104 lines
3.0 KiB
C++
104 lines
3.0 KiB
C++
/*
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* Author: Jun Kato <i@junkato.jp>
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* Copyright (c) 2015 Jun Kato.
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*
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* Thanks to Seeed Studio for a working arduino sketch
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in 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,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <iostream>
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#include <unistd.h>
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#include <stdlib.h>
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#include <functional>
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#include "ultrasonic.hpp"
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using namespace upm;
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UltraSonic::UltraSonic (int pin) {
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m_name = "UltraSonic";
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mraa_init();
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// setup pin
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m_pinCtx = mraa_gpio_init(pin);
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if (m_pinCtx == NULL) {
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fprintf (stderr, "Are you sure that pin%d you requested is valid on your platform?", pin);
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exit (1);
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}
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mraa_gpio_use_mmaped(m_pinCtx, 1);
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mraa_gpio_isr (m_pinCtx, MRAA_GPIO_EDGE_BOTH,
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&signalISR, this);
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}
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UltraSonic::~UltraSonic () {
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// close pin
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mraa_gpio_isr_exit(m_pinCtx);
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mraa_gpio_close (m_pinCtx);
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}
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int
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UltraSonic::getDistance () {
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// output trigger signal
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mraa_gpio_dir(m_pinCtx, MRAA_GPIO_OUT);
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mraa_gpio_write(m_pinCtx, LOW);
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usleep(2);
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mraa_gpio_write(m_pinCtx, HIGH);
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usleep(5);
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mraa_gpio_write(m_pinCtx, LOW);
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// wait for the pulse,
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m_doWork = true;
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m_InterruptCounter = 0;
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mraa_gpio_dir(m_pinCtx, MRAA_GPIO_IN);
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// though do not wait over 25 [ms].
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int timer = 0;
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while (m_doWork && timer++ < 5) {
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// in 25 [ms], sound travels 25000 / 29 / 2 = 431 [cm],
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// which is more than 400 [cm], the max distance measurable with this sensor.
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usleep(5 * 1000); // 5 [ms]
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}
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// calc diff
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long diff = m_FallingTimeStamp.tv_usec - m_RisingTimeStamp.tv_usec;
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diff += (m_FallingTimeStamp.tv_sec - m_RisingTimeStamp.tv_sec) * 1000000;
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return timer >= 5 ? 0 : diff;
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}
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void
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UltraSonic::signalISR(void *ctx) {
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upm::UltraSonic *This = (upm::UltraSonic *)ctx;
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This->ackEdgeDetected();
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}
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void
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UltraSonic::ackEdgeDetected () {
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if (++m_InterruptCounter % 2 == 0) {
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gettimeofday(&m_FallingTimeStamp, NULL);
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m_doWork = false;
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} else {
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gettimeofday(&m_RisingTimeStamp, NULL);
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}
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}
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