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>

examples/c/CMakeLists.txt

@@ -118,6 +118,7 @@ add_example (moisture)
 add_example (led)
 add_example (ds18b20)
 add_example (dfrec)
+add_example (sht1x)
 
 # Custom examples
 add_custom_example (nmea_gps_i2c-example-c nmea_gps_i2c.c nmea_gps)

examples/c/sht1x.c

@@ -0,0 +1,77 @@
+/*
+ * 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 <unistd.h>
+#include <signal.h>
+
+#include "sht1x.h"
+
+bool shouldRun = true;
+
+void sig_handler(int signo)
+{
+  if (signo == SIGINT)
+    shouldRun = false;
+}
+
+int main()
+{
+  signal(SIGINT, sig_handler);
+
+//! [Interesting]
+
+  // Instantiate a SHT1X sensor using D2 as the clock, and D3 as the
+  // data pin.
+  sht1x_context sensor = sht1x_init(2, 3);
+
+  if (!sensor)
+    {
+      printf("sht1x_init() failed.\n");
+      return 1;
+    }
+
+  // Every 2 seconds, update and print values
+  while (shouldRun)
+    {
+      if (sht1x_update(sensor))
+        {
+          printf("sht1x_update() failed, exiting.\n");
+          break;
+        }
+
+      printf("Temperature: %f C\n", sht1x_get_temperature(sensor));
+      printf("Humidity:    %f RH\n", sht1x_get_humidity(sensor));
+      printf("\n");
+
+      sleep(2);
+    }
+
+//! [Interesting]
+
+  printf("Exiting\n");
+
+  sht1x_close(sensor);
+
+  return 0;
+}