betaflight/src/drv_mpu3050.c

#include "board.h"

// MPU3050, Standard address 0x68
#define MPU3050_ADDRESS         0x68

// Registers
#define MPU3050_SMPLRT_DIV      0x15
#define MPU3050_DLPF_FS_SYNC    0x16
#define MPU3050_INT_CFG         0x17
#define MPU3050_TEMP_OUT        0x1B
#define MPU3050_GYRO_OUT        0x1D
#define MPU3050_USER_CTRL       0x3D
#define MPU3050_PWR_MGM         0x3E

// Bits
#define MPU3050_FS_SEL_2000DPS  0x18
#define MPU3050_DLPF_10HZ       0x05
#define MPU3050_DLPF_20HZ       0x04
#define MPU3050_DLPF_42HZ       0x03
#define MPU3050_DLPF_98HZ       0x02
#define MPU3050_DLPF_188HZ      0x01
#define MPU3050_DLPF_256HZ      0x00

#define MPU3050_USER_RESET      0x01
#define MPU3050_CLK_SEL_PLL_GX  0x01

static uint8_t mpuLowPassFilter = MPU3050_DLPF_42HZ;
static sensor_align_e gyroAlign = CW0_DEG;

static void mpu3050Init(sensor_align_e align);
static void mpu3050Read(int16_t *gyroData);
static void mpu3050ReadTemp(int16_t *tempData);

bool mpu3050Detect(sensor_t *gyro, uint16_t lpf)
{
    bool ack;

    delay(25); // datasheet page 13 says 20ms. other stuff could have been running meanwhile. but we'll be safe

    ack = i2cWrite(MPU3050_ADDRESS, MPU3050_SMPLRT_DIV, 0);
    if (!ack)
        return false;

    gyro->init = mpu3050Init;
    gyro->read = mpu3050Read;
    gyro->temperature = mpu3050ReadTemp;
    // 16.4 dps/lsb scalefactor
    gyro->scale = (((32767.0f / 16.4f) * M_PI) / ((32767.0f / 4.0f) * 180.0f * 1000000.0f));

    // default lpf is 42Hz
    switch (lpf) {
        case 256:
            mpuLowPassFilter = MPU3050_DLPF_256HZ;
            break;
        case 188:
            mpuLowPassFilter = MPU3050_DLPF_188HZ;
            break;
        case 98:
            mpuLowPassFilter = MPU3050_DLPF_98HZ;
            break;
        default:
        case 42:
            mpuLowPassFilter = MPU3050_DLPF_42HZ;
            break;
        case 20:
            mpuLowPassFilter = MPU3050_DLPF_20HZ;
            break;
        case 10:
            mpuLowPassFilter = MPU3050_DLPF_10HZ;
            break;
    }

    return true;
}

static void mpu3050Init(sensor_align_e align)
{
    bool ack;

    delay(25); // datasheet page 13 says 20ms. other stuff could have been running meanwhile. but we'll be safe

    ack = i2cWrite(MPU3050_ADDRESS, MPU3050_SMPLRT_DIV, 0);
    if (!ack)
        failureMode(3);

    i2cWrite(MPU3050_ADDRESS, MPU3050_DLPF_FS_SYNC, MPU3050_FS_SEL_2000DPS | mpuLowPassFilter);
    i2cWrite(MPU3050_ADDRESS, MPU3050_INT_CFG, 0);
    i2cWrite(MPU3050_ADDRESS, MPU3050_USER_CTRL, MPU3050_USER_RESET);
    i2cWrite(MPU3050_ADDRESS, MPU3050_PWR_MGM, MPU3050_CLK_SEL_PLL_GX);

    if (align > 0)
        gyroAlign = align;
}

// Read 3 gyro values into user-provided buffer. No overrun checking is done.
static void mpu3050Read(int16_t *gyroData)
{
    uint8_t buf[6];
    int16_t data[3];

    i2cRead(MPU3050_ADDRESS, MPU3050_GYRO_OUT, 6, buf);
    data[0] = (int16_t)((buf[0] << 8) | buf[1]) / 4;
    data[1] = (int16_t)((buf[2] << 8) | buf[3]) / 4;
    data[2] = (int16_t)((buf[4] << 8) | buf[5]) / 4;

    alignSensors(data, gyroData, gyroAlign);
}

static void mpu3050ReadTemp(int16_t *tempData)
{
    uint8_t buf[2];
    i2cRead(MPU3050_ADDRESS, MPU3050_TEMP_OUT, 2, buf);

    *tempData = 35 + ((int32_t)(buf[0] << 8 | buf[1]) + 13200) / 280;
}