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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.h>
     30 
     31 namespace upm {
     32 
     33 /**
     34  * @brief Grove Rotary Encoder library
     35  * @defgroup rotaryencoder libupm-rotaryencoder
     36  * @ingroup seeed gpio other hak
     37  */
     38 /**
     39  * @library rotaryencoder
     40  * @sensor rotaryencoder
     41  * @comname Grove Rotary Encoder
     42  * @type other
     43  * @man seeed
     44  * @web http://www.seeedstudio.com/wiki/Grove_-_Encoder
     45  * @con gpio
     46  * @kit hak
     47  *
     48  * @brief API for the Grove Rotary Encoder
     49  *
     50  * UPM module for the Grove rotary encoder. This rotary encoder
     51  * encodes a rotation signal into electronic pulses that can be used
     52  * to measure rotation and direction. It is useful in cases where a
     53  * rotary knob is required, but using a potentiometer is not
     54  * desirable. A rotary encoder can turn a full 360 degrees
     55  * without a stop and does not place a resistive load on the
     56  * circuit, as is the case with a potentiometer.
     57  *
     58  * This module maintains a position that is incremented or
     59  * decremented according to the rotation on the encoder.
     60  *
     61  * @image html rotaryencoder.jpg
     62  * @snippet rotaryencoder.cxx Interesting
     63  */
     64   class RotaryEncoder {
     65   public:
     66     /**
     67      * RotaryEncoder constructor
     68      *
     69      * @param pinA Digital pin to use for signal A
     70      * @param pinB Digital pin to use for signal B
     71      */
     72     RotaryEncoder(int pinA, int pinB);
     73     /**
     74      * RotaryEncoder destructor
     75      */
     76     ~RotaryEncoder();
     77 
     78     /**
     79      * Resets the position to a given number; default is 0.
     80      *
     81      * @param count Integer to initialize the position to
     82      */
     83     void initPosition(int count=0);
     84 
     85     /**
     86      * Gets the position value
     87      *
     88      */
     89     int position();
     90 
     91   private:
     92     /**
     93      * Interrupt service routine (ISR) for signal A
     94      *
     95      * @param ctx User context for the ISR (*this pointer)
     96      */
     97     static void signalAISR(void *ctx);
     98 
     99     volatile int m_position;
    100     mraa_gpio_context m_gpioA;
    101     mraa_gpio_context m_gpioB;
    102   };
    103 }
    104 
    105 
    106