54 lines
1.5 KiB
C
54 lines
1.5 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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#ifndef TIMER_H
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#define TIMER_H 1
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#include <stdint.h>
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#ifndef TIMER_PRESCALER
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# if F_CPU > 16000000
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# define TIMER_PRESCALER 256
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# elif F_CPU >= 4000000
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# define TIMER_PRESCALER 64
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# else
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# define TIMER_PRESCALER 8
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# endif
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#endif
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#define TIMER_RAW_FREQ (F_CPU/TIMER_PRESCALER)
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#define TIMER_RAW TCNT0
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#define TIMER_RAW_TOP (TIMER_RAW_FREQ/1000)
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#if (TIMER_RAW_TOP > 255)
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# error "Timer0 can't count 1ms at this clock freq. Use larger prescaler."
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#endif
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#define TIMER_DIFF(a, b, max) ((a) >= (b) ? (a) - (b) : (max) - (b) + (a))
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#define TIMER_DIFF_RAW(a, b) TIMER_DIFF(a, b, UINT8_MAX)
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#define TIMER_DIFF_MS(a, b) TIMER_DIFF(a, b, UINT16_MAX)
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extern volatile uint16_t timer_count;
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void timer_init(void);
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void timer_clear(void);
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uint16_t timer_read(void);
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uint16_t timer_elapsed(uint16_t last);
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#endif
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