Hi @Daniel-Gauthier ,
Partial answers here but hopefully can git things moving. Also, I'm making assumptions here that you are OK "opening up the hood" and modifying code 😉
Consider voxl-imu-serverand the two IMUs on VOXL as not accessible via PX4/QGC. Let me reach out to a colleague who's more in this area and I'll get back to you.
We have some tools in the works for logging VOXL IMUs (and other) data easily on the VOXL side. I'll need to touch base on timeline, we are looking for a mid-end Feb release but have a developer channel that you could use if you're OK with pre-release SW (e.g. not ready for prime time...).
OK for the PX4 side I'm more versed on. The 42688p driver is here:
At least in v1.10 and v1.11, PX4 uses a single IMU as input to EKF2.
Whatever has the highest priority and is functional.... A little silly, but the two extra IMUs on there are from the v5x design spec which we were asked to try to implement, but are used as 'backups' basically.. and thus far I don't believe the backups have been used.... So it's really based on a sensor priority (which ICM42688 and ICM20648 share the same) and what sensor is started first (right now, 20602).
--> https://github.com/PX4/PX4-Autopilot/blob/master/boards/modalai/fc-v1/init/rc.board_sensors#L13
You can change the order here/comment out sensors, and it will change the default IMU being used. For validation testing, I commented out the 20602 line.
So, to make the 42688p default, make it startup first in that script.
Here's the 42688p driver for PX4:
--> https://github.com/PX4/PX4-Autopilot/tree/master/src/drivers/imu/invensense/icm42688p
Here's the 42688p driver for VOXL:
-> https://gitlab.com/voxl-public/modal-pipe-architecture/voxl-imu-server/-/blob/master/server/src/icm42688.c
Keep questions coming and we'll get to them!