Push button rotary encoders are popular input devices for making simple user interfaces. Using a pushbutton rotary encoder requires 3 input pins on your microcontroller: 1 for the switch and 2 for the quadrature outputs. However, in a recent application I had only 1 pin remaining on my MSP430G2553. My only choice was to leverage that pin's analog input capabilities. I first sketched out my requirements, then designed a circuit, measured the performance of my design and wrote microcontroller software to realize it.