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/*
* spreadspace avr utils
*
*
* Copyright (C) 2021 Christian Pointner <equinox@spreadspace.org>
*
* This file is part of spreadspace avr utils.
*
* spreadspace avr utils 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
* any later version.
*
* spreadspace avr utils 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 spreadspace avr utils. If not, see <http://www.gnu.org/licenses/>.
*/
#include <avr/io.h>
#include <avr/interrupt.h>
#include "fan.h"
#define PWM_VAL_MAX 160
void fan_init(void)
{
// timer for tacho
DDRD &= ~(1<<PD4);
PORTD |= (1<<PD4);
TCCR1B = 0; // make sure timer is stopped
TCCR1A = 0;
TCNT1 = 0;
TIMSK1 = (1<<ICIE1);
TCCR1B = (1<<CS12); // start timer
// PWM for speed control
DDRB |= (1<<PB6);
TCCR4B = 0; // make sure timer is stopped
TCCR4A = (1<<COM4B1) | (1<<PWM4B);
TCCR4D = (1<<WGM40);
TCNT4 = 0;
OCR4C = PWM_VAL_MAX;
OCR4B = PWM_VAL_MAX/2; // set duty cycle to 50:50
TCCR4B = (1<<CS41); // start timer
}
#define TACHO_DATA_LEN 8
static uint16_t tacho_data[TACHO_DATA_LEN];
static uint8_t tacho_data_idx = 0;
static uint16_t tacho_last_ts = 0;
ISR(TIMER1_CAPT_vect)
{
uint16_t current = ICR1;
if(current > tacho_last_ts) {
tacho_data[tacho_data_idx] = current - tacho_last_ts;
} else {
tacho_data[tacho_data_idx] = (UINT16_MAX - tacho_last_ts) + current;
}
tacho_last_ts = current;
tacho_data_idx = (tacho_data_idx >= (TACHO_DATA_LEN-1)) ? 0 : tacho_data_idx+1;
}
uint16_t fan_get_rpm(void)
{
uint32_t sum = 0;
cli();
for(uint8_t i = 0; i < TACHO_DATA_LEN; i++) {
sum += tacho_data[i];
}
sei();
return (1875000 / (sum / TACHO_DATA_LEN));
}
void fan_speed_set(uint8_t val)
{
OCR4B = (val > PWM_VAL_MAX) ? PWM_VAL_MAX : val;
}
uint8_t fan_speed_get(void)
{
return OCR4B;
}
void fan_speed_inc(void)
{
if(OCR4B < PWM_VAL_MAX)
OCR4B++;
}
void fan_speed_dec(void)
{
if(OCR4B > 0)
OCR4B--;
}
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