Now that the initialization of MPU9250 is shared between the
AP_InertialSensor and other drivers using it as a backend, we can reset
the MPU9250 in order to put it in a known state.
Now we have the initialization code split in 2 parts:
1) Making sure the MPU9250 chip is alive and working: this is now in a
static function that may be called by other drivers that use MPU9250 as
backend.
2) The configuration of gyro and accel. Once the first part is completed
successfully the AP_InertialSensor_MPU9250 finishes the configuration of
the sensors it uses.
The only change in behavior here is that before we would try 25 time (5x
inside _hardware_init time 5x inside _init_sensor() that calls the first
function) to "boot the chip" and now we are doing "only" 5.
Add static methods to do the SPI transactions and provide the wrapper
methods when we have an instance of the object. This is useful so these
methods can be called from other contexts when the AP_InertialSensor
hasn't been initialized yet.
The Compass library is initialized before the InertialSensor. AK8963 with
MPU9250 as backend already takes care of resetting MPU9250. The problem with
also resetting it in the MPU9250 initialization code is that if the reset
happens during an internal I2C transaction, the AK8963 may hang. So here we
remove the reset inside MPU9250. There still a possibility that the first
MPU9250 initialization is not successful and it resets the chip, but it's not
happening in tests.
The previous implementation made some boards apply two rotations to suit
their default orientation. That was happening because there was an
unconditional rotation being done (commented as "rotate for bbone
default").
This commit makes that unconditional rotation as a default rotation
instead and adjusts the former additional rotations to be single
rotations.
As the datasheet says: "To prevent switching into I2C mode when using
SPI, the I2C interface should be disabled by setting the I2C_IF_DIS
configuration bit."
We also reset the sensor like PX4Firmware does for initializing the
MPU6000. See: ee1d8cd770/src/drivers/mpu6000/mpu6000.cpp (L695)
when running off a 1kHz timer and reading at 1kHz it is better to
double sample than it is to skip a sample, as skipping samples will
throw the filter off, whereas a double sample will have minimal effect
Lucas De Marchi
mirkix
Staroselskii Georgii
Gustavo Jose de Sousa
Andrew Tridgell
Jonathan Challinger
Andrew Tridgell
Víctor Mayoral Vilches
Mikhail Avkhimenia