From the outside, the pulse potentiometer has three pins like the ordinary potentiometer, but internally, two metal static plates of different lengths are connected with pins 1 and 2, and a metal moving plate with 12 or 24 teeth around pin 3. When the pulse potentiometer rotates, there are four states: pin 3 is connected with pin 1, and pin 3 is fully connected with pin 2 and pin 1; Pin 3 is connected to pin 2, and pin 3 is completely disconnected from pin 2 and pin 1.

Working principle of potentiometer

In practical use, pin 3 is generally grounded as the data input. Pins 1 and 2 are connected to the I / O port of the single chip microcomputer as data output terminals. As shown in Figure 2, connect pin 1 with P1 of MCU 0, pin 2 is connected with P1 1 connected. When the pulse potentiometer rotates left or right, P1 0 and P1 1 will periodically generate the indicated waveform. If the 12 point pulse potentiometer rotates once, 12 groups of such waveforms will be generated, and the 24 point pulse potentiometer will generate 24 groups of such waveforms; A set of waveforms (or a cycle) contains four working states. Therefore, as long as P1 is detected 0 and P1 1, you can identify whether the pulse potentiometer rotates left or right.