EmbeddedSystems/EmbeddedSystemsTHM/rotaryEncoder.c

/*
 * rotaryEncoder.c
 *
 * Created: 16/12/2021 16:34:05
 *  Author: n0x
 */ 

#include "rotaryEncoder.h"

#define ROTA PORTC7			/* define Rotary Encoder Button A */
#define ROTB PORTC6			/* define Rotary Encoder Button B */
#define ROTBUTTON PORTC5

/* enums */
enum{
	LEFT1, LEFT2, LEFT3, RIGHT1, RIGHT2, RIGHT3,
	INIT, WAIT
	} RotaryState = INIT; /* Enum for the rotary enc */

int16_t count;

void 
drehgeber_init(void)
{
	DDRC &= ~(7<<DDC5);			/* Set bit 5-7 of Data Direction Register C as input */
	PORTC |= (7<<PORTC5);		/* Initialize bit 5-7 of PORTC as for pull up resistor */
		
	/* With external interrupt */
	PCICR |= (1<<PCIE2);
	PCMSK2 |= (1<<PCINT23)|(1<<PCINT22);
}

ISR(PCINT2_vect)
{
	drehgeber_process();
}

void 
drehgeber_process(void)
{	
	/* calculate the value of Button A and B of rotary encoder */
	uint8_t a, b, enc;
	a = ((PINC & (1<<ROTA)) == 0);
	b = ((PINC & (1<<ROTB)) == 0)<<1;
	enc = a+b;
	
	switch(RotaryState)
	{
		case INIT:
			RotaryState = WAIT;
			break;
		
		case WAIT:
			if(enc == 1)
			{
				RotaryState = LEFT1;
			}
			if(enc == 2)
			{
				RotaryState = RIGHT1;
			}
			break;
		
		case LEFT1:
			if(enc == 3)
			{
				RotaryState = LEFT2;
			}
			if(enc == 0)
			{
				RotaryState = WAIT;
			}
			break;
		
		case LEFT2:
			if(enc == 2)
			{
				RotaryState = LEFT3;
			}
			if(enc == 1)
			{
				RotaryState = LEFT1;
			}
			break;
		
		case LEFT3:
			if(enc == 0)
			{
				/* Increment counter and wait */
				count++;
				RotaryState = WAIT;
			}
			if(enc == 3)
			{
				RotaryState = LEFT2;
			}
			break;
		
		case RIGHT1:
			if(enc == 3)
			{
				RotaryState = RIGHT2;
			}
			if(enc == 0)
			{
				RotaryState = WAIT;
			}
			break;
				
		case RIGHT2:
			if(enc == 1)
			{
				RotaryState = RIGHT3;
			}
			if(enc == 2)
			{
				RotaryState = RIGHT1;
			}
			break;
		
				
		case RIGHT3:
			if(enc == 0)
			{
				/* Decrement counter and wait */
				count--;
				RotaryState = WAIT;
			}
			if(enc == 3)
			{
				RotaryState = RIGHT2;
			}
			break;
	}
}

int16_t drehgeber_get(void)
{
	return count;
}