unit_mag3110_data.hpp

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/*
 * SPDX-FileCopyrightText: 2026 M5Stack Technology CO LTD
 *
 * SPDX-License-Identifier: MIT
 */
#ifndef M5_UNIT_IMU_UNIT_UNIT_MAG3110_DATA_HPP
#define M5_UNIT_IMU_UNIT_UNIT_MAG3110_DATA_HPP
 
#include <array>
#include <cstdint>
#include <cmath>
 
namespace m5 {
namespace unit {
namespace mag3110 {
 
enum class DataRate : uint8_t {
    Rate80Hz,    
    Rate40Hz,    
    Rate20Hz,    
    Rate10Hz,    
    Rate5Hz,     
    Rate2_5Hz,   
    Rate1_25Hz,  
    Rate0_63Hz,  
};
 
enum class OverSampling : uint8_t {
    X16,   
    X32,   
    X64,   
    X128,  
};
 
// Output rate in milli-Hz at OverSampling::X16, indexed by DataRate. Milli-Hz rather than Hz so the
// oversampling division below stays exact enough at the slow end (0.63Hz / 128 is 4.9mHz)
constexpr uint32_t OUTPUT_RATE_MHZ[8] = {80000, 40000, 20000, 10000, 5000, 2500, 1250, 630};
 
constexpr uint32_t output_rate_mhz(const DataRate rate, const OverSampling os)
{
    return OUTPUT_RATE_MHZ[static_cast<uint8_t>(rate)] >> static_cast<uint8_t>(os);
}
 
constexpr uint32_t interval_ms(const DataRate rate, const OverSampling os)
{
    return (1000000U + output_rate_mhz(rate, os) - 1) / output_rate_mhz(rate, os);
}
 
constexpr uint8_t ctrl_reg1_active(const DataRate rate, const OverSampling os)
{
    return static_cast<uint8_t>((static_cast<uint8_t>(rate) << 5) | (static_cast<uint8_t>(os) << 3) | 0x01);
}
 
constexpr float RAW_UT_PER_LSB{0.10f};
constexpr float OUTPUT_LSB_PER_UT{16.0f};
 
struct Data {
    std::array<uint8_t, 7> raw{};  
 
    inline bool drdy() const
    {
        return (raw[0] & 0x08) != 0;
    }
    inline int16_t x_raw() const
    {
        return static_cast<int16_t>((raw[1] << 8) | raw[2]);
    }
    inline int16_t y_raw() const
    {
        return static_cast<int16_t>((raw[3] << 8) | raw[4]);
    }
    inline int16_t z_raw() const
    {
        return static_cast<int16_t>((raw[5] << 8) | raw[6]);
    }
 
    inline int32_t adj_x() const
    {
        return rescale(x_raw());
    }
    inline int32_t adj_y() const
    {
        return rescale(y_raw());
    }
    inline int32_t adj_z() const
    {
        return rescale(z_raw());
    }
 
private:
    static inline int32_t rescale(const int16_t raw_axis)
    {
        // Native 0.10µT/LSB -> library 16 LSB/µT: raw * 0.10 * 16
        return static_cast<int32_t>(lroundf(raw_axis * RAW_UT_PER_LSB * OUTPUT_LSB_PER_UT));
    }
};
 
}  // namespace mag3110
}  // namespace unit
}  // namespace m5
#endif