134 lines
3 KiB
C
134 lines
3 KiB
C
/*
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Copyright 2011 Jun Wako <wakojun@gmail.com>
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include <util/atomic.h>
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#include <stdint.h>
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#include "timer_avr.h"
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#include "timer.h"
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// counter resolution 1ms
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// NOTE: union { uint32_t timer32; struct { uint16_t dummy; uint16_t timer16; }}
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volatile uint32_t timer_count;
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/** \brief timer initialization
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*
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* FIXME: needs doc
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*/
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void timer_init(void) {
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#if TIMER_PRESCALER == 1
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uint8_t prescaler = _BV(CS00);
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#elif TIMER_PRESCALER == 8
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uint8_t prescaler = _BV(CS01);
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#elif TIMER_PRESCALER == 64
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uint8_t prescaler = _BV(CS00) | _BV(CS01);
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#elif TIMER_PRESCALER == 256
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uint8_t prescaler = _BV(CS02);
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#elif TIMER_PRESCALER == 1024
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uint8_t prescaler = _BV(CS00) | _BV(CS02);
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#else
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# error "Timer prescaler value is not valid"
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#endif
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#if defined(__AVR_ATmega32A__)
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// Timer0 CTC mode
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TCCR0 = _BV(WGM01) | prescaler;
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OCR0 = TIMER_RAW_TOP;
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TIMSK = _BV(OCIE0);
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#elif defined(__AVR_ATtiny85__)
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// Timer0 CTC mode
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TCCR0A = _BV(WGM01);
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TCCR0B = prescaler;
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OCR0A = TIMER_RAW_TOP;
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TIMSK = _BV(OCIE0A);
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#else
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// Timer0 CTC mode
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TCCR0A = _BV(WGM01);
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TCCR0B = prescaler;
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OCR0A = TIMER_RAW_TOP;
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TIMSK0 = _BV(OCIE0A);
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#endif
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}
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/** \brief timer clear
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*
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* FIXME: needs doc
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*/
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inline void timer_clear(void) {
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ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { timer_count = 0; }
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}
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/** \brief timer read
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*
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* FIXME: needs doc
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*/
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inline uint16_t timer_read(void) {
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uint32_t t;
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ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { t = timer_count; }
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return (t & 0xFFFF);
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}
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/** \brief timer read32
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*
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* FIXME: needs doc
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*/
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inline uint32_t timer_read32(void) {
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uint32_t t;
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ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { t = timer_count; }
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return t;
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}
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/** \brief timer elapsed
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*
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* FIXME: needs doc
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*/
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inline uint16_t timer_elapsed(uint16_t last) {
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uint32_t t;
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ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { t = timer_count; }
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return TIMER_DIFF_16((t & 0xFFFF), last);
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}
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/** \brief timer elapsed32
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*
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* FIXME: needs doc
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*/
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inline uint32_t timer_elapsed32(uint32_t last) {
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uint32_t t;
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ATOMIC_BLOCK(ATOMIC_RESTORESTATE) { t = timer_count; }
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return TIMER_DIFF_32(t, last);
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}
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// excecuted once per 1ms.(excess for just timer count?)
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#ifndef __AVR_ATmega32A__
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# define TIMER_INTERRUPT_VECTOR TIMER0_COMPA_vect
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#else
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# define TIMER_INTERRUPT_VECTOR TIMER0_COMP_vect
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#endif
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ISR(TIMER_INTERRUPT_VECTOR, ISR_NOBLOCK) { timer_count++; }
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