Homing help !

[MaurinElectroTextile]

I'm trayning to use the LASAURGRBL_VERSION "14.11" on my DIY laser.
The mechanical characteristics are slightly different than the Lasersaur but nothing important.
The electronic is based on the same PINs than DRIVEBOARD's pins.

Here's a little overview of what I get :
If I leave commented the #define DEBUG_IGNORE_SENSORS, nothing move.
If I uncomment it :
I can move X end Y axis with the jog

• Left switch do a X left move.
• Right switch do a X Right move.
• Top and bottom switch are OK!

If I try to do the homing cycle, all axis are going in wrong way ;-(

• My homing position is top/left

[SteveBaker]

I'm not quite sure I understand everything you're saying...but one
possibility is that the limit switches are wired in the wrong sense (ie
they are reporting "OPEN" when they are really closed - and "CLOSED" when
they're really open).

When homing, the algorithm is:

1. Move towards the top-left corner until both the X=0 and Y=0 limit
   switches are CLOSED.
2. Move away from that corner until both switches are OPEN.
3. Move about 5mm further away from the corner.
4. Stop.
5. Wherever you end up is "(0,0)" from now on.

If your switches are wired up wrong, then when the head is in the middle
of the bed, it'll think that both switches are CLOSED.

So when you home, (1) is immediately done because the switches are
seemingly closed...and we move to step (2) of the algorithm.

So it'll start moving away from the top-left until the switches are OPEN
again...but they never will be. It looks to you like the head is moving
in the wrong direction...but it's not.

This would also explain why you have to do DEBUG_IGNORE_SENSORS to make
the machine move with the jog command. Without that, it looks like the
head is hitting all of the limit switches at once, and the machine won't
move unless you are doing a HOME or have DEBUG_IGNORE_SENSORS set.

The microswitches that I used have three wires...I forget the color code -
so let's call them A, B and C. When the switch is closed, it connects A
to B, when the switch is open, it connects A to C.

I think you hooked it up to the wrong wire on the switch.

(Incidentally - it's done like that so that if a wire should break, the
machine will think it's hit a limit switch and stop moving.)

-- Steve

Maurin Donneaud wrote:

I'm trayning to use the LASAURGRBL_VERSION "14.11" on my DIY laser.
The mechanical characteristics are slightly different than the Lasersaur
but nothing important.
The electronic is based on the same PINs than DRIVEBOARD's pins.

Here's a little overview of what I get :
If I leave commented the #define DEBUG_IGNORE_SENSORS, nothing move.
If I uncomment it :
I can move X end Y axis with the jog

• Left switch do a X left move.
• Right switch do a X Right move.
• Top and bottom switch are OK!

If I try to do the homing cycle, all axis are going in wrong way ;-(

• My homing position is top/left

---

Reply to this email directly or view it on GitHub:
#57

-- Steve

[jondale]

Also a common issue is forgetting to wire up the Z limit switch. If you don't have a mechanical Z table then you can just short the wires.

[MaurinElectroTextile]

All sensors are wired in good direction ;-)
With a simple Arduino code, the digitalRead(analogPin); fonction return 0 if they are not activated (OPEN), and 1 if they are activated (CLOSE). The Z1, Z2 analogPin is grounded.

[SteveBaker]

Then the other theory...that you forgot to short out the (unused/unneeded)
Z-limit switches...seems the most likely. Because of the sense of the
signal, a disconnected switch input looks like a closed switch to the
AtMega.

-- Steve

Maurin Donneaud wrote:

All sensors are wired in good direction ;-)
With a simple Arduino code, the digitalRead(analogPin); fonction return 0
if they are not activated (OPEN), and 1 if they are activated (CLOSE).

---

Reply to this email directly or view it on GitHub:
#57 (comment)

-- Steve

[MaurinElectroTextile]

Yes, yes, the Z1, Z2 ( A4 and A5 ) are grounded.