nes-proj/platform/avr-ravenlcd/timer.c

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/*
* Copyright (c) 2008 Swedish Institute of Computer Science
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* * Neither the name of the copyright holders nor the names of
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/**
* \file
*
* \brief
* This file will configure the timer during LCD operation.
*
* \author
* Mike Vidales mavida404@gmail.com
*
*/
#include "lcd.h"
#include "timer.h"
/**
* \addtogroup lcd
* \{
*/
bool timer_flag;
/*---------------------------------------------------------------------------*/
/**
* \brief TIMER1 init for timer used by LCD.
*
* The FPU of 8MHz with a prescaler of 1024 equals 7812.5 timer ticks creating a
* resolution of 128us per tick.
*
* NOTE: The TIMER1 interrupt is not enabled in this routine
*/
void
timer_init(void)
{
/*
* Set TIMER1 output compare mode to clear on compare match for OC1A. Also
* set the pre-scaler to 1024.
*/
TCCR1B = (1 << WGM12)|(1 << CS12)|(1 << CS10);
/* Set TIMER1 output compare register approx. 1 sec resolution. */
OCR1A = _1_SEC;
}
/*---------------------------------------------------------------------------*/
/**
* \brief Start the timer.
*/
void
timer_start(void)
{
/* Clear TIMER1 timer counter value. */
TCNT1 = 0;
/* Enable TIMER1 output compare interrupt. */
TIMSK1 = (1 << OCIE1A);
}
/*---------------------------------------------------------------------------*/
/**
* \brief Stop the timer.
*/
void
timer_stop(void)
{
/* Disable TIMER1 output compare interrupt. */
TIMSK1 &= ~(1 << OCIE1A);
}
/*---------------------------------------------------------------------------*/
/**
* \brief This is the interrupt subroutine for the TIMER1 output match comparison.
*/
ISR
(TIMER1_COMPA_vect)
{
/* Set the irq flag. */
timer_flag = true;
}
/** \} */