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110 lines
2.9 KiB
C
110 lines
2.9 KiB
C
/*
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* Author: Jon Trulson <jtrulson@ics.com>
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* Copyright (c) 2016 Intel Corporation.
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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 <assert.h>
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#include <string.h>
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#include "lm35.h"
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lm35_context lm35_init(int pin, float aref)
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{
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lm35_context dev =
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(lm35_context)malloc(sizeof(struct _lm35_context));
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if (!dev)
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return NULL;
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memset((void *)dev, 0, sizeof(struct _lm35_context));
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// make sure MRAA is initialized
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int mraa_rv;
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if ((mraa_rv = mraa_init()) != MRAA_SUCCESS)
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{
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printf("%s: mraa_init() failed (%d).\n", __FUNCTION__, mraa_rv);
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lm35_close(dev);
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return NULL;
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}
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// initialize the MRAA context
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if (!(dev->aio = mraa_aio_init(pin)))
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{
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printf("%s: mraa_aio_init failed.\n", __FUNCTION__);
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lm35_close(dev);
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return NULL;
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}
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dev->ares = (float)((1 << mraa_aio_get_bit(dev->aio)) - 1);
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dev->aref = aref;
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dev->scale = 1.0;
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dev->offset = 0.0;
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return dev;
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}
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void lm35_close(lm35_context dev)
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{
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assert(dev != NULL);
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if (dev->aio)
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mraa_aio_close(dev->aio);
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free(dev);
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}
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upm_result_t lm35_get_temperature(const lm35_context dev, float *temperature)
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{
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assert(dev != NULL);
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int val = mraa_aio_read(dev->aio);
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if (val < 0)
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{
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printf("%s: mraa_aio_read() failed\n", __FUNCTION__);
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*temperature = 0.0;
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return UPM_ERROR_OPERATION_FAILED;
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}
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// convert to mV
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float mV = ((float)val * (dev->aref / dev->ares) * 1000.0);
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// 10mV/degree C
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*temperature = mV / 10.0;
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*temperature = *temperature * dev->scale + (dev->offset * dev->scale);
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return UPM_SUCCESS;
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}
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void lm35_set_offset(const lm35_context dev, float offset)
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{
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assert(dev != NULL);
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dev->offset = offset;
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}
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void lm35_set_scale(const lm35_context dev, float scale)
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{
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assert(dev != NULL);
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dev->scale = scale;
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}
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