Getting extruder position over time

[adamwolf]

Hi!

This is awesome. Could I use this to get a list of coordinates of the extruder tip? Would I have to watch the step/dir pins per axis, or is this already calculated?

[vintagepc]

Hi there!

It's not currently exposed in a direct manner, but it should be relatively straightforward to do, with a few points of note:

The Trace system (-t on the command line) is able to capture IRQ values and dump them to a .VCD file. Many of the stepper functions (step/dir) as you note are already captured; the gotcha is this runs at a fixed sampling frequency rather than capturing every change - so if per-step accuracy is what you are looking for it may not be quite what you are looking for. (this frequency can be changed though)

If that sounds reasonable it's just a 1-line change to instruct it to also capture the position, in "steps" which you can then convert based on steps/mm and microstep resolutions. (I wouldn't necessarly recommend capturing the raw floating-point positions, as there is some hackery to mash that into a uint32 and back again for use with the integer-based IRQ system.)

Alternately, the OpenGL helper class (MK3SGL.cpp) has all of these values come to a single location since it needs to know them to draw the 3D models - so this is potentially another place where some code could be added to dump data to a file.

Yet another possible approach is the "PLY export" format. The original intent of this was to be able to capture/dump simulated prints from the 3D view for future reference - however, I would think it could easily be repurposed - if there is constant positive extrusion on the E-axis (assuming you only care about XYZ), it will continue logging positions into the polygon data to be dumped.

Can I maybe have a little more detail about what you're trying to do/the reason you'd like this data? Perhaps then I can suggest which is more suitable.

Also, what is your programming skill level? (Just so I can craft my response more accordingly).

Cheers,
~Vintage

[adamwolf]

Thanks for the response! I'm looking to run gcode and look for printhead/print collisions. I'm a decent programmer but haven't slung much C++ in a while, so depending on "how C++" this project is, I may have some more questions :)

…

On Tue, Jul 19, 2022 at 6:48 PM vintagepc ***@***.***> wrote: Hi there! It's not currently exposed in a direct manner, but it should be relatively straightforward to do, with a few points of note: The Trace system (-t on the command line) is able to capture IRQ values and dump them to a .VCD file. Many of the stepper functions (step/dir) as you note are already captured; the gotcha is this runs at a fixed sampling frequency rather than capturing every change - so if per-step accuracy is what you are looking for it may not be quite what you are looking for. (this frequency can be changed though) If that sounds reasonable it's just a 1-line change to instruct it to also capture the position, in "steps" which you can then convert based on steps/mm and microstep resolutions. (I wouldn't necessarly recommend capturing the raw floating-point positions, as there is some hackery to mash that into a uint32 and back again for use with the integer-based IRQ system.) Alternately, the OpenGL helper class (MK3SGL.cpp) has all of these values come to a single location since it needs to know them to draw the 3D models - so this is potentially another place where some code could be added to dump data to a file. Yet another possible approach is the "PLY export" format. The original intent of this was to be able to capture/dump simulated prints from the 3D view for future reference - however, I would think it could easily be repurposed - if there is constant positive extrusion on the E-axis (assuming you only care about XYZ), it will continue logging positions into the polygon data to be dumped. Can I maybe have a little more detail about what you're trying to do/the reason you'd like this data? Perhaps then I can suggest which is more suitable. Also, what is your programming skill level? (Just so I can craft my response more accordingly). Cheers, ~Vintage — Reply to this email directly, view it on GitHub <#366 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAIWYOQVFWABVUJIXXK3NTVU45F7ANCNFSM54BULAQA> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[vintagepc]

Ah, nice. That's probably on a slow enough scale that the trace system is sufficient.

This:

MK404/parts/components/TMC2130.cpp

Line 313 in edb79ce

TH.AddTrace(this, DIAG_OUT,{TC::InputPin, TC::Stepper});

is the area you'll want to be in, I think it should be as simple as adding

TH.AddTrace(this, STEP_POS_OUT, {TC::Stepper, TC::Misc});

to the end of the list.

You'll know if it worked if you see it show up in ./MK404 -t ? and if it does you should then be able to call it out by name in the --trace argument. If you need to increase the trace rate there is the --tracerate option, value is in microseconds of sim (not wall) time.

Tip: Traces don't start automatically to reduce spam. Logging is started/stopped with either the +/- keys, or using the middle-click menu TelHost->[Start/Stop]Trace

Hope that helps - and don't hesitate to ask if you need further help!