ardupilot/libraries/AP_Baro/AP_Baro_ICM20789.h

#pragma once

#include "AP_Baro_Backend.h"

#include <AP_HAL/AP_HAL.h>
#include <AP_HAL/Semaphores.h>
#include <AP_HAL/Device.h>

#ifndef HAL_BARO_ICM20789_I2C_ADDR
// the baro is on a separate I2C address from the IMU, even though in
// the same package
#define HAL_BARO_ICM20789_I2C_ADDR 0x63
#endif

class AP_Baro_ICM20789 : public AP_Baro_Backend
{
public:
    void update() override;

    static AP_Baro_Backend *probe(AP_Baro &baro, AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev, AP_HAL::OwnPtr<AP_HAL::Device> dev_imu);
    
private:
    AP_Baro_ICM20789(AP_Baro &baro, AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev, AP_HAL::OwnPtr<AP_HAL::Device> dev_imu);

    bool init();
    bool send_cmd16(uint16_t cmd);

    bool read_calibration_data(void);

    void convert_data(uint32_t Praw, uint32_t Traw);

    void calculate_conversion_constants(const float p_Pa[3], const float p_LUT[3],
                                        float &A, float &B, float &C);
    float get_pressure(uint32_t p_LSB, uint32_t T_LSB);

    bool imu_spi_init(void);
    bool imu_i2c_init(void);
    
    void timer(void);
    
    // calibration data
    int16_t sensor_constants[4];

    uint8_t instance;

    AP_HAL::OwnPtr<AP_HAL::I2CDevice> dev;
    AP_HAL::OwnPtr<AP_HAL::Device> dev_imu;

    // time last read command was sent
    uint32_t last_measure_us;

    // accumulation structure, protected by _sem
    struct {
        float tsum;
        float psum;
        uint32_t count;
    } accum;

    // conversion constants. Thanks to invensense for including python
    // sample code in the datasheet!
    const float p_Pa_calib[3] = {45000.0, 80000.0, 105000.0};
    const float LUT_lower = 3.5 * (1U<<20);
    const float LUT_upper = 11.5 * (1U<<20);
    const float quadr_factor = 1 / 16777216.0;
    const float offst_factor = 2048.0;
};