sht1x: Initial implementation

This driver was developed with a DFRobot SHT10 Temperature and Humidity
sensor.  This driver should work on all SHT1X devices.

It requires a 10K pull-up resistor connected to the data pin.
The sensor can be run at differing voltages from 2.5v to 5v.

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

src/sht1x/sht1x_fti.c

@@ -0,0 +1,125 @@
+/*
+ * 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 "sht1x.h"
+#include "upm_fti.h"
+
+/**
+ * This file implements the Function Table Interface (FTI) for this sensor
+ */
+
+const char upm_sht1x_name[] = "SHT1X";
+const char upm_sht1x_description[] = "SHT1X Temperature and Humidity Sensor";
+const upm_protocol_t upm_sht1x_protocol[] = {UPM_GPIO, UPM_GPIO};
+const upm_sensor_t upm_sht1x_category[] = {UPM_TEMPERATURE, UPM_HUMIDITY};
+
+// forward declarations
+const void* upm_sht1x_get_ft(upm_sensor_t sensor_type);
+void* upm_sht1x_init_name();
+void upm_sht1x_close(void *dev);
+upm_result_t upm_sht1x_get_humidity(void *dev, float *value);
+upm_result_t upm_sht1x_get_temperature(void *dev, float *value,
+                                       upm_temperature_u unit);
+
+static const upm_sensor_ft ft =
+{
+  .upm_sensor_init_name = upm_sht1x_init_name,
+  .upm_sensor_close = upm_sht1x_close,
+};
+
+static const upm_temperature_ft tft =
+{
+  .upm_temperature_get_value = upm_sht1x_get_temperature,
+};
+
+static const upm_humidity_ft hft =
+{
+  .upm_humidity_get_value = upm_sht1x_get_humidity,
+};
+
+const void* upm_sht1x_get_ft(upm_sensor_t sensor_type)
+{
+  switch(sensor_type)
+    {
+    case UPM_SENSOR:
+      return &ft;
+    case UPM_HUMIDITY:
+      return &hft;
+    case UPM_TEMPERATURE:
+      return &tft;
+    default:
+      return NULL;
+    }
+}
+
+void* upm_sht1x_init_name()
+{
+  return NULL;
+}
+
+void upm_sht1x_close(void *dev)
+{
+  sht1x_close((sht1x_context)dev);
+}
+
+upm_result_t upm_sht1x_get_humidity(void *dev, float *value)
+{
+  upm_result_t rv;
+
+  if ((rv = sht1x_update((sht1x_context)dev)))
+    return rv;
+
+  *value = sht1x_get_humidity((sht1x_context)dev);
+
+  return UPM_SUCCESS;
+}
+
+upm_result_t upm_sht1x_get_temperature(void *dev, float *value,
+                                       upm_temperature_u unit)
+{
+  upm_result_t rv;
+
+  if ((rv = sht1x_update((sht1x_context)dev)))
+    return rv;
+
+  // always in C
+  float temp = sht1x_get_temperature((sht1x_context)dev);
+
+  switch (unit)
+    {
+    case CELSIUS:
+      *value = temp;
+      return UPM_SUCCESS;
+
+    case KELVIN:
+      *value = temp + 273.15;
+      return UPM_SUCCESS;
+
+    case FAHRENHEIT:
+      *value = temp * (9.0/5.0) + 32.0;
+      return UPM_SUCCESS;
+    }
+
+  return UPM_SUCCESS;
+}