120 lines
2.9 KiB
C++
120 lines
2.9 KiB
C++
/* FreqCount Library, for measuring frequencies
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* http://www.pjrc.com/teensy/td_libs_FreqCount.html
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* Copyright (c) 2014 PJRC.COM, LLC - Paul Stoffregen <paul@pjrc.com>
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*
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* Version 1.1
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* 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, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "FreqCount.h"
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#include "util/FreqCountTimers.h"
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static uint16_t count_msw;
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static uint32_t count_prev;
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static volatile uint32_t count_output;
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static volatile uint8_t count_ready;
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static uint16_t gate_length;
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static uint16_t gate_index;
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void FreqCountClass::begin(uint16_t msec)
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{
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if (msec < 1) return;
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gate_index = 0;
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count_msw = 0;
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count_prev = 0;
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count_ready = 0;
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counter_init();
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gate_length = timer_init(msec);
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uint8_t status = SREG;
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cli();
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timer_start();
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timer_isr_latency_delay();
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counter_start();
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SREG = status;
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}
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uint8_t FreqCountClass::available(void)
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{
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return count_ready;
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}
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uint32_t FreqCountClass::read(void)
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{
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uint32_t count;
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uint8_t status;
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status = SREG;
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cli();
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#if defined(TIMER_USE_TIMER2) && F_CPU == 12000000L
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float correct = count_output * 0.996155;
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count = (uint32_t) (correct+0.5);
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#else
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count = count_output;
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#endif
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count_ready = 0;
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SREG = status;
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return count;
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}
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void FreqCountClass::end(void)
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{
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timer_shutdown();
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counter_shutdown();
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}
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ISR(TIMER_ISR_VECTOR)
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{
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uint16_t lsw, msw;
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uint32_t count;
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uint16_t index, length;
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lsw = counter_read();
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msw = count_msw;
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if (counter_overflow()) {
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counter_overflow_reset();
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if (lsw < 0xFA00) {
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msw = msw + 1;
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count_msw = msw;
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} else {
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count_msw = msw + 1;
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}
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}
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index = gate_index + 1;
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length = gate_length;
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if (index >= length) {
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gate_index = 0;
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count = ((uint32_t)msw << 16) + lsw;
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count_output = count - count_prev;
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count_prev = count;
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count_ready = 1;
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restore_other_interrupts();
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} else {
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if (index == length - 1) disable_other_interrupts();
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gate_index = index;
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}
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}
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FreqCountClass FreqCount;
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