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MarlinFirmware / Marlin

Marlin is an optimized firmware for RepRap 3D printers based on the Arduino platform. Many commercial 3D printers come with Marlin installed. Check with your vendor if you need source code for your specific machine.
https://marlinfw.org
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[FR] or [BUG] Auto-reset BLTouch #18105

Open asko58 opened 4 years ago

asko58 commented 4 years ago

Dear community,

since I've been having minor issues with my installed BLTouch (clone wired to SKR 1.3 board, TMC2209 drivers) for months I was wondering if a certain feature should not be implemented in Marlin.

Issues: Sometimes auto bed levelling at the start of a print fails with BLTouch going in to error mode (blinking). (wiring triple checked, using shielded CAT5 cable, must be electrical noise?!) Mostly the levelling data is still ok, since it levels before each print, so even if it fails once the last set of data will be pretty OK. What is a problem, however, is that the probe's pin stays down, catching on edges of the printed plastic. A manual reset of the BLTouch via LCD menu makes it reset properly and pulls the pin up again.

Possible resolution/feature request:

A Marlin feature that auto-resets the probe on error. Or is that already implemented and I didn't find it? Obviously Marlin gets the information that probing has failed but does not reset the probe.

qwewer0 commented 4 years ago

You could place an M280 P0 S90 ; Push-pin Up (Stow) after your bed leveling in the start gcode.

asko58 commented 4 years ago

Thanks for your reply. As a temporary workaround that could do the trick, but it does not take care of a possible BLTouch failure during print (that could occur). Also, I'm not sure the BLTouch recognizes the command when in an error state. I will check.

qwewer0 commented 4 years ago

Yes, it is just a temporary workaround. For the the alarm release you could use this instead: M280 P0 S160 ; Alarm Release & Push-pin UP

psavva commented 4 years ago

Have you installed a separate 5v line onto the BLTouch. I had the issue with the pin dropping years ago, and installed a separate BEC (Battery Elimination Circuit) to fix the issue...

Grogyan commented 4 years ago

The SKR1.3 has a known hardware bug, where the 5V linear regulator drops to ~4.8V

This just due to inherent excessive current drain on many parts of the circuit, The SKR1.4 fixes this by having a 2.5A 5V regulator.

MIchaeldm3 commented 4 years ago

Having a similar issue with SKR mini e3 v1.2 + bl touch v3.1

asko58 commented 4 years ago

I have already suspected something like a power drop. I have now reconfigured the hardware as follows:

I hope this helps.

But still: Wouldn't it be good if a BLTouch error could be caught in the code? Polling the probe from time to time and resetting it in case it is no longer responsive shouldn't be too hard, should it? If so, please put me wise.

sjasonsmith commented 4 years ago

@asko58, when probing fails Marlin doesn't really know why. In all likelihood a physical crash has occurred and any further action is risky. Resetting the error state could in many cases cause damage to the machine.

Is your printer actually proceeding with the print after probing fails? I thought that that would cause Marlin to die to prevent further damage.

asko58 commented 4 years ago

Is your printer actually proceeding with the print after probing fails? I thought that that would cause Marlin to die to prevent further damage.

Indeed, the printer goes on as if nothing has happened. The Z height will be incorrect but the print proceeds.

asko58 commented 4 years ago

@asko58, when probing fails Marlin doesn't really know why. In all likelihood a physical crash has occurred and any further action is risky. Resetting the error state could in many cases cause damage to the machine.

I understand your point, but I am not talking about resetting a Marlin error condition (there is none btw) but rather resetting the probe's own error state.