1 /*
2  * Author: Jon Trulson <jtrulson@ics.com>
3  * Copyright (c) 2015 Intel Corporation.
4  *
5  * Permission is hereby granted, free of charge, to any person obtaining
6  * a copy of this software and associated documentation files (the
7  * "Software"), to deal in the Software without restriction, including
8  * without limitation the rights to use, copy, modify, merge, publish,
9  * distribute, sublicense, and/or sell copies of the Software, and to
10  * permit persons to whom the Software is furnished to do so, subject to
11  * the following conditions:
12  *
13  * The above copyright notice and this permission notice shall be
14  * included in all copies or substantial portions of the Software.
15  *
16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
19  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
20  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
21  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
22  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23  */
24 #pragma once
25 
26 #include <string>
27 #include <stdint.h>
28 #include <sys/time.h>
29 #include <mraa/gpio.hpp>
30 
31 namespace upm {
32 
33   /**
34    * @brief DFRobot Wheel Encoder library
35    * @defgroup wheelencoder libupm-wheelencoder
36    * @ingroup dfrobot gpio other
37    */
38 
39   /**
40    * @library wheelencoder
41    * @sensor wheelencoder
42    * @comname DFRobot Wheel Encoder
43    * @type other
44    * @man dfrobot
45    * @web http://www.dfrobot.com/index.php?route=product/product&product_id=98
46    * @con gpio
47 
48    * @brief API for the DFRobot Wheel Encoder
49    *
50    * This sensor was developed for the DFRobot Wheel Encoder, though
51    * it could be used for any counting time-based task.
52    *
53    * When you instantiate a class of this type, the gpio pin specified
54    * is connected to an interrupt.  Whenever a low to high transition
55    * occurs on the gpio pin, the internal counter is incremented by
56    * one.
57    *
58    * This class also includes a millisecond counter, so that you can
59    * correlate the number of counts to a time period for calculating
60    * an RPM or other value as needed.
61    *
62    * @snippet wheelencoder.cxx Interesting
63    */
64   class WheelEncoder {
65   public:
66 
67     /**
68      * DFRobot Wheel Encoder sensor constructor
69      *
70      * @param pin Digital pin to use
71      */
72     WheelEncoder(int pin);
73 
74     /**
75      * WheelEncoder destructor
76      */
77     ~WheelEncoder();
78 
79     /**
80      * Returns the number of milliseconds elapsed since initClock()
81      * was last called.
82      *
83      * @return Elapsed milliseconds
84      */
85     uint32_t getMillis();
86 
87     /**
88      * Resets the clock
89      *
90      */
91     void initClock();
92 
93     /**
94      * Resets the counter to 0. The counter should be
95      * stopped via stopCounter() prior to calling this function.
96      *
97      */
clearCounter()98     void clearCounter() { m_counter = 0; };
99 
100     /**
101      * Starts the counter.  This function will also clear the current
102      * count and reset the clock.
103      *
104      */
105     void startCounter();
106 
107     /**
108      * Stops the counter
109      *
110      */
111     void stopCounter();
112 
113     /**
114      * Gets the current counter value
115      *
116      * @return counter value
117      */
counter()118     uint32_t counter() { return m_counter; };
119 
120   protected:
121     mraa::Gpio m_gpio;
122     static void wheelISR(void *ctx);
123 
124   private:
125     volatile uint32_t m_counter;
126     struct timeval m_startTime;
127     bool m_isrInstalled;
128   };
129 }
130 
131 
132