KY-040 rotary encoder giving double steps per detent

Projects Programming
1

Hi, I’m using a KY-040 rotary encoder with an Arduino and trying to get exactly one increment per physical detent

The behavior is inconsistent:

  • Sometimes 1 detent = 1 step (correct)
  • Sometimes 1 detent = 2 steps (extra trigger in the middle)
  • Sometimes it even needs 2 detents for 1 step

Here is my code:

int readRotary() {
    static int lastState = 0;
    static int8_t enc_states[] = {0,-1,1,0, 1,0,0,-1, -1,0,0,1, 0,1,-1,0};
    static int8_t accumulator = 0;

    int currentState = (digitalRead(clkPin) << 1) | digitalRead(dtPin);
    accumulator += enc_states[(lastState << 2) | currentState];
    lastState = currentState;

    if (accumulator >= 2) { accumulator = 0; return 1; }
    if (accumulator <= -2) { accumulator = 0; return -1; }
    return 0;
}

I want so that for every detent (click) there is, the function will produce only one 1 or -1

Also btw, no hardware debouncing, and I am using digitalRead() in loop

Thanks, I hope my question can be answered.

2

Hi, I asked ChatGPT and it gave back a solution that actually works! (for once)

int readRotary() {
    static int lastState = 0;
    static int8_t enc_states[] = {0,-1,1,0, 1,0,0,-1, -1,0,0,1, 0,1,-1,0};
    static int8_t accumulator = 0;

    int currentState = (digitalRead(clkPin) << 1) | digitalRead(dtPin);
    accumulator += enc_states[(lastState << 2) | currentState];
    lastState = currentState;

    if (accumulator >= 4) { accumulator = 0; return 1; }
    if (accumulator <= -4) { accumulator = 0; return -1; }
    return 0;
}

No need for anyone helping anymore, as this code works good. Feel free to use this code in your own projects.

3

I would also add a 0.1uF ceramic capacitor from clock to ground, and another from step to ground. This will help stabilise the lines from high frequency bouncing you get with any mechanical switch.

4

Are you sure your rotary’ encoder does not give 2 or 4 ticks per click - always ?

Try with the encoder library and see what it says.

5

i believe that encoder is designed to recognize just one input as a change and the other input as the direction ... per indent