HCSR04: Modifying implementation and adding examples

Signed-off-by: Abhishek Malik <abhishek.malik@intel.com>

src/hcsr04/hcsr04.h

@@ -0,0 +1,84 @@
+/*
+ * Author: Yevgeniy Kiveisha <yevgeniy.kiveisha@intel.com>
+ * Author: Rafael Neri <rafael.neri@gmail.com>
+ * Author: Jun Kato <i@junkato.jp>
+ * Contributions by: Abhishek Malik <abhishek.malik@intel.com>
+ * Copyright (c) 2014-2015 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.
+ */
+#pragma once
+
+#include <stdio.h>
+#include <string.h>
+#include <mraa/gpio.h>
+#include <sys/time.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef enum {
+    HCSR04_CM = 0,
+    HCSR04_INCH } HCSR04_U;
+
+/**
+ * @file hcsr04.h
+ * @library hcsr04
+ * @brief C API for the HCSR04 Ultrasonic Ranger sensor
+ *
+ * @include hcsr04.c
+ */
+
+typedef struct _hcsr04_context {
+    mraa_gpio_context        trigPin;
+    mraa_gpio_context        echoPin;
+    int                      interruptCounter;
+    long                     startTime;
+    long                     endTime;
+} *hcsr04_context;
+
+/**
+ * HCSR04 Initialization function
+ *
+ * @param triggerPin GPIO pin for trigger
+ * @param echoPin GPIO pin used for output from sensor
+ * @return hcsr04_context
+ */
+hcsr04_context hcsr04_init(int triggerPin, int echoPin);
+
+/**
+ * HCSR04 Close function
+ *
+ * @param dev hcsr04_context pointer
+ */
+void hcsr04_close(hcsr04_context dev);
+
+/**
+ * Function to get the distance from the HCSR04 sensor
+ *
+ * @param unit cm/inches
+ * @return distance in specified unit
+ */
+double hcsr04_get_distance(hcsr04_context dev, HCSR04_U unit);
+
+#ifdef __cplusplus
+}
+#endif