mma7361: Initial implementation

This driver implements support for the DFRobot MMA7361 analog
accelerometer.  It supports 3 axes with a selectable 1.5G and 6G
sensitivity. It is not really meant for navigation, but rather for
uses such as orientation and freefall detection.

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

examples/c/CMakeLists.txt

@@ -88,3 +88,4 @@ link_directories (${MRAA_LIBDIR})
 #  grove* will use module grove
 add_example (dfrph)
 add_example (vk2828u7)
+add_example (mma7361)

examples/c/mma7361.c

@@ -0,0 +1,85 @@
+/*
+ * 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 "mma7361.h"
+
+bool shouldRun = true;
+
+void sig_handler(int signo)
+{
+  if (signo == SIGINT)
+    shouldRun = false;
+}
+
+int main()
+{
+  signal(SIGINT, sig_handler);
+
+//! [Interesting]
+
+  // Instantiate a MMA7361 sensor on analog pins A0 (X), A1 (Y) A2
+  // (Z), selftest pin on D2, sleep pin on D3 nd an analog reference
+  // value of 5.0.  The freefall pin and the range pin are unused
+  // (-1).
+  mma7361_context sensor = mma7361_init(0, 1, 2, 2, 3, -1, -1, 5.0);
+
+  if (!sensor)
+    {
+      printf("mma7361_init() failed.\n");
+      return(1);
+    }
+
+  // 1.5g (true = 6g)
+  mma7361_set_range(sensor, false);
+
+  // Every 10th of a second, update and print values
+
+  while (shouldRun)
+    {
+      mma7361_update(sensor);
+
+      float x, y, z;
+
+      mma7361_get_acceleration(sensor, &x, &y, &z);
+      printf("Acceleration x = %f y = %f z = %f\n",
+             x, y, z);
+
+      mma7361_get_volts(sensor, &x, &y, &z);
+      printf("Volts x = %f y = %f z = %f\n\n",
+             x, y, z);
+
+      usleep(100000);
+    }
+
+//! [Interesting]
+
+  printf("Exiting...\n");
+
+  mma7361_close(sensor);
+
+  return 0;
+}