it reaches maximum speed. In person the display looks a bit nicer, but a screen cover to diminish the bleeding effect of the segments into those that are unlit might help a little. It was a fun project, and I recommend if you are interested in these displays to try it out!