MPU9250, mag not working, gyro wrong scale

[jlecoeur]

I saw two issues with the MPU9250:

• After a few seconds, the magnetometer is not updated. Its value is either constantly [0, 0, 0] or the last read value. This prevents flying without motion tracking system, @GregoireH did you have the same issue?
• The scale of the gyroscope does not look right. When turning the drone by hand at approx 90°/s, the reading is 3.3rad/s which is around 180°/s. @jeanfrancoisburnier you checked gyroscope scales, have you noticed this before?

(branch mobrob_sparkyv2)

[jlecoeur]

edit: units

[jlecoeur]

I did some tests regarding gyro scale. I think the chip is not configured properly.

First I multiplied by 2 gyro_scale_ and obtained correct scale with gyro_range = GYRO_500_DEG;
Then I configured the module with

• gyro_range = GYRO_1000_DEG;
  -> value 2 times too high
• gyro_range = GYRO_250_DEG;
  -> value 2 times too low

[jlecoeur]

Quick fixes until we solve the issue in the driver:

• In Remove mallocs, add ChibiOS/HAL #326 there is a hack to fix the gyro scale, but it only works for the default config gyro_range = GYRO_500_DEG;.
• The magnetometer can be disabled in the attitude filter by commenting the call to update_step_mag(); in Ahrs_ekf::update() here ahrs_ekf.cpp#L425