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+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 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 <string>
+#include <stdint.h>
+#include <sys/time.h>
+#include <mraa/gpio.hpp>
+
+namespace upm {
+
+ /**
+ * @brief DFRobot Wheel Encoder library
+ * @defgroup wheelencoder libupm-wheelencoder
+ * @ingroup dfrobot gpio other
+ */
+
+ /**
+ * @library wheelencoder
+ * @sensor wheelencoder
+ * @comname DFRobot Wheel Encoder
+ * @type other
+ * @man dfrobot
+ * @web http://www.dfrobot.com/index.php?route=product/product&product_id=98
+ * @con gpio
+
+ * @brief API for the DFRobot Wheel Encoder
+ *
+ * This sensor was developed for the DFRobot Wheel Encoder, though
+ * it could be used for any counting time-based task.
+ *
+ * When you instantiate a class of this type, the gpio pin specified
+ * is connected to an interrupt. Whenever a low to high transition
+ * occurs on the gpio pin, the internal counter is incremented by
+ * one.
+ *
+ * This class also includes a millisecond counter, so that you can
+ * correlate the number of counts to a time period for calculating
+ * an RPM or other value as needed.
+ *
+ * @image html wheelencoder.jpg
+ * @snippet wheelencoder.cxx Interesting
+ */
+ class WheelEncoder {
+ public:
+
+ /**
+ * DFRobot Wheel Encoder sensor constructor
+ *
+ * @param pin Digital pin to use
+ */
+ WheelEncoder(int pin);
+
+ /**
+ * WheelEncoder destructor
+ */
+ ~WheelEncoder();
+
+ /**
+ * Returns the number of milliseconds elapsed since initClock()
+ * was last called.
+ *
+ * @return Elapsed milliseconds
+ */
+ uint32_t getMillis();
+
+ /**
+ * Resets the clock
+ *
+ */
+ void initClock();
+
+ /**
+ * Resets the counter to 0. The counter should be
+ * stopped via stopCounter() prior to calling this function.
+ *
+ */
+ void clearCounter() { m_counter = 0; };
+
+ /**
+ * Starts the counter. This function will also clear the current
+ * count and reset the clock.
+ *
+ */
+ void startCounter();
+
+ /**
+ * Stops the counter
+ *
+ */
+ void stopCounter();
+
+ /**
+ * Gets the current counter value
+ *
+ * @return counter value
+ */
+ uint32_t counter() { return m_counter; };
+
+ protected:
+ mraa::Gpio m_gpio;
+ static void wheelISR(void *ctx);
+
+ private:
+ volatile uint32_t m_counter;
+ struct timeval m_startTime;
+ bool m_isrInstalled;
+ };
+}
+
+