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Throttle Steppers not responding

My throttle steppers are responding correctly when clicking on the "TEST" button in Mobiflight but when I connect to Prosim they are not responding except for very small hunting back and fore over a distance of about an 1/8 inch.

I will just discuss #1 Throttle but I have the same issue with #2. My driver connections to Mobiflight are:

Pin 1 = PULL+

Pin 2 = DIR+

Pin 3 = PULL-

Pin 4 = DIR-

ENA+ to 5VCC

I have set the OFFSET to 53BD.0 and 1BYTE size

In Prosim I have the following:

Throttle Servo Numerical offset 53BD.0

Left Throttle Servo Output offset 53BD.0

The throttles are calibrated in Prosim and when moved manually they are working correctly.

The steppers are energized because the throttles are stiff to move manually.

As a test, I connected a 28BYJ-48 stepper driven by a ULN2003 driver and got the same result. This would make me think it is a configuration problem.

I have also tried it with throttle servo numerical set to "not installed" but in that case there is no response at all from the throttle stepper.

I have spent hours trying to work this out but now it is no longer a fun job. Can anyone help please?

Thanks,

Graeme

4 comments

4 Comments

Karl Clarke

Dec 03, 2022

Hi Greame,

You have restricted prosim to a single bit instead of a single byte.

Change the prosim value from 53BD.0 to 53BD.

That should fix the problem allowing it to use the full byte of data

gcmoir

Dec 04, 2022

Replying to

Hi Karl,

Many thanks for that guidance. Significant improvement now. The throttles are responding to inputs from Prosim but a new problem comes up. When an engine power increase or decrease is required the steppers drive the throttles hard to the stops and continue driving unless I remove power.

Throttles are calibrated correctly.

Steppers are set to 200 using the DIP switches on the drivers and Mobiflight is configured as per your instructions in Part 5 of the build guide.

Any thoughts on how to get over this one?

Thanks,

Graeme

Karl Clarke

Dec 04, 2022

Replying to

Good to hear,

Remember you need to convert the steps to servo movement. This is done by using the interpolation settings in the compare tab. After working out how many steps it takes to move the throttle from idle to flight.

Then you need to use the table to convert the servo to stepper values

0 servo = 0 steps

255 servo = 800 steps (or what value you have)

That way it can never drive past the stops

gcmoir

Dec 08, 2022

Replying to

Hi Karl,

Thanks again for the help. I haven't been able to spend much time on the sim over the last few days but yes, I can see that by changing the value in the "output value" in the interpolation settings I can control the range of movement of the throttle. I had it set at 2000 as per your build guide but that is obviously too much. I guess I need to check how many revolutions of the stepper output shaft is required to move the throttle from zero to full and then calculate the required steps from that. Should be able to get into it again this weekend.

Graeme.

Throttle Steppers not responding

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