ds18b20.hpp

/*
 * Author: Jon Trulson <jtrulson@ics.com>
 * Copyright (c) 2016 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 <iostream>
#include <map>

#include <stdlib.h>
#include <unistd.h>
#include <string.h>

#include <mraa/common.hpp>
#include <mraa/uart_ow.hpp>

#define DS18B20_DEFAULT_UART 0

namespace upm {
  class DS18B20 {
  public:

    // The family code for these devices.  We handle all of them that
    // are found on the bus.
    static const uint8_t DS18B20_FAMILY_CODE = 0x28;

    // commands
    typedef enum {
      CMD_CONVERT                         = 0x44, // start a temp conversion
      CMD_WRITE_SCRATCHPAD                = 0x4e,
      CMD_READ_SCRATCHPAD                 = 0xbe,
      CMD_COPY_SCRATCHPAD                 = 0x48, // copy scratchpad to EEPROM
      CMD_RECALL_EEPROM                   = 0xb8, // copy EEPROM to scratchpad
      CMD_READ_POWER_SUPPLY               = 0xb4  // parasitically powered?
    } CMD_T;

    // config register (scratchpad[4])
    typedef enum {
      CFG_RESOLUTION_R0                   = 0x20,
      CFG_RESOLUTION_R1                   = 0x40,
      _CFG_RESOLUTION_MASK                = 3,
      _CFG_RESOLUTION_SHIFT               = 5

      // all other bits reserved and non-writable
    } CFG_BITS_T;

    typedef enum {
      RESOLUTION_9BITS                    = 0, // 93.75ms (tconv/8)
      RESOLUTION_10BITS                   = 1, // 187.5 (tconv/4)
      RESOLUTION_11BITS                   = 2, // 375ms (tconv/2)
      RESOLUTION_12BITS                   = 3  // 750ms (tconv)
    } RESOLUTIONS_T;

    DS18B20(int uart=DS18B20_DEFAULT_UART);

    ~DS18B20();

    void init();

    void update(int index=-1);

    float getTemperature(int index, bool fahrenheit=false);

    void setResolution(int index, RESOLUTIONS_T res);

    void copyScratchPad(int index);

    void recallEEPROM(int index);

    int devicesFound()
    {
      return m_devicesFound;
    }

    std::string getId(int index)
    {
      if (index < 0 || index >= m_devicesFound)
        {
          throw std::out_of_range(std::string(__FUNCTION__) +
                                  ": device index out of range");
        }
      return m_deviceMap[index].id;
    }

  protected:
    mraa::UartOW m_uart;

    // the total number of devices found
    int m_devicesFound;

    // this struct will generate SWIG warnings on build, but as it's not
    // exposed outside the class, they can be safely ignored

    // data we need to store for each sensor we are dealing with
    typedef struct {
      std::string id;           // 8-byte romcode id
      float temperature;
      RESOLUTIONS_T resolution;
    } sensor_info_t;

    std::map<int, sensor_info_t> m_deviceMap;

  private:
    // internal utility function to read temperature from a single
    // device
    float readSingleTemp(int index);
  };
}