137 lines
5.3 KiB
C
137 lines
5.3 KiB
C
/*
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* Copyright (c) 2013, Institute for Pervasive Computing, ETH Zurich
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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 the Contiki operating system.
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*/
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/**
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* \file
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* Moisture resource
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* \author
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* Harald Pichler <harald@the-develop.net>
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*/
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#include "contiki.h"
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#include <string.h>
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#include "rest-engine.h"
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#include "Arduino.h"
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#include "sketch.h"
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#define clockCyclesPerMicrosecond() ( F_CPU / 1000000L )
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#define clockCyclesToMicroseconds(a) ( (a) / clockCyclesPerMicrosecond() )
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#define microsecondsToClockCycles(a) ( (a) * clockCyclesPerMicrosecond() )
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unsigned long pulseIn(uint8_t pin, uint8_t state, unsigned long timeout)
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{
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// cache the port and bit of the pin in order to speed up the
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// pulse width measuring loop and achieve finer resolution. calling
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// digitalRead() instead yields much coarser resolution.
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uint8_t bit = digitalPinToBitMask(pin);
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uint8_t port = digitalPinToPort(pin);
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uint8_t stateMask = (state ? bit : 0);
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unsigned long width = 0; // keep initialization out of time critical area
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// convert the timeout from microseconds to a number of times through
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// the initial loop; it takes 16 clock cycles per iteration.
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unsigned long numloops = 0;
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unsigned long maxloops = microsecondsToClockCycles(timeout) / 16;
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// wait for any previous pulse to end
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while ((*portInputRegister(port) & bit) == stateMask)
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if (numloops++ == maxloops)
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return 0;
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// wait for the pulse to start
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while ((*portInputRegister(port) & bit) != stateMask)
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if (numloops++ == maxloops)
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return 0;
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// wait for the pulse to stop
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while ((*portInputRegister(port) & bit) == stateMask)
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width++;
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// convert the reading to microseconds. The loop has been determined
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// to be 10 clock cycles long and have about 16 clocks between the edge
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// and the start of the loop. There will be some error introduced by
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// the interrupt handlers.
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return clockCyclesToMicroseconds(width * 10 + 16);
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}
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static void res_get_handler(void *request, void *response, uint8_t *buffer, uint16_t preferred_size, int32_t *offset);
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/* A simple getter example. Returns the reading from the sensor with a simple etag */
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RESOURCE(res_distance,
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"title=\"Distance status\";rt=\"Distance\"",
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res_get_handler,
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NULL,
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NULL,
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NULL);
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static void
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res_get_handler(void *request, void *response, uint8_t *buffer, uint16_t preferred_size, int32_t *offset)
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{
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unsigned int accept = -1;
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REST.get_header_accept(request, &accept);
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long duration, distance;
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digitalWrite(TRIG_PIN, LOW);
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delayMicroseconds(2);
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digitalWrite(TRIG_PIN, HIGH);
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delayMicroseconds(20);
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digitalWrite(TRIG_PIN, LOW);
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duration = pulseIn(ECHO_PIN, HIGH, 500000);
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// found this computation in some arduino examples
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//distance = (duration/2) / 29.1;
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// to get millimeters (duration -20) / 3.18 is a good approach
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distance = (duration-20)/3.18;
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if(accept == -1 || accept == REST.type.TEXT_PLAIN) {
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REST.set_header_content_type(response, REST.type.TEXT_PLAIN);
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snprintf((char *)buffer, REST_MAX_CHUNK_SIZE, "%ld", distance);
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REST.set_response_payload(response, buffer, strlen((char *)buffer));
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} else if(accept == REST.type.APPLICATION_JSON) {
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REST.set_header_content_type(response, REST.type.APPLICATION_JSON);
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snprintf((char *)buffer, REST_MAX_CHUNK_SIZE, "{'distance':%ld}", distance);
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REST.set_response_payload(response, buffer, strlen((char *)buffer));
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} else {
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REST.set_response_status(response, REST.status.NOT_ACCEPTABLE);
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const char *msg = "Supporting content-types text/plain and application/json";
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REST.set_response_payload(response, msg, strlen(msg));
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}
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}
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