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      1 /*
      2  * Author: Jon Trulson <jtrulson (at) 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      */
     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      */
    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