driver-ms56xx/include/sta/drivers/MS56xx.hpp

#ifndef STA_SENSORS_MS5607_HPP
#define STA_SENSORS_MS5607_HPP

#include <sta/bus/spi/device.hpp>
#include <sta/bus/i2c/device.hpp>

#include <sta/endian.hpp>

// Important: The pin CSB shall be connected to VDD or GND (do not leave unconnected!).

/**
 * @brief MS56xx address when the CS pin is connected to GND.
 * 
 */
#define MS56XX_ADDRESS_CS_LOW       (uint8_t)0x77

/**
 * @brief MS56xx address when the CS pin is connected to VDD.
 * 
 */
#define MS56XX_ADDRESS_CS_HIGH      (uint8_t)0x76


namespace sta 
{
    /**
     * @brief Driver class for communicating with the MS56xx pressure sensor via SPI.
     * 
     */
    class MS56xx {
    public:
        /**
		 * @brief Signature for delay msec function.
		 */
        using DelayUsFunc = void (*)(uint32_t);

        /**
         * @brief Different OSR levels for the sensor
         * 
         */
        enum OsrLevel {
            _256        = 0,
            _512        = 1,
            _1024       = 2,
            _2048       = 3,
            _4096       = 4
        };

        /**
         * @brief Different units supported by the pressure sensor.
         * 
         */
        enum Unit
        {
            hPa,
            Pa,
            mbar
        };

        /**
         * @brief The types of physical interfaces used for communication with the sensor.
         * 
         */
        enum Intf
        {
            SPI,
            I2C
        };

        /**
         * @brief All possible commands to send to the sensor
         * 
         */
        enum Operations {
            RESET = 0x1E,
            READ_PROM = 0xA0,
            D1_CONVERSION = 0x40,
            D2_CONVERSION = 0x50,
            ADC_RESULT = 0x00
        };

        /**
         * @brief SPI driver for the MS56xx pressure sensor series.
         * 
         * @param device The SPI device for bus communication.
         * @param delay Function for triggering microsecond delays.
         * @param osr The oversampling rate for the sensor.
         * 
         * @note Set PS pin to low for SPI. Maximum SPI frequency 20MHz, mode 0 and 3 are supported.
         */
        MS56xx(SPIDevice * device, DelayUsFunc delay, OsrLevel osr = OsrLevel::_1024);

        /**
         * @brief I2C driver for the MS56xx pressure sensor series.
         * 
         * @param device The I2C device for bus communication.
         * @param delay Function for triggering microsecond delays.
         * @param osr The oversampling rate for the sensor.
         * 
         * @note Set PS pin to high for I2C. Chip select pin represents LSB of address.
         */
        MS56xx(I2CDevice * device, DelayUsFunc delay, OsrLevel osr = OsrLevel::_1024);

        /**
         * @brief Initialize the driver. Computes the pressure value at altitude 0.
         * 
         * @return True if successful, false otherwise.
         */
        bool init();

        /**
         * @brief Set the oversampling rate.
         * 
         * @param osr The new oversampling rate.
         */
        void setOsr(OsrLevel osr);

        /**
         * @brief Reads the current pressure value from the sensor. Obtains the temperature value from the interal sensor.
         * 
         * @param unit Specifies the unit for the pressure measurement. Default is hPa.
         * @return int32_t The measured value in the specified unit.
         */
        float getPressure(Unit unit = Unit::hPa);

        /**
         * @brief Reads the current temperature value from the sensor.
         * 
         * @return int32_t The measured temperature.
         * @note There are better sensors for temperature measurements than the MS56xx.
         */
        int32_t getTemperature();

        /**
         * @brief Provide a reference pressure value at a reference altitude in order to estimate the sealevel pressure.
         * 
         * @param pressRef The reference pressure value measured at a reference altitude.
         * @param altRef The reference altitude for the reference pressure.
         * @param unit The unit of the provided pressure value.
         */
        void setPressureReference(float pressRef, float altRef, Unit unit = Unit::hPa);

        /**
         * @brief Estimate the current altitude based on the pressure readings.
         * 
         * @return float The altitude estimate in meters.
         */
        float getAltitudeEstimate();
    private:
        /**
         * @brief Reset the sensor.
         * 
         */
        void reset();

        /**
         * @brief Read all constants from the PROM
         * 
         */
        void readPROM();

        /**
         * @brief Initialize the constants used for conversion.
         * 
         * @note This code was taken from https://github.com/RobTillaart/MS5611
         * 
         */
        void initConstants(bool mathMode = 0);

        /**
         * @brief Convert the pressure value given in Pa to a different unit.
         * 
         * @param pressure A pressure value in Pa.
         * @param unit The desired unit.
         * @return float Returns the converted value.
         */
        float convertPressure(float pressure, Unit unit);

        /**
         * @brief Small helper function for converting a uint8_t buffer to a single uint16_t.
         * 
         * @param buffer A uint8_t of size 2. More bytes will be ignored.
         * @return uint16_t A single uint16_t containing the first buffer value as MSB and the second as LSB.
         */
        uint16_t uint_8BufferTouint16_t(uint8_t* buffer);

        /**
         * @brief Function to get the delay times needed for different OSR Levels
         * 
         * @param level The oversampling rate chosen
         * @return uint32_t Returs the delay time in uS.
         */
        uint32_t osrDelay();
    private:
        /**
         * @brief Send a command to the sensor via the bus.
         * 
         * @param command The command to send.
         * @return true if successful, false otherwise.
         */
        bool busCommand(uint8_t command);

        /**
         * @brief Read data from one of the sensor's registers.
         * 
         * @param reg The register to read from.
         * @param buffer The buffer to write the received data to.
         * @param length The number of bytes to read from the register.
         * @return true if successful, false otherwise.
         */
        bool busRead(uint8_t reg, uint8_t * buffer, size_t length);
    private:
        // STA internal object for SPi abstraction
        Device * device_;
        DelayUsFunc delay_;
        OsrLevel osr_;
        Intf intf_;

        // Pressure at sealevel. Use the standard atmosphere per default.
        float sealevel_ = 1013.25;

        // The different constants; Includes Offsets, references etc.
        float C_[8];  

        // Constants for waiting
        const uint32_t RESET_DELAY = 2800; // in uS
    };
}

#endif // ifndef STA_SENSORS_MS5607_HPP