encoder.c

/*
	Copyright 2012-2015 Benjamin Vedder	benjamin@vedder.se

	This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
    */

/*
 * encoder.c
 *
 *  Created on: 7 mar 2015
 *      Author: benjamin
 */

#include "encoder.h"
#include "ch.h"
#include "hal.h"
#include "stm32f4xx_conf.h"
#include "hw.h"

// Private variables
static bool index_found;
static uint32_t enc_counts = 10000;

void encoder_init(uint32_t counts) {
	EXTI_InitTypeDef   EXTI_InitStructure;
	NVIC_InitTypeDef   NVIC_InitStructure;

	// Initialize variables
	index_found = false;
	enc_counts = counts;

	palSetPadMode(HW_HALL_ENC_GPIO1, HW_HALL_ENC_PIN1,
			PAL_MODE_ALTERNATE(HW_ENC_TIM_AF) |
			PAL_STM32_OSPEED_HIGHEST |
			PAL_STM32_PUDR_FLOATING);

	palSetPadMode(HW_HALL_ENC_GPIO2, HW_HALL_ENC_PIN2,
			PAL_MODE_ALTERNATE(HW_ENC_TIM_AF) |
			PAL_STM32_OSPEED_HIGHEST |
			PAL_STM32_PUDR_FLOATING);

	// Enable timer clock
	HW_ENC_TIM_CLK_EN();

	// Enable SYSCFG clock
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);

	TIM_EncoderInterfaceConfig (HW_ENC_TIM, TIM_EncoderMode_TI12,
			TIM_ICPolarity_Rising,
			TIM_ICPolarity_Rising);
	TIM_SetAutoreload(HW_ENC_TIM, enc_counts - 1);

	TIM_Cmd (HW_ENC_TIM, ENABLE);

	// Interrupt on index pulse

	// Connect EXTI Line to pin
	SYSCFG_EXTILineConfig(HW_ENC_EXTI_PORTSRC, HW_ENC_EXTI_PINSRC);

	// Configure EXTI Line
	EXTI_InitStructure.EXTI_Line = HW_ENC_EXTI_LINE;
	EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
	EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;
	EXTI_InitStructure.EXTI_LineCmd = ENABLE;
	EXTI_Init(&EXTI_InitStructure);

	// Enable and set EXTI Line Interrupt to the highest priority
	NVIC_InitStructure.NVIC_IRQChannel = HW_ENC_EXTI_CH;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x00;
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x00;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
	NVIC_Init(&NVIC_InitStructure);
}

float encoder_read_deg(void) {
	return ((float)HW_ENC_TIM->CNT * 360.0) / (float)enc_counts;
}

/**
 * Reset the encoder counter. Should be called from the index interrupt.
 */
void encoder_reset(void) {
	HW_ENC_TIM->CNT = 0;
	index_found = true;
}

/**
 * Set the number of encoder counts.
 *
 * @param counts
 * The number of encoder counts
 */
void encoder_set_counts(uint32_t counts) {
	if (counts != enc_counts) {
		enc_counts = counts;
		TIM_SetAutoreload(HW_ENC_TIM, enc_counts - 1);
		index_found = false;
	}
}

/**
 * Check if the index pulse is found.
 *
 * @return
 * True if the index is found, false otherwise.
 */
bool encoder_index_found(void) {
	return index_found;
}