MPU6050 without repeated calibration

[jaggzh]

Must calibration be done every power-up?
Like some others, I have my board mounted sideways (it's in a button that's designed to use the rotation as the triggering).

I've set my offsets with the board mounted flat.

With the CalibrateAccel/Gyro routines run, it tunes itself and returns 0.0x rotational positions, but if I don't calibrate, the final rotation readings end up at -59, 53, 80.

The problem is, aside from the time to calibrate (which I can tolerate if necessary), the board is mounted with the Y axis somewhat up/down. I think the problem with this is that any initial offsets I set apply to when it's flat. Then when it's at an angle, if I calibrate it, it tries to PID tune all the way to assuming Z is still vertical again. (It's also trying to do that in 6 loops but, if i'm correct, it's not something I'd want it to do anyway).

Now, I can establish my initial offsets with it mounted in this position, but gravity would really be pointing mostly on Y, a bit on Z, and even a tiny bit on X possibly.

For those interested, the button fits in the left-hand's palm, and looks like this:

The MPU6050 is mounted inside the button itself (ignore the red 3d printing supports):

And here's a closeup where you can see the orientation and axes indicators I put in: