MPU6050,dmpGetQuaternion FIFO Buffer

Using Arduino Sensors
1

Hallo Arduino-Community,

I'm working with the MPU6050 sensor data but I don't get the logic behind the dmpGetQuaternion(&q,fifoBuffer) function, which uses the fifoBuffer Bytes [0] - [15] for creating uint32_t w,x,y and z.

When looking at the underlying getFIFOBytes (uint8_t *data, uint8_t length) code:

void MPU6050::getFIFOBytes(uint8_t *data, uint8_t length) {
    if(length > 0){
        I2Cdev::readBytes(devAddr, MPU6050_RA_FIFO_R_W, length, data);
    } else {
    	*data = 0;
    }
}

knowing that: #define MPU6050_RA_FIFO_R_W 0x74
and analyzing the "readBytes(...)" function in I2Cdev.cpp I wonder where the quaternion data come from?
In the datasheet I only see 0x74 = FIFO_DATA[7:0] with no information on quaternions?

Can anybody please tell me what I missed here and where the quaternions come from?

Best regards,
Lukas

2

I am having this same problem. Did you find the answer?

3

The datasheet says what goes into the FIFO is set by the FIFO configuration register. The register descriptions are
in this document apparently: https://invensense.tdk.com/wp-content/uploads/2015/02/MPU-6000-Register-Map1.pdf