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Brigandier
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Re: Linear Advance, is it coming back?

Feb 10, 2018 4:55 pm

koen.k wrote:
Feb 10, 2018 3:55 pm
Area51 wrote:
Feb 10, 2018 1:32 pm
Prusa should release an official firmware version with LA enabled to all of us not using USB/serial/Octoprint - we are missing out all of the other updates to filament sensor, motor stepping updates, PSU noise, etc...
The explanation in https://github.com/prusa3d/Prusa-Firmware/pull/457 implies that even with printing from SD various parts take too long to compute, using serial just makes it worse.
I'd recommend applying that PR locally and give it a try if you want LA.

I was sorely tempted to try it, but after looking through the edits that PR made I was spooked off. I don't doubt that it's good code, it's just A LOT of changes. Will let Prusa vet that out.

Got this going last night before bed. 7hr~ print with no issues other than some stringing from me getting used to this new filament.
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My MK3 Parts: [Bowden] [New Shoes] [TPU Micro Springs]

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devilhunter
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Re: Linear Advance, is it coming back?

Feb 10, 2018 11:28 pm

Area51 wrote:
Feb 10, 2018 1:32 pm

If LA is activated in the firmware, gcode M900 K0 will turn it off.
I wanted to disable Linear Advance on my MK2 for a test, and found that K0 didn't do anything compared to K15 or K30

Talked to the support chat, and they said that LA cannot be disabled with K0 in Prusa's Marlin fork.
It has to be deactivated in the firmware, like it is now.

This still true?

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Brigandier
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Re: Linear Advance, is it coming back?

Feb 20, 2018 12:51 am

XPila's latest pull request ( https://github.com/prusa3d/Prusa-Firmware/pull/475 ) has been merged into MK3 branch. This adds an "Experimental" menu with several cool things (see link). Here's the latest version of the firmware with LA enabled:
3.1.1-LA-Enabled-and-XPila.zip
My MK3 Parts: [Bowden] [New Shoes] [TPU Micro Springs]

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Brigandier
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Re: Linear Advance, is it coming back?

Feb 20, 2018 3:37 am

Just pulled this little beaut off the bed. Prusa Silver PLA, 15mm/s external perimeters with 600mm/s accel, no post cleanup yet so the feet/trunk still look rough. Posting to point out how smooth and uniform the layer lines are now compared to our previous attempts. This is with 3.1.1+LA+Recent XPila merge in firmware above. :)

Full zoom recommended. .2 layer height lookin pretty damn smooth.
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My MK3 Parts: [Bowden] [New Shoes] [TPU Micro Springs]

eric.k4
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Re: Linear Advance, is it coming back?

Feb 20, 2018 6:16 am

MK3 really should of had a 32 bit board.... sure the enisy V2 will have that.

stahlfabrik
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Re: Linear Advance, is it coming back?

Feb 20, 2018 8:37 am

I prefer a optimized software over a more power full processor

themzlab
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Re: Linear Advance, is it coming back?

Feb 20, 2018 12:11 pm

stahlfabrik wrote:
Feb 20, 2018 8:37 am
I prefer a optimized software over a more power full processor
This is kind of the same thing. A more powerful processor can allow a person to write more readable and maintainable code. I consider this to be optimal.

On the other hand, if one has a processor that is limited in performance compared to the task then you will have to 'optimize' in all kinds of places to try to save instructions (time) to make sure the tasks can be complete. One also has to work extra hard to protect code from being interrupted at the wrong time - though one can argue that is always the case no matter the power : )

The math inside the printer is at least 32 bit integer math and in some places floating point. With just an 8-bit processor a lot of instructions have to be strung together (by the compiler) to do just simple rudimentary tasks. With an upgrade to a 32 bit processor with floating point included this math would be completely trivial and this can simplify the code a great deal.

btw, I am using Linear Advance in my printer - I think I have always had it because I skipped the software versions that did not have it.

stahlfabrik
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Re: Linear Advance, is it coming back?

Feb 20, 2018 2:12 pm

You are right, of course

There is a balance to achieve.

More powerful hardware makes programmers lazy. At least there is potential for this ;-)

How is the einsy compared to Apollo flight computers? Could you land on the moon with einsy?

lol

fulcrum
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Re: Linear Advance, is it coming back?

Feb 20, 2018 5:40 pm

eric.k4 wrote:
Feb 20, 2018 6:16 am
MK3 really should of had a 32 bit board.... sure the enisy V2 will have that.
Apologies for somewhat hijacking the thread...

While I have been convinced that the MK3 will suffer from not having a 32bit processor, I believe that it will be a long time before we see a Prusa i3 with such a chip. Marlin currently does not support 32bit chips at all. I am not even sure it supports 16bit chips. That means that, first, someone would have to build a 32bit board with Marlin in mind, and then the entire Marlin firmware would have to be ported to that chip.

Since Prusa is highly invested in the Marlin firmware, I don't see them switch to another firmware that already has support for existing 32bit boards. So, basically, Prusa will either have to do the work or be at the "mercy" of other board manufacturers to do the work for them.

No matter what, the main point is that it will be more and more work with exponentially higher difficulty to squeeze more performance from the aging 8bit chips. This is made even harder by the unknown (to me) level of optimizations performed by the compiler. I don't see Prusa writing Assembly to optimize for instruction count, instruction pipelining, etc.

jonathon.b
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Re: Linear Advance, is it coming back?

Feb 20, 2018 6:35 pm

I know this is only semi related to this thread but.....

I'm pretty used to configuring Marlin so can you almost use that current version or do you have to use the files provided on Github?

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