Issue with G28 command (homing)

[Nicolas Noble]

Hello,

  I'm having a weird problem with the smoothieboard and a 3D printer I just built around it - ORD Bot hadron FWIW. Basically, the G28 command for homing only works for 10mm, and then it gives up. If the endstop for that axis is reached before these 10mm, then the whole homing procedure for that axis works and the axis is homed properly. But if not, then the axis stops moving. The internal value for the position of that axis displayed by M114 shows that the homing procedure finished and is "in homing position".

  In short, it looks like that loop:

https://github.com/Smoothieware/Smoothieware/blob/edge/src/modules/tools/endstops/Endstops.cpp#L197

  in fact runs for 10mm before... stopping ? I am not sure what happens exactly there. The code looks fine to me...

  It can't even be that the endstops are being triggered, for two reasons: 1) they'd need get activated all 3 at exactly the same time, exactly after 10mm of movement, and 2) the "moving back" procedure isn't being done, as if that whole codepath was all of a sudden suspended.

  I have tried running the latest version compiled from the source, to no avail. All firmwares I've tried behave the same.

  Any idea ?

  -- Nicolas Noble

[Arthur Wolf]

Hi !

We'll figure this out. Before we go further can you tell me the result of M119 when your endstops are not triggered and when they are not triggered ?
Also post your config, it can't hurt :)

Cheers !

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[Nicolas Noble]

Sure. Here's the configuration file:

https://www.dropbox.com/s/p3id6ksdadi9r9j/config

And here's a small log. I power on the machine with all 3 axis close to their endstops, but not that close. The first G28 doesn't make the axis reach the endstops, and as I described, the homing stops after maybe 10mm on each axis. Then I issue a bunch of G28 commands until all 3 axis can reach their endstops, and position themselves properly.

pixel@seele:~$ telnet 10.12.1.230

Trying 10.12.1.230...

Connected to 10.12.1.230.

Escape character is '^]'.

Smoothie command shell

> version

Build version: edge-f03cba5, Build date: Apr 13 2014 16:48:44, MCU: LPC1768, System Clock: 100MHz

> M114

C: X:0.000 Y:0.000 Z:0.000 E: 0.0

ok

> M119

X max:1 Y max:1 Z min:1

ok

> G28

ok

> M114

C: X:-100.000 Y:-100.000 Z:265.000 E: 0.0

ok

> M119

X max:1 Y max:1 Z min:1

ok

> G28

ok

> G28

ok

> G28

ok

> G28

ok

> G28

ok

> M114

C: X:-100.000 Y:-100.000 Z:265.000 E: 0.0

ok

> M119

X max:1 Y max:1 Z min:1

ok

> quit

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[Arthur Wolf]

Yep sounds like your endstops are inverted.

Have a look here : http://smoothieware.org/3d-printer-guide#toc13 , tell us if it helps.

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[Nicolas Noble]

Okay, it makes much more sense now. What I was watching wasn't the axis trying to jog towards home. It was trying to jog out from the switch. That helps a lot, thanks! :-)

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