STM32 – Подключаем энкодер

С детектора фронтов возьмем не инверсный, т.е. активный уровень высокий (для первого и второго входа):

TIM2->CCER = TIM_CCER_CC1P | TIM_CCER_CC2P;

// A/B/button bits
enum { ENC_A=1, ENC_B=2, ENC_AB=3, ENC_C=4 };

// events
enum { ENC_NONE, ENC_FORW, ENC_BACK, ENC_BUTT };

// AB counter reset threshold
#ifndef ENC_AB_RES
	#define ENC_AB_RES 300
#endif

// short press counter
#ifndef ENC_BUTT_SHORT
	#define ENC_BUTT_SHORT 80
#endif

// long press counter
#ifndef ENC_BUTT_LONG
	#define ENC_BUTT_LONG 2000
#endif

struct enc_struct {
	u8  en;                  // disable / enable

	// A/B input
	u8  prev, cur;           // previous/current state
	u8  inv, event;          // =1 direction inversion, current event
	s8  acc, threshold, dec; // step accumulator, threshold, decrement
	u16 cnt;                 // current state counter

	// button input
	struct {
		u8  prev, cur;       // previous/current state
		u16 cnt;             // current state counter
	} butt;
};

u8 enc_update( struct enc_struct *enc, u8 next );

#include "enc.h"

// forward/backward next states
const u8 enc_forw[] = { 0b01, 0b11, 0b00, 0b10 };
const u8 enc_back[] = { 0b10, 0b00, 0b11, 0b01 };

u8 enc_update( struct enc_struct *enc, u8 next ){
	enc->event = ENC_NONE;      // reset event

	// update AB state
	enc->prev  = enc->cur;      // update previous AB state
	enc->cur   = next & ENC_AB; // get current AB state
	if (enc->cur != enc->prev){ // changed ?
		enc->cnt = 0;
		// forward direction
		if (enc->cur == enc_forw[enc->prev]){
			if (enc->inv) enc->acc--; else enc->acc++;
		}
		// backward direction
		else if (enc->cur == enc_back[enc->prev]){
			if (enc->inv) enc->acc++; else enc->acc--;
		}
		// wrong sequence - reset accumulator
		else enc->acc = 0;

		// forward step
		if (enc->acc >= enc->threshold){
			enc->acc -= enc->dec;
			enc->event = ENC_FORW;
		}
		// backward step
		else if (enc->acc <= -enc->threshold){
			enc->acc += enc->dec;
			enc->event = ENC_BACK;
		}
	} else {
		// no change - increment counter
		if (enc->cnt != 0xFFFF) enc->cnt++;
		// reset accumulator
		if (enc->cnt == ENC_AB_RES) enc->acc = 0;
	}

	// update button state
	enc->butt.prev = enc->butt.cur;
	enc->butt.cur  = !(next & ENC_C);
	// button state change - reset counter
	if (enc->butt.cur != enc->butt.prev){
		enc->butt.cnt = 0;
	} else { // not changed - increment counter
		if (enc->butt.cnt != 0xFFFF) enc->butt.cnt++;
		// gnenerate button press event
		if ((enc->event == ENC_NONE) && enc->butt.cur && ((enc->butt.cnt == ENC_BUTT_SHORT)||(enc->butt.cnt == ENC_BUTT_LONG)))
			enc->event = ENC_BUTT;
	}

	return enc->event;
}