added menu item to reset BLTouch sensor alarm

[G-Forge]

On power up the BLTouch auto levelling sensor does a self test and just halts and flashes its LED if there is any obstruction on the probe pin. A common problem is if the printer is turned on and the probe is too close to the bed it goes into the alarm mode and the only way to reset it is a power on/off or send the code M280 P0 S160.

[G-Forge]

Tested OK

[Blue-Marlin]

BLTOUCH is evil!
https://www.indiegogo.com/projects/bltouch-auto-leveling-sensor-for-3d-printers#/
FAQ Nr. 7.

7. Do you have any patents?

We have several patents and some are on patent pending.

And we have already completed the patent application for this project.

That's nothing Marlin should support.

[thinkyhead]

Not the best place for this. We don't have a "probes and endstops" section, per se, but we should try to go in that general direction. So, after endstops, then servos, then probes… something like that…. But not on this line, especially as it comes immeditely after the comment describing NUM_SERVOS.

[thinkyhead]

Any changes made to this Configuration.h file must be applied to all the other Configuration.h files included with Marlin.

[thinkyhead]

It seems to me a better solution would be to automate this. If someone has one of these sensors, then before using it to home or level, the special "servo" code M280 P0 S160 should be sent. Meanwhile, the behavior should be configured so that the probe raises up far enough to be out of "alarm" range of the bed before it resets itself and tries to probe. A menu item is not easily discoverable, and it's only a workaround for the situation.

Incidentally, when the "alarm" is triggered, does the probe then show as always "triggered" or "not-triggered"?

[G-Forge]

When an alarm is triggered the the z min endstop shows as "triggered".
The alarm is triggered if there is a fault or obstruction of the probe dirt/friction or it hits during self test.
Given the issues I am happy to just close this.

[thinkyhead]

Yeah, the best approach with a sensor like this is to give it a big Z lift, make sure to use SAFE_HOMING, and perhaps we can add a new option specific to this probe so that Marlin will always send M280 P0 S160 in the deploy_probe function (at least the first one, before homing or first probe).

[Grogyan]

I have no idea how I missed this thread.

Tricky to resend a M280 P0 S160 if nozzle is too close to the bed, as you might end up with an infinite loop where clearing the error causes another error

[thinkyhead]

@Grogyan But sending 160 will also raises the pin, correct? And when the pin is raised, unless there is an ALARM state, the BLTouch should read as open, correct?

[thinkyhead]

#4839 adds a menu item to reset the BLTouch if it's in an error state.