joystick12: Added 2 axis analog joystick12 C sensor

Added the C source for the joystick12 with necessary changes to cmake,
examples, and docs.

Signed-off-by: Noel Eck <noel.eck@intel.com>

examples/c/CMakeLists.txt

@@ -101,6 +101,7 @@ add_example (emg)
 add_example (gsr)
 add_example (light)
 add_example (ldt0028)
+add_example (joystick12)
 
 # Custom examples
 add_custom_example (nmea_gps_i2c-example-c nmea_gps_i2c.c nmea_gps)

examples/c/joystick12.c

@@ -0,0 +1,86 @@
+/*
+ * 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 "joystick12.h"
+
+bool shouldRun = true;
+
+void sig_handler(int signo)
+{
+    if (signo == SIGINT)
+        shouldRun = false;
+}
+
+int main()
+{
+    signal(SIGINT, sig_handler);
+
+    //! [Interesting]
+
+    // Instantiate a joystick12 sensor
+    //    X = Analog pin A0
+    //    Y = Analog pin A1
+    joystick12_context sensor = joystick12_init(0, 1);
+
+    if (!sensor)
+    {
+        printf("joystick12_init() failed.\n");
+        return -1;
+    }
+
+    printf("Press any key to zero joystick...\n");
+    getchar();
+
+    // Zero x and y axis
+    joystick12_zero(sensor);
+
+    printf("Hold the X axis to the far neg or pos value, then press a key...\n");
+    getchar();
+    joystick12_calibrate_x(sensor);
+    printf("Hold the Y axis to the far neg or pos value, then press a key...\n");
+    getchar();
+    joystick12_calibrate_y(sensor);
+
+    // Every half a second, sample the sensor output
+    float x, y;
+    while (shouldRun)
+    {
+        joystick12_get_value_x(sensor, &x);
+        joystick12_get_value_y(sensor, &y);
+
+        printf("X: %5.02f Y: %5.02f\n", x, y);
+        usleep(500000);
+    }
+
+    //! [Interesting]
+
+    printf("Exiting\n");
+
+    joystick12_close(sensor);
+
+    return 0;
+}