triffid/Teacup_Firmware — Issue #19: Homing with switches
Author: TinHead
Created: 2011-12-07 09:24:21+00:00
State: open

Hi guys,

It looks like there is some kind of race condition occurring when homing to the min limit switches.

I have the switches setup as recommended, tied to ground trough the NC side, with pullups enabled on the input pins non inverting. The soft limits are not enabled.

What happens is this:

- powering up
- moving the axis 10 mm
- hit home axis
- the axis moves towards the limit switch correctly
- movement stops just before hitting the limit switch - at this point Teacup considers itself at 0 (i think)
- the axis will not move unless I manually trigger the limitswitch

Now if I reset and move the switch let's say 1 mm in the positive direction it will home correctly, hitting the switch and backing up just as it is supposed to .... but this only lasts until the next reset.

So I guess what happens is that the switch is expected to be on the positive side of 0 (let's say 1) but I would expect it not to mater as long as we have a limit switch.

Is this behavior intended?