steering_encoder.c

/*
 * steeringEncoder.c
 *
 * Created: 02.02.2016 22:40:47
 *  Author: Daniel
 */ 

#include "steeringEncoder.h"
#include <avr/io.h>
#include <avr/interrupt.h>
#include <stdbool.h>

#include "../../Data_transmission/data_transmission.h"
#include "../../ADC_drivers/can_messages.h"

#define ENCODER_A_PIN 5
#define ENCODER_B_PIN 0
#define ENCODER_Z_PIN 2

#define ENCODER_A_PORT PORTB
#define ENCODER_B_PORT PORTC
#define ENCODER_Z_PORT PORTB

#define ENCODER_A_INPUT PINB
#define ENCODER_B_INPUT PINC
#define ENCODER_Z_INPUT PINB

#define ENCODER_A (ENCODER_A_INPUT & (1 << ENCODER_A_PIN))
#define ENCODER_B (ENCODER_B_INPUT & (1 << ENCODER_B_PIN))


static uint8_t rot_state = 0;
static uint8_t prev_rot_state = 0;
static int16_t encoder_counter = 10;
static int16_t counter = 0;


/*
void handleSteeringPosition() {
	if (internal_counter[STEERING_RATE_INDEX] >= (20000/100)) {
		steering_pos_and_rate.can_data.i16[0] = getEncoderValue();
		if (can_send_message(&steering_pos_and_rate) == CAN_STATUS_COMPLETED)
		{
			cli();
			internal_counter[STEERING_RATE_INDEX] = 0;
			sei();
		}
	}
}*/




void encoder_init(){
	
	DDRB &= ~((1<<PORTB5)| (1<< PORTB2));				//Bitwise OR, set A, B, Z pins as input
	DDRC &= ~(1<<PORTC0);
	PORTB &= ~((1<<PORTB5)| (1<< PORTB2));				// disable pull ups and make it tristate.
	PORTC &= ~(1<< PORTC0);
	

	//Interupt pin init:
	EICRA |= (1 << ISC20);					
	EIMSK |= (1 << INT2);					//Read interupt on INT2
	EIFR  |=	(1 << INTF2);			// External Interrupt Flag Register
	
	//Interupt pin init:
	EICRA |= (1 << ISC30);					
	EIMSK |= (1 << INT3);					//Read interupt on INT3
	EIFR  |=	(1 << INTF3);			// External Interrupt Flag Register
	
}





bool xor(uint8_t a, uint8_t b){
	return (a || b) && (!(a && b));
}


ISR(INT2_vect){	//Pin A changed	
	cli();		
	if (!(xor(ENCODER_A, ENCODER_B))){				//If !(A ^ B), count down
		counter += 1;
	}
	else{						//else, count up
		counter -= 1;
	}
	sei();
}
ISR(INT3_vect){		//Pin B changed
	cli();
	if (!(xor(ENCODER_A, ENCODER_B))){				//If !(A ^ B), count down
		counter -= 1;
	}
	else{						//else, count up
		counter += 1;
	}
	sei();
}

int16_t getEncoderValue(void){
	return counter;
}

void encoderReset(void){
	counter = 0;
}

int16_t convert_to_degree(void){
	int16_t degree_from_setpoint = (counter*360*10)/4096;
	return degree_from_setpoint;
}

static int16_t previousCounterValue = 0;
int16_t getSteeringRate(void)
{
	
	int16_t rate;

	// Sends at 128Hz --> dt = 1/f = 1/128 ==> rate = delta_measurements * f
	// equivalent to bit shift left by seven signs.
	rate = (counter - previousCounterValue);
	
	// Output is the derivative of steering position, bit shifter right 7 times.
	// Upon retrieval, should be bit shifted left 7 times.
	return rate; 

}

steering_encoder.h

/*
 * steeringEncoder.h
 *
 * Created: 02.02.2016 22:41:03
 *  Author: Daniel
 */ 
#include <avr/io.h>
#include <stdbool.h>

#ifndef STEERINGENCODER_H_
#define STEERINGENCODER_H_


void encoder_init();
//void handleSteeringPosition();
int16_t getEncoderValue(void);
int16_t getSteeringRate(void);
void encoderReset(void);
int16_t convert_to_degree(void);



#endif /* STEERINGENCODER_H_ */