78 lines
1.7 KiB
C
78 lines
1.7 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 <stdint.h>
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#include "timer.h"
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volatile uint16_t timer_count = 0;
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// Configure timer 0 to generate a timer overflow interrupt every
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// 256*1024 clock cycles, or approx 61 Hz when using 16 MHz clock
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// This demonstrates how to use interrupts to implement a simple
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// inactivity timeout.
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void timer_init(void)
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{
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TCCR0A = 0x00;
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TCCR0B = 0x05;
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TIMSK0 = (1<<TOIE0);
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}
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inline
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void timer_clear(void)
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{
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uint8_t sreg = SREG;
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cli();
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timer_count = 0;
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SREG = sreg;
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}
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inline
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uint16_t timer_read(void)
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{
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uint16_t t;
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uint8_t sreg = SREG;
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cli();
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t = timer_count;
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SREG = sreg;
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return t;
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}
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inline
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uint16_t timer_elapsed(uint16_t last)
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{
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uint16_t t;
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uint8_t sreg = SREG;
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cli();
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t = timer_count;
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SREG = sreg;
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return TIMER_DIFF(t, last);
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}
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// This interrupt routine is run approx 61 times per second.
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// A very simple inactivity timeout is implemented, where we
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// will send a space character and print a message to the
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// hid_listen debug message window.
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ISR(TIMER0_OVF_vect)
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{
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timer_count++;
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}
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