[DSC Bios & A10C] Best way to choice and make a CDU Screen (and button)

A continuous rotation servo motor will need some form of additional position feedback (such as a separate rotary encoder on the same shaft) to make a closed loop control. It makes the mechanical construction and the required software more complex compared to a stepper motor.

For applications that rotate over a limited range, a servo is easier to use, although it may be noisier and less precise than a stepper motor.

Thanks Ian. I’m glad you developed DCS-BIOS.

Stepper motor get a "reset" position (or sync) when DCS bios start?

A stepper motor receives pulses to rotate left or right by a set amount. The more pulses it gets, the more it moves before it stops. The needle doesn’t know it’s initial position, only that it was told to move. You can place a proximity switch at the 12 o’clock position so that every time the needle passes by, the switch signal tells the simulation that the needle is now at 12 o’clock. The software uses that feedback to sync and now know the exact position from that time forward. If your at 12:00 and you tell the needle to move to 3:00 and then stop it will. However, the simulation is assuming it’s at 3:00 provided that there were no mechanical drag or something stopping the needle from moving. If your at 3:00 and you tell the needle to rotate 360 degrees to come back to 3:00 again, the needle will know when it passes the 12:00 position and re-sync it’s position at that time. So with a stepper motor you need a separate digital input to read the needle when it passes by so you can report the exact location of the stepper motor’s position. The key with stepper motor is not to have mechanical friction or heavy load that will prevent it from moving it’s normal amount when told to move.

So to answer your question, yes the software usually initialized at start-up and drives the needle past the proximity switch, or to a hard stop if it’s a 270 degree motor, so that the simulation now knows the exact needle position. The next step would be to read the value of the game gauge position and then drive the motor needle to that exact location and then start tracking the game gauge from that point forward.