analog_digital_converter.h

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/*
 * Copyright (c) 2020, Richard 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"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef ADC_H
#define ADC_H

#include "system.h"

class AnalogDigitalConverter
{
public:
  void init(const ADCHardwareStruct *adc_def);
  uint8_t add_channel(uint8_t channel);
  // Returns a value between 0 and RAW_READING_MAX. 0 represents 0V, and RAW_READING_MAX
  // represents REFERENCE_VOLTAGE
  // The parameter, index, is the return value from add_channel when the channel was added
  uint16_t read(uint8_t index) const;
  bool is_initialized() const;
  uint8_t get_current_channel_count() const;

  static constexpr double REFERENCE_VOLTAGE{3.3};
  static constexpr uint16_t RAW_READING_MAX{0xFFF};
  static constexpr uint16_t NO_READING{0xFFFF};
  static constexpr uint8_t CHANNEL_COUNT{16};

private:
  const ADCHardwareStruct *adc_def_;
  bool is_initialized_{false};
  uint8_t current_channels;

  // These two constants are used for adjusting the ADC configuration when a channel is added
  static constexpr uint32_t SQR1_CHANNEL_COUNT_MASK{~0xFF0FFFFF};
  static constexpr uint8_t SQR1_CHANNEL_COUNT_OFFSET{20};

  volatile uint32_t buffer[CHANNEL_COUNT];

  void init_dma();
  void start_dma();
};

#endif // ADC_H