skarg
63 lines
2.4 KiB
C
63 lines
2.4 KiB
C
/**************************************************************************
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*
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* Copyright (C) 2007 Steve Karg <skarg@users.sourceforge.net>
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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*********************************************************************/
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#include "hardware.h"
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/* Prescaling: 1, 8, 64, 256, 1024 */
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#define TIMER_1_PRESCALER 1
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/* Count: Timer counts up to 0xFFFF and then signals overflow */
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#define TIMER_1_TICKS (FREQ_CPU/TIMER_1_PRESCALER/1000)
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#define TIMER_1_COUNT (0xFFFF-TIMER_1_TICKS)
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/* Global variable millisecond timer - used by main.c for timers task */
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volatile uint8_t Timer_Milliseconds = 0;
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/* Configure the Timer */
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void timer_initialize(void)
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{
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/* Normal Operation */
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TCCR1A = 0;
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/* CS10 = clkI/O/1 (No prescaling) */
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TCCR1B = _BV(CS10);
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/* Clear any TOV1 Flag set when the timer overflowed */
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BIT_CLEAR(TIFR1,TOV1);
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/* Initial value */
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TCNT1 = TIMER_1_COUNT;
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/* Enable the overflow interrupt */
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BIT_SET(TIMSK1,TOIE1);
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/* Clear the Power Reduction Timer/Counter0 */
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BIT_CLEAR(PRR,PRTIM1);
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}
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/* Timer Overflowed! Increment the time. */
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ISR(TIMER1_OVF_vect)
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{
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/* Set the counter for the next interrupt */
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TCNT1 = TIMER_1_COUNT;
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/* Overflow Flag is automatically cleared */
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if (Timer_Milliseconds < 0xFF)
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Timer_Milliseconds++;
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}
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