One of [Kale_3D]’s teachers had made an Arduino-powered calculator. It wasn’t robust and didn’t last too long in the classroom environment. After the non-functional calculator sat around the class for a while, [Kale_3D] decided he would give a shot at repairing it. Along the way the project didn’t just get repaired, it got a full rebuild.
This calculator uses a full 16 button matrix keypad. The Arduino deciphers button pushes with the help of the Keypad library, at which time the appropriate character is displayed on the 2×8 LCD screen. Selecting the function is a little different from normal since this project is limited to 16 buttons. Two of the buttons allow scrolling through not only standard arithmetic functions but trigonometric functions also. This was one of the features that the previous version was not capable of.
To protect the components, an enclosure was made out of 1/4″ laser cut wood. The pieces have notched edges to permit a nice fit. Even so, corner blocks were added to give the case even more rigidity.
Yes, this calculator is not practical, but that’s not the point. In the end [Kale_3D] felt that the project was definitely worth doing. He had learned a bunch of stuff about Arduino and especially code debugging! Most important of all he had a good time building it. There’s a video after the break showing how it works. The code and wiring diagrams are available for download on the project’s Instructable page.
Nice work!
Maybe fit an adjustable resistor to the LCD’s contrast pin?
Hmmm… with an access to laser cutter, I would cut holes for the keypad and display and sink them into the case for better protection.
How does he make the display fade like that? Contrast pin connected to DAC?
Very neat. Why is the case so deep? I have a hard time imagining what is going on in there that requires that much volume.
This is used in a teaching environment. More space makes it easy to regularly open it up, examine, probe, and modify.
Holy shit ,, that schematic .. gives me anxiety.
The telephone keypad upsets me… and it obviously wasn’t designed for right-handed people…
Am I the only one bothered by the mismatched screws?
Otherwise it looks like making one could be educational if you figure it out yourself rather than just copying.
You should have seen the look on my face when I saw this in my google now feed. I was just thinking Hey look its my calculator.