DS7505.hpp

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00032 
00033 #ifndef DS7505_HPP
00034 #define DS7505_HPP
00035 
00036 #include <stdint.h>
00037 
00038 namespace mbed { class I2C; }
00039 
00040 /// Interface to the DS7505 temperature sensor.
00041 class DS7505 {
00042 public:
00043   enum Result { Success, Hardware_Failure, Out_of_Range };
00044 
00045   /// @param I2C_interface A configured I2C interface to use for communication.
00046   /// @param I2C_address Device bus address in mbed format.
00047   DS7505 (mbed::I2C & I2C_interface, uint8_t I2C_address);
00048 
00049   /// Set the resolution for temperature conversions.
00050   /// @param resolution Number of decimal bit from 1 to 4.
00051   Result set_resolution(uint8_t resolution);
00052 
00053   /// Reads the current temperature with an exponent of 10^-2.
00054   /// @note Compatible with Bluetooth characteristic:
00055   /// org.bluetooth.characteristic.temperature.
00056   Result read_current_temp(int16_t & temperature) const;
00057 
00058   /// Reads the current temperature as a floating point value.
00059   Result read_current_temp(double & temperature) const;
00060 
00061   /// Reads the current temperature as an integer value.
00062   Result read_current_temp(int8_t & temperature) const;
00063 
00064 private:
00065   /// Bit resolution of temperature conversions.
00066   enum Config_Resolution {
00067     Config_9b_Res = 0x00,
00068     Config_10b_Res = 0x20,
00069     Config_11b_Res = 0x40,
00070     Config_12b_Res = 0x60
00071   };
00072 
00073   /// DS7505 Register addresses.
00074   enum Register {
00075     Temperature_Reg = 0x00,
00076     Configuration_Reg = 0x01,
00077     Thyst_Reg = 0x02,
00078     Tos_Reg = 0x03
00079   };
00080 
00081   /// Represents a DS7505 configuration.
00082   struct Config {
00083     Config_Resolution resolution;
00084     bool enable_shutdown_mode;
00085 
00086     Config(Config_Resolution resolution, bool enable_shutdown_mode)
00087         : resolution(resolution), enable_shutdown_mode(enable_shutdown_mode) {}
00088   };
00089 
00090   /// @note Mark as mutable to allow manipulation by read_temp_sensor().
00091   mutable Config m_current_config;
00092 
00093   mbed::I2C & m_I2C_interface;
00094   uint8_t m_I2C_address;
00095 
00096   /// Returns the maximum time needed in milliseconds for a sample at the
00097   /// specified resolution.
00098   static uint8_t get_measure_delay_ms(Config_Resolution resolution);
00099 
00100   /// Reads the current temperature via I2C. Assumes that the I2C register
00101   /// pointer is already set to the temperature register.
00102   /// @param sensor_data
00103   /// Output for raw data from DS7505 with upper and lower bytes combined.
00104   /// @returns True on success.
00105   bool read_temp_sensor_data(uint16_t & sensor_data) const;
00106 
00107   /// Reads the current temperature with support for shutdown mode.
00108   /// @param sensor_data Output for raw data from DS7505 with upper and lower
00109   /// bytes combined.
00110   /// @returns Success or Hardware_Failure.
00111   Result read_temp_sensor(uint16_t & sensor_data) const;
00112 
00113   /// Sets the I2C register pointer for the next operation.
00114   /// @param pointer_reg Desired register to set.
00115   /// @returns True on success.
00116   /// @note Allow marking const since not public.
00117   bool set_register_pointer(Register pointer_reg) const;
00118 
00119   /// Writes to a device register via I2C.
00120   /// @param write_reg Register to write to.
00121   /// @param write_val Value to write to the register.
00122   /// @returns True on success.
00123   /// @note Allow marking const since not public
00124   bool write_register(Register write_reg, uint8_t write_val) const;
00125 
00126   /// Writes the current configuration via I2C.
00127   /// @returns True on success.
00128   /// @note Allow marking const since not public
00129   bool write_current_config() const;
00130 };
00131 
00132 #endif