Hej everybody
Does anyone know if there is already a “good” solution for the marlin firmware to detect the filament feedrate and if the filament is empty?
I have already some ideas how to implement the sensors. But I have no idea if and how marlin can work with the sensor data.
Sailfish firmware has this, using the P-stop and a little arduio-controlled movement sensor. Perhaps that’s a good model? http://www.thingiverse.com/thing:107775 for more info.
First of all thanks 
@Laird_Popkin
Hm, never thought about sailfish as firmware. Maybe I should have a look on this piece of software.
The hardware and electronic part is not a real problem for me. But I’m far away from being a software engineer 
@Denis_Chertykov
Heard about this solution before, but couldn’t find it.
Now that I know where it is and how it works, it looks interesting. But it’s more a compensation feature than a failure detection.
But now I want both
I’ve seen the disassembled “smart extruder” from makerbot and the first thing in my head was “what, this can’t be. Makerbot brings a good idea/solution before the open source community made something?”
Ok, now I found this one :
http://forums.reprap.org/read.php?1,297350,297459#msg-297459
This is at least the detection if you are running out of filament. When I start with the software part I’ll try it.
But it would be cool to use a feedrate detection. This could include the filament detection.
The nice thing about those detectors is that they detect both when filament runs out and when there’s a tangle, and in both cases they pause the print before it’s affected, so you can fix the issue and resume printing without losing a long print. The software part is pretty simple - when a signal comes in, pause the print using the same code as the manual pause command, which (in Sailfish) has display/controls so you can set it to pause ‘cold’, then manually reload filament and resume the print. It also makes an audible alert, which you can listen for instead of having to watch the print. The detectors also use an RGB LED to display status, which is convenient.