mirror of
https://github.com/stargieg/bacnet-stack
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107 lines
3.3 KiB
C
107 lines
3.3 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 <stdint.h>
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#include "hardware.h"
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/* This module is a 1 millisecond timer */
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/* Prescaling: 1, 8, 64, 256, 1024 */
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#define TIMER_PRESCALER 64
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/* Count: Timer0 counts up to 0xFF and then signals overflow */
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#define TIMER_TICKS (F_CPU/TIMER_PRESCALER/1000)
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#if (TIMER_TICKS > 0xFF)
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#error Timer Prescaler value is too small
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#endif
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#define TIMER_COUNT (0xFF-TIMER_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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/* MS/TP Silence Timer */
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static volatile uint16_t SilenceTime;
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/* Configure the Timer */
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void Timer_Initialize(
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void)
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{
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/* Normal Operation */
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TCCR1A = 0;
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/* CSn2 CSn1 CSn0 Description
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---- ---- ---- -----------
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0 0 0 No Clock Source
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0 0 1 No prescaling
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0 1 0 CLKio/8
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0 1 1 CLKio/64
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1 0 0 CLKio/256
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1 0 1 CLKio/1024
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1 1 0 Falling Edge of T0 (external)
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1 1 1 Rising Edge of T0 (external)
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*/
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TCCR0B = _BV(CS01) | _BV(CS00);
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/* Clear any TOV1 Flag set when the timer overflowed */
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BIT_CLEAR(TIFR0, TOV0);
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/* Initial value */
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TCNT0 = TIMER_COUNT;
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/* Enable the overflow interrupt */
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BIT_SET(TIMSK0, TOIE0);
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/* Clear the Power Reduction Timer/Counter0 */
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BIT_CLEAR(PRR, PRTIM0);
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}
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/* Timer interupt */
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/* note: Global interupts must be enabled - sei() */
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/* Timer Overflowed! Increment the time. */
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ISR(TIMER0_OVF_vect)
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{
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/* Set the counter for the next interrupt */
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TCNT0 = TIMER_COUNT;
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/* Overflow Flag is automatically cleared */
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/* Update the global timer */
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if (Timer_Milliseconds < 0xFF)
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Timer_Milliseconds++;
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if (SilenceTime < 0xFFFF)
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SilenceTime++;
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}
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/* Public access to the Silence Timer */
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uint16_t Timer_Silence(
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void)
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{
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uint16_t timer;
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BIT_CLEAR(TIMSK0, TOIE0);
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timer = SilenceTime;
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BIT_SET(TIMSK0, TOIE0);
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return timer;
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}
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/* Public reset of the Silence Timer */
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void Timer_Silence_Reset(
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void)
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{
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BIT_CLEAR(TIMSK0, TOIE0);
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SilenceTime = 0;
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BIT_SET(TIMSK0, TOIE0);
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}
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