97 lines
3.2 KiB
C
97 lines
3.2 KiB
C
/*
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* Copyright (c) 2010, Mariano Alvira <mar@devl.org> and other contributors
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* to the MC1322x project (http://mc1322x.devl.org)
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of libmc1322x: see http://mc1322x.devl.org
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* for details.
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*
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*
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*/
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#include <mc1322x.h>
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#include <stdlib.h>
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#include "tmr.h"
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/* Initialize timer. This just counts and interrupts, doesn't drive an output.
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timer_num = 0, 1, 2, 3
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rate = desired rate in Hz,
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enable_int = whether to enable an interrupt on every cycle
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Returns actual timer rate. */
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uint32_t timer_setup_ex(int timer_num, uint32_t rate, int enable_int)
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{
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uint32_t actual_rate;
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volatile struct TMR_struct *timer = TMR_ADDR(timer_num);
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int log_divisor = 0;
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uint32_t period;
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/* Turn timer off */
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TMR0->ENBL &= ~(1 << timer_num);
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/* Calculate optimal rate */
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for (log_divisor = 0; log_divisor < 8; log_divisor++)
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{
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int denom = (rate * (1 << log_divisor));
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period = (REF_OSC + denom/2) / denom;
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if (period <= 65535)
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break;
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}
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if (log_divisor >= 8)
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{
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period = 65535;
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log_divisor = 7;
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}
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if (period < 2) period = 2;
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actual_rate = REF_OSC / (period * (1 << log_divisor));
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/* Set up timer */
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timer->LOAD = 0;
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timer->CMPLD1 = (period - 1);
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timer->COMP1 = timer->CMPLD1;
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timer->CNTR = timer->LOAD;
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timer->SCTRL = 0;
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timer->CSCTRLbits = (struct TMR_CSCTRL) {
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.CL1 = 0x01, // Reload COMP1 when COMP1 matches
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};
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timer->CTRLbits = (struct TMR_CTRL) {
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.COUNT_MODE = 1, // Count rising edge of primary source
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.PRIMARY_CNT_SOURCE = 8 + log_divisor, // Peripheral clock divided by (divisor)
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.LENGTH = 1, // At compare, reset to LOAD
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};
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TMR0->ENBL |= (1 << timer_num);
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if (enable_int) {
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enable_irq(TMR);
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timer->SCTRLbits.TCFIE = 1;
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}
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return actual_rate;
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}
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