MS5525.hpp

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#ifndef DRIVERS_MS5525_AIRSPEED_HPP_
#define DRIVERS_MS5525_AIRSPEED_HPP_

#include <drivers/airspeed/airspeed.h>
#include <math.h>
#include <mathlib/math/filter/LowPassFilter2p.hpp>
#include <px4_platform_common/getopt.h>

/* The MS5525DSO address is 111011Cx, where C is the complementary value of the pin CSB */
static constexpr uint8_t I2C_ADDRESS_1_MS5525DSO = 0x76;

static constexpr const char PATH_MS5525[] = "/dev/ms5525";

/* Measurement rate is 100Hz */
static constexpr unsigned MEAS_RATE = 100;
static constexpr float MEAS_DRIVER_FILTER_FREQ = 1.2f;
static constexpr int64_t CONVERSION_INTERVAL = (1000000 / MEAS_RATE); /* microseconds */

class MS5525 : public Airspeed
{
public:
    MS5525(uint8_t bus, uint8_t address = I2C_ADDRESS_1_MS5525DSO, const char *path = PATH_MS5525) :
        Airspeed(bus, address, CONVERSION_INTERVAL, path)
    {
    }

    ~MS5525() override = default;

private:

    /**
    * Perform a poll cycle; collect from the previous measurement
    * and start a new one.
    */
    void Run() override;

    int measure() override;
    int collect() override;

    // temperature is read once every 10 cycles
    math::LowPassFilter2p _filter{MEAS_RATE * 0.9, MEAS_DRIVER_FILTER_FREQ};

    static constexpr uint8_t CMD_RESET = 0x1E; // ADC reset command
    static constexpr uint8_t CMD_ADC_READ = 0x00; // ADC read command

    static constexpr uint8_t CMD_PROM_START = 0xA0; // Prom read command (first)

    // D1 - pressure convert commands
    // Convert D1 (OSR=256)  0x40
    // Convert D1 (OSR=512)  0x42
    // Convert D1 (OSR=1024) 0x44
    // Convert D1 (OSR=2048) 0x46
    // Convert D1 (OSR=4096) 0x48
    static constexpr uint8_t CMD_CONVERT_PRES = 0x44;

    // D2 - temperature convert commands
    // Convert D2 (OSR=256)  0x50
    // Convert D2 (OSR=512)  0x52
    // Convert D2 (OSR=1024) 0x54
    // Convert D2 (OSR=2048) 0x56
    // Convert D2 (OSR=4096) 0x58
    static constexpr uint8_t CMD_CONVERT_TEMP = 0x54;

    uint8_t _current_cmd{CMD_CONVERT_PRES};

    unsigned _pressure_count{0};

    // Qx Coefficients Matrix by Pressure Range
    //  5525DSO-pp001DS (Pmin = -1, Pmax = 1)
    static constexpr uint8_t Q1 = 15;
    static constexpr uint8_t Q2 = 17;
    static constexpr uint8_t Q3 = 7;
    static constexpr uint8_t Q4 = 5;
    static constexpr uint8_t Q5 = 7;
    static constexpr uint8_t Q6 = 21;

    // calibration coefficients from prom
    uint16_t C1{0};
    uint16_t C2{0};
    uint16_t C3{0};
    uint16_t C4{0};
    uint16_t C5{0};
    uint16_t C6{0};

    int64_t Tref{0};

    // last readings for D1 (uncompensated pressure) and D2 (uncompensated temperature)
    uint32_t D1{0};
    uint32_t D2{0};

    bool init_ms5525();
    bool _inited{false};

    uint8_t prom_crc4(uint16_t n_prom[]) const;

};

#endif /* DRIVERS_MS5525_AIRSPEED_HPP_ */