mb1242.h

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/*
 * Copyright (c) 2017, James Jackson and Trey Henrichsen
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 *
 * * Neither the name of the copyright holder nor the names of its
 *   contributors may be used to endorse or promote products derived from
 *   this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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/*
 * Driver for the Maxbotix I2CXL-MaxSonar-EZ series sonar.
 * This has been made for and tested with the MB1242 sonar module,
 * but should work for the MB1202, MB1212, MB1222, and MB1232.
 */
#ifndef I2C_SONAR_H
#define I2C_SONAR_H

#include "i2c.h"

#include <cstdint>

// These 3 constants come from the spec sheet for the sonar
#define MB1242_DEFAULT_ADDRESS 112
#define MB1242_DEFAULT_REGISTER 0xFF
#define MB1242_PING_COMMAND 81

// Uncomment this to return raw distances instead of calibrated distances
// #define MB1242_RAW

#define MB1242_UPDATE_WAIT_MILLIS 50 // minimum time between calls of async_update that actually do something
// 50 ms is chosen because it will read only once per two calls to async_update, at max,
// and the spec sheet for the sonar recomends waiting 100 ms in between pings

class I2CSonar
{
private:
  uint32_t last_update_ms_;        // The last time that async_update was called
  uint32_t last_callback_ms_;      // The last time the sensor responded
  float value_;                    // the latest reading from the sensor
  bool new_data_;                  // Whether or not new data is ready to be returned
  I2C *i2c_;                       // The i2c object used for communication
  bool ready_to_ping_;             // Whether the sensor is ready to make another measurement
  uint8_t buffer_[2];              // for receiving data from the sensor
  bool sensor_present_{false};     // Flag of whether we have received data from the sensor
  bool sensor_initialized_{false}; // Whether the init function has been called yet

public:
  I2CSonar();
  void init(I2C *_i2c);
  bool present();
  float read();  // Returns the most recent reading, converted to meters, or 0 if there is none
  void update(); // Tries to either start a measurement, or read it from the sensor
  // update will do nothing if it has done something in the last MB1242_UPDATE_WAIT_MILLIS ms
  // Calling it more frequently won't break anything
  inline bool is_initialized() { return sensor_initialized_; }

  // Callbacks. For internal use only, but public so the I2C peripheral can call them
  void cb_start_read(uint8_t result);    // callback after the measure command has been sent to the sensor
  void cb_finished_read(uint8_t result); // callback after reading from the sensor has finished
};

#endif