lm35: add C driver and example; FTI; C++ wraps C

Signed-off-by: Jon Trulson <jtrulson@ics.com>

src/lm35/lm35.c

@@ -0,0 +1,106 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2016 Intel Corporation.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <assert.h>
+#include "lm35.h"
+
+lm35_context lm35_init(int pin, float aref)
+{
+    lm35_context dev =
+        (lm35_context)malloc(sizeof(struct _lm35_context));
+
+    if (!dev)
+        return NULL;
+
+    // make sure MRAA is initialized
+    int mraa_rv;
+    if ((mraa_rv = mraa_init()) != MRAA_SUCCESS)
+    {
+        printf("%s: mraa_init() failed (%d).\n", __FUNCTION__, mraa_rv);
+        lm35_close(dev);
+        return NULL;
+    }
+
+    // initialize the MRAA context
+
+    if (!(dev->aio = mraa_aio_init(pin)))
+    {
+        printf("%s: mraa_aio_init failed.\n", __FUNCTION__);
+        lm35_close(dev);
+
+        return NULL;
+    }
+
+    dev->ares = (float)((1 << mraa_aio_get_bit(dev->aio)) - 1);
+    dev->aref = aref;
+    dev->scale = 1.0;
+    dev->offset = 0.0;
+
+    return dev;
+}
+
+void lm35_close(lm35_context dev)
+{
+    assert(dev != NULL);
+
+    if (dev->aio)
+        mraa_aio_close(dev->aio);
+
+    free(dev);
+}
+
+upm_result_t lm35_get_temperature(const lm35_context dev, float *temperature)
+{
+    assert(dev != NULL);
+
+    int val = mraa_aio_read(dev->aio);
+    if (val < 0)
+    {
+        printf("%s: mraa_aio_read() failed\n", __FUNCTION__);
+        *temperature = 0.0;
+        return UPM_ERROR_OPERATION_FAILED;
+    }
+
+    // convert to mV
+    float mV = ((float)val * (dev->aref / dev->ares) * 1000.0);
+
+    // 10mV/degree C
+    *temperature = mV / 10.0;
+    *temperature = *temperature * dev->scale + (dev->offset * dev->scale);
+    return UPM_SUCCESS;
+}
+
+void lm35_set_offset(const lm35_context dev, float offset)
+{
+    assert(dev != NULL);
+
+    dev->offset = offset;
+}
+
+void lm35_set_scale(const lm35_context dev, float scale)
+{
+    assert(dev != NULL);
+
+    dev->scale = scale;
+}