31 #define MD_DEFAULT_I2C_ADDR 0x0f    39         MD_REG_SET_SPEED           = 0x82,
    40         MD_REG_SET_PWM_FREQ        = 0x84,
    41         MD_REG_SET_DIRECTION       = 0xaa,
    42         MD_REG_SET_MOTOR_A         = 0xa1, 
    43         MD_REG_SET_MOTOR_B         = 0xa5, 
    44         MD_REG_STEPPER_ENABLE      = 0x1a,
    45         MD_REG_STEPPER_DISABLE     = 0x1b,
    46         MD_REG_STEPPER_NUM_STEPS   = 0x1c
    51         MD_STEP_DIR_CCW    = 0x01,
    53     } MD_STEP_DIRECTION_T;