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INDI Library v1.8.5 Released (19 Apr 2020)

April 2020 release of INDI Library v1.8.5 introduces new drivers while providing fixes and improvements to existing devices and core framework.

Always focus from one direction

2 months 2 weeks ago
ChrisRowland
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Always focus from one direction #54740
A number of focuser drivers already have backlash implemented. it isn't difficult.

Implementing it in the base class could be quite a lot more work because it would still need to refer to the actual driver to handle detecting when the initial slew has stopped, start the final slew and wait for it to stop. All of that is currently done in the driver at present.

There's also a lot of variability in how backlaash is done. I've described one that is handled in the Indi driver but it could also be in the low level driver hardware.

Better to let each driver handle it in the way that suits it.

If you need an example the Celestron SCT focuser driver has one implementation.

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2 months 2 weeks ago
knro
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Always focus from one direction #54741
I concur with Chris. This has a very good potential of introducing regressions if introduced at the base class. Let each driver handle it as it sees fit.

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2 months 2 weeks ago
kross
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Always focus from one direction #54743
Very well. That certainly makes it easier for me, since I've already done most of the work in my Waveshare driver. :)

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2 months 1 week ago
RDBeck
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Always focus from one direction #54810
I implemented backlash compensation in my moonlite-compatible arduino code at https://github.com/beckrd/Moonlite_Focuser . I always move x steps beyond the targeted amount when moving outward and then move to the target inwards. As Jasem mentioned, the focus module just waits for the moonlite driver to report that the focuser is at target position.

Feel free to use the code or logic as you see fit for your implementation.

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2 months 1 week ago
DerPit
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Always focus from one direction #54831

ChrisRowland wrote: A number of focuser drivers already have backlash implemented. it isn't difficult.


But backlash compensation is a different thing. If you use a wrong setting for BL comp, you get crap result. Both if it's too low and if it's too high.
With end-movement-inwards, you only lose some time if the value is too large.

Implementing it in the base class could be quite a lot more work because it would still need to refer to the actual driver to handle detecting when the initial slew has stopped, start the final slew and wait for it to stop. All of that is currently done in the driver at present.


I thought the base class sends a command, and then waits for the driver to report 'done'. So just send two consecutive commands if you want to move X steps out. First X+overscan, then -overscan (inwards).

There's also a lot of variability in how backlash is done. I've described one that is handled in the Indi driver but it could also be in the low level driver hardware.


IMO this would be an alternative to BL compensation, i.e., when using it, BL comp should be disabled.

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