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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2007 by Michael Sevakis
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "config.h"
#include "system.h"
#include "kernel.h"
#include "timer.h"
#include "thread.h"
void tick_start(unsigned int interval_in_ms)
{
/*
* Based on default PCLK of 49.1568MHz - scaling chosen to give
* remainder-free result for tick interval of 10ms (100Hz)
* Timer input clock frequency =
* fPCLK / {prescaler value+1} / {divider value}
* TIMER_FREQ = 49156800 / 2
* 146300 = TIMER_FREQ / 21 / 8
* 49156800 = 19*11*(7)*7*5*5*(3)*2*2*2*2*2*2
* 21 = 7*3
*/
/* stop timer 4 */
TCON &= ~(1 << 20);
/* Set the count for timer 4 */
TCNTB4 = (TIMER_FREQ / TIMER234_PRESCALE / 8) * interval_in_ms / 1000;
/* Set the the prescaler value for timers 2,3, and 4 */
TCFG0 = (TCFG0 & ~0xff00) | ((TIMER234_PRESCALE-1) << 8);
/* DMA mode off, MUX4 = 1/16 */
TCFG1 = (TCFG1 & ~0xff0000) | 0x030000;
/* set manual bit */
TCON |= 1 << 21;
/* reset manual bit */
TCON &= ~(1 << 21);
/* interval mode */
TCON |= 1 << 22;
/* start timer 4 */
TCON |= (1 << 20);
/* timer 4 unmask interrupts */
INTMSK &= ~TIMER4_MASK;
}
#ifdef BOOTLOADER
void tick_stop(void)
{
bitset32(&INTMSK, TIMER4_MASK);
TCON &= ~(1 << 20);
SRCPND = TIMER4_MASK;
INTPND = TIMER4_MASK;
}
#endif
void TIMER4(void)
{
/* Run through the list of tick tasks */
call_tick_tasks();
SRCPND = TIMER4_MASK;
INTPND = TIMER4_MASK;
}
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