You can turn a single analog pin on a microcontroller to a 4-bit input with 1-bit output with only some resistors, push button switches, an LED and a single JFET… It has been done forever… ...

Figure 3 Complete voltage inverter: 100 kHz pump clock (set by R1C1), Schmidt trigger and driver (U1), and commutator (U2). A 100 kHz pump clock is output on pin 2 of 74AC14 Schmidt trigger U1. This ...