“A calculator with 7 LEDs and a single button.
This implements a little calculator with 7 LEDs as output (applying a shift-register), a M5Stack-Atom-Lite as the MCU and its button as input.
Usage
Select the first number by cycling through digits 0 to 9, minus-sign “-” and decimal point “.” by short press. To enter another digit double-press. To finish the number and get to the operator selection apply a long press.
Cycle through the operators plus, minus, mult and div with a short-press and leave to the input of the second operand with a long press. Enter the second operand like the first one.
If you then long press to finish the number, the result will be displayed.”