MPU6000_I2C.cpp

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/**
 * @file mpu6000_i2c.cpp
 *
 * I2C interface for MPU6000 /MPU6050
 */

#include <drivers/device/i2c.h>

#include "MPU6000.hpp"

#ifdef USE_I2C

device::Device *MPU6000_I2C_interface(int bus, int device_type, bool external_bus);

class MPU6000_I2C : public device::I2C
{
public:
    MPU6000_I2C(int bus, int device_type);
    ~MPU6000_I2C() override = default;

    int read(unsigned address, void *data, unsigned count) override;
    int write(unsigned address, void *data, unsigned count) override;

protected:
    int probe() override;

private:
    int _device_type;

};


device::Device *
MPU6000_I2C_interface(int bus, int device_type, bool external_bus)
{
    return new MPU6000_I2C(bus, device_type);
}

MPU6000_I2C::MPU6000_I2C(int bus, int device_type) :
    I2C("MPU6000_I2C", nullptr, bus, PX4_I2C_MPU6050_ADDR, 400000),
    _device_type(device_type)
{
}

int
MPU6000_I2C::write(unsigned reg_speed, void *data, unsigned count)
{
    uint8_t cmd[MPU_MAX_WRITE_BUFFER_SIZE];

    if (sizeof(cmd) < (count + 1)) {
        return -EIO;
    }

    cmd[0] = MPU6000_REG(reg_speed);
    cmd[1] = *(uint8_t *)data;
    return transfer(&cmd[0], count + 1, nullptr, 0);
}

int
MPU6000_I2C::read(unsigned reg_speed, void *data, unsigned count)
{
    /* We want to avoid copying the data of MPUReport: So if the caller
     * supplies a buffer not MPUReport in size, it is assume to be a reg or
     * reg 16 read
     * Since MPUReport has a cmd at front, we must return the data
     * after that. Foe anthing else we must return it
     */
    uint32_t offset = count < sizeof(MPUReport) ? 0 : offsetof(MPUReport, status);
    uint8_t cmd = MPU6000_REG(reg_speed);
    int ret = transfer(&cmd, 1, &((uint8_t *)data)[offset], count);
    return ret == OK ? count : ret;
}

int
MPU6000_I2C::probe()
{
    uint8_t whoami = 0;
    uint8_t expected = _device_type == MPU_DEVICE_TYPE_MPU6000 ? MPU_WHOAMI_6000 : ICM_WHOAMI_20608;
    return (read(MPUREG_WHOAMI, &whoami, 1) > 0 && (whoami == expected)) ? 0 : -EIO;

}
#endif /* USE_I2C */