contiki/examples/er-rest-example/resources/res-sht11.c

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/*
* Copyright (c) 2014, Nimbus Centre for Embedded Systems Research, Cork Institute of Technology.
* 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 the Contiki operating system.
*/
/**
* \file
* SHT11 Sensor Resource
*
* This is a simple GET resource that returns the temperature in Celsius
* and the humidity reading from the SHT11.
* \author
* Pablo Corbalan <paul.corbalan@gmail.com>
*/
#include "contiki.h"
#if PLATFORM_HAS_SHT11
#include <string.h>
#include "rest-engine.h"
#include "dev/sht11/sht11-sensor.h"
static void res_get_handler(void *request, void *response, uint8_t *buffer, uint16_t preferred_size, int32_t *offset);
/* Get Method Example. Returns the reading from temperature and humidity sensors. */
RESOURCE(res_sht11,
"title=\"Temperature and Humidity\";rt=\"Sht11\"",
res_get_handler,
NULL,
NULL,
NULL);
static void
res_get_handler(void *request, void *response, uint8_t *buffer, uint16_t preferred_size, int32_t *offset)
{
/* Temperature in Celsius (t in 14 bits resolution at 3 Volts)
* T = -39.60 + 0.01*t
*/
uint16_t temperature = ((sht11_sensor.value(SHT11_SENSOR_TEMP) / 10) - 396) / 10;
/* Relative Humidity in percent (h in 12 bits resolution)
* RH = -4 + 0.0405*h - 2.8e-6*(h*h)
*/
uint16_t rh = sht11_sensor.value(SHT11_SENSOR_HUMIDITY);
unsigned int accept = -1;
REST.get_header_accept(request, &accept);
if(accept == -1 || accept == REST.type.TEXT_PLAIN) {
REST.set_header_content_type(response, REST.type.TEXT_PLAIN);
snprintf((char *)buffer, REST_MAX_CHUNK_SIZE, "%u;%u", temperature, rh);
REST.set_response_payload(response, (uint8_t *)buffer, strlen((char *)buffer));
} else if(accept == REST.type.APPLICATION_XML) {
REST.set_header_content_type(response, REST.type.APPLICATION_XML);
snprintf((char *)buffer, REST_MAX_CHUNK_SIZE, "<Temperature =\"%u\" Humidity=\"%u\"/>", temperature, rh);
REST.set_response_payload(response, buffer, strlen((char *)buffer));
} else if(accept == REST.type.APPLICATION_JSON) {
REST.set_header_content_type(response, REST.type.APPLICATION_JSON);
snprintf((char *)buffer, REST_MAX_CHUNK_SIZE, "{'Sht11':{'Temperature':%u,'Humidity':%u}}", temperature, rh);
REST.set_response_payload(response, buffer, strlen((char *)buffer));
} else {
REST.set_response_status(response, REST.status.NOT_ACCEPTABLE);
const char *msg = "Supporting content-types text/plain, application/xml, and application/json";
REST.set_response_payload(response, msg, strlen(msg));
}
}
#endif /* PLATFORM_HAS_SHT11 */