Featuring an Arduino Nano microcontroller board and the keyboard from a small numeric keypad the LCD display the calculator is powered by a set of AA batteries through a DC-to-DC converter.

The chip gets programmed in an Arduino Uno and then transplanted into the calculator, a neat trick if you don’t have a dedicated programmer handy.

Assume that you are moving towards a complex microcontroller project bundled with blinkers, beepers, and a display panel. To link a standard 16×2 LCD directly with the microcontroller, for instance ...