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new timer setup routines.

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maralvira 2011-01-17 15:51:19 +00:00
parent b3c8c14b7d
commit ce92a90e58
1 changed files with 97 additions and 0 deletions
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cpu/mc1322x/lib/tmr.c Normal file
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/*
* Copyright (c) 2010, Mariano Alvira <mar@devl.org> and other contributors
* to the MC1322x project (http://mc1322x.devl.org)
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE 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 INSTITUTE 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.
*
* This file is part of libmc1322x: see http://mc1322x.devl.org
* for details.
*
* $Id: tmr.c,v 1.1 2011/01/17 15:51:19 maralvira Exp $
*/
#include <mc1322x.h>
#include <stdlib.h>
#include "tmr.h"
/* Initialize timer. This just counts and interrupts, doesn't drive an output.
timer_num = 0, 1, 2, 3
rate = desired rate in Hz,
enable_int = whether to enable an interrupt on every cycle
Returns actual timer rate. */
uint32_t timer_setup_ex(int timer_num, uint32_t rate, int enable_int)
{
uint32_t actual_rate;
volatile struct TMR_struct *timer = TMR_ADDR(timer_num);
int log_divisor = 0;
uint32_t period;
/* Turn timer off */
TMR0->ENBL &= ~(1 << timer_num);
/* Calculate optimal rate */
for (log_divisor = 0; log_divisor < 8; log_divisor++)
{
int denom = (rate * (1 << log_divisor));
period = (REF_OSC + denom/2) / denom;
if (period <= 65535)
break;
}
if (log_divisor >= 8)
{
period = 65535;
log_divisor = 7;
}
if (period < 2) period = 2;
actual_rate = REF_OSC / (period * (1 << log_divisor));
/* Set up timer */
timer->LOAD = 0;
timer->CMPLD1 = (period - 1);
timer->COMP1 = timer->CMPLD1;
timer->CNTR = timer->LOAD;
timer->SCTRL = 0;
timer->CSCTRLbits = (struct TMR_CSCTRL) {
.CL1 = 0x01, // Reload COMP1 when COMP1 matches
};
timer->CTRLbits = (struct TMR_CTRL) {
.COUNT_MODE = 1, // Count rising edge of primary source
.PRIMARY_CNT_SOURCE = 8 + log_divisor, // Peripheral clock divided by (divisor)
.LENGTH = 1, // At compare, reset to LOAD
};
TMR0->ENBL |= (1 << timer_num);
if (enable_int) {
enable_irq(TMR);
timer->SCTRLbits.TCFIE = 1;
}
return actual_rate;
}