[FEATURE REQUEST]: Add typical changes to be made to a printer firmware

[CCMCAGP]

One of the main use cases of this project is for filament that is more or less experimental/home-made, and thus varies a lot in diameter, but that you want to print anyway. This filament diameter sensor could be used to allow steady extrusion with varying diameter of filament, especially during a print.

As far as I know there's been no 'complete integration' yet. By complete integration I mean, one or several sensor that would be mounted on a classic Marlin-based printer, like a Prusa MK3S for instance. The sensors (different angles to account for ovality) would send analog readings of the filament diameter to the board, and the firmware would adjust the extrusion steps (maybe with something equivalent to M221 Set flow rate) on the fly, with a delay (i.e. taking into account the feed rate and the distance from reading to hot end).

I think this needs a number of changes to the printer's firmware, which would be useful to include in this repository too.

I find this feature very interesting myself so I'm ready to spend some time on it, but I would also appreciate the help of someone who's familiar with tweaking things in Marlin. If anyone is interested to collaborate/provide a little support to get this feature faster, please reach out! Thanks.

[drspangle]

I think this is a great idea, and an important consideration, but also potentially out of scope for this specific GitHub project. I think it would make sense to have another project as a submodule here, or potentially this project as a submodule there. It's important to maintain a separation of concerns so we don't end up having everything thrown into one box, and so that it's easier for people to contribute to projects that are going to be maintained by people that have expertise in that area. Personally, the firmware extensions would be the area that I'd be most comfortable with, but I just don't have the time to commit to that at the moment.

Let's keep an eye on this and see what we can do moving forward.

[coelholm]

@CCMCAGP, is it not covered by M405 - Filament Width Sensor On?

I remember you can talk to this sensor via I2C, so it is possible to cascade multiple sensors and have one of them reporting average between them. This change should be simple in sensor code, but it would give average between different points of filament. A new design would be required to take 3 measurements at the same point with 120 degree between them. Minimum filament diameter would be 1.443mm, if you use 2.5mm width ball bearings.