title: Casio calculator key press event in MicroPython
body: <p>Is there a way to use a Casio calculator, like 'fx-CG50', that accepts python to listen to pressed keys?</p>
  <p>Currently the only way to use user input that I found was the console input. Is there another way?
  Casio does not provide any documentation at all. The used libraries like 'casioplot' do not help handling input.</p>
  <p>Maybe there is a native way in MicroPython I don't know of, since it runs on the chip itself.</p>